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Lindquist BE. Spreading depolarizations pose critical energy challenges in acute brain injury. J Neurochem 2024; 168:868-887. [PMID: 37787065 PMCID: PMC10987398 DOI: 10.1111/jnc.15966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 08/08/2023] [Accepted: 09/10/2023] [Indexed: 10/04/2023]
Abstract
Spreading depolarization (SD) is an electrochemical wave of neuronal depolarization mediated by extracellular K+ and glutamate, interacting with voltage-gated and ligand-gated ion channels. SD is increasingly recognized as a major cause of injury progression in stroke and brain trauma, where the mechanisms of SD-induced neuronal injury are intimately linked to energetic status and metabolic impairment. Here, I review the established working model of SD initiation and propagation. Then, I summarize the historical and recent evidence for the metabolic impact of SD, transitioning from a descriptive to a mechanistic working model of metabolic signaling and its potential to promote neuronal survival and resilience. I quantify the energetic cost of restoring ionic gradients eroded during SD, and the extent to which ion pumping impacts high-energy phosphate pools and the energy charge of affected tissue. I link energy deficits to adaptive increases in the utilization of glucose and O2, and the resulting accumulation of lactic acid and CO2 downstream of catabolic metabolic activity. Finally, I discuss the neuromodulatory and vasoactive paracrine signaling mediated by adenosine and acidosis, highlighting these metabolites' potential to protect vulnerable tissue in the context of high-frequency SD clusters.
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Affiliation(s)
- Britta E Lindquist
- Department of Neurology, University of California, San Francisco, California, USA
- Gladstone Institute of Neurological Diseases, San Francisco, California, USA
- Zuckerberg San Francisco General Hospital and Trauma Center, San Francisco, California, USA
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2
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Zhang Z, Pu Y, Yu L, Bai H, Duan W, Liu X, Nie X, Wen Z, Zheng L, Hu X, Leng X, Pan Y, Petersen NH, Liu L. Deviation From Personalized Blood Pressure Targets Correlates With Worse Outcome After Successful Recanalization. J Am Heart Assoc 2024; 13:e033633. [PMID: 38533955 PMCID: PMC11179781 DOI: 10.1161/jaha.123.033633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 02/28/2024] [Indexed: 03/28/2024]
Abstract
BACKGROUND Personalized blood pressure (BP) management for patients with acute ischemic stroke after successful endovascular thrombectomy lacks evidence. We aimed to investigate whether the deviation of BP from cerebral autoregulation limits is associated with worse outcomes. METHODS AND RESULTS We determined autoregulation by measuring mean velocity index and calculated the percentage of time and the burden (defined as the time-BP area) with BP outside the autoregulatory limits of each subject within 48 hours after endovascular thrombectomy. In total, 91 patients with large vessel occlusion stroke who had achieved successful recanalization were prospectively enrolled between May 2020 and February 2022. The burden with BP outside the autoregulatory limits was associated with poor outcome (modified Rankin Scale score 3-6) at 90 days (adjusted odds ratio, 1.28 [95% CI, 1.03-1.59]). The percentage of time with BP out of the autoregulatory limits was correlated with early neurological deterioration (National Institute of Health Stroke Scale scores increased ≥2 at 7 days) (adjusted odds ratio, 1.38 [95% CI, 1.04-1.83]). The burden of BP that decreased below the autoregulatory lower limit was associated with significant infarct growth (volume of infarct growth >11.6 mL) at 7 days (adjusted odds ratio, 1.21 [95% CI, 1.01-1.44]). The percentage of time that BP exceeded the autoregulatory upper limit was associated with symptomatic intracranial hemorrhage within 48 hours (adjusted odds ratio, 1.55 [95% CI, 1.02-2.34]). CONCLUSIONS Both the percentage of time and the burden of BP that deviates from the autoregulation-preserved range are associated with unfavorable clinical outcomes. This study highlights the potential benefits of autoregulation-guided BP management strategy after successful recanalization.
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Affiliation(s)
- Zhe Zhang
- Neurocritical Care Unit, Department of Neurology, Beijing Tiantan HospitalCapital Medical UniversityBeijingChina
- Center for Data Science, Nell Hodgson Woodruff School of NursingEmory UniversityAtlantaGA
| | - Yuehua Pu
- Neurocritical Care Unit, Department of Neurology, Beijing Tiantan HospitalCapital Medical UniversityBeijingChina
| | - Lei Yu
- Neurocritical Care Unit, Department of Neurology, Beijing Tiantan HospitalCapital Medical UniversityBeijingChina
- Department of Neurology, Beijing Anzhen HospitalCapital Medical UniversityBeijingChina
| | - Haiwei Bai
- Neurocritical Care Unit, Department of Neurology, Beijing Tiantan HospitalCapital Medical UniversityBeijingChina
- Department of NeurologyThe Forth Hospital of Hebei Medical UniversityShijiazhuangHebeiChina
| | - Wanying Duan
- Neurocritical Care Unit, Department of Neurology, Beijing Tiantan HospitalCapital Medical UniversityBeijingChina
| | - Xin Liu
- Neurocritical Care Unit, Department of Neurology, Beijing Tiantan HospitalCapital Medical UniversityBeijingChina
| | - Ximing Nie
- Neurocritical Care Unit, Department of Neurology, Beijing Tiantan HospitalCapital Medical UniversityBeijingChina
| | - Zhixuan Wen
- Neurocritical Care Unit, Department of Neurology, Beijing Tiantan HospitalCapital Medical UniversityBeijingChina
| | - Lina Zheng
- Neurocritical Care Unit, Department of Neurology, Beijing Tiantan HospitalCapital Medical UniversityBeijingChina
- Division of Neurology, Department of Medicine & TherapeuticsChinese University of Hong Kong, Prince of Wales HospitalShatinHong Kong SAR
| | - Xiao Hu
- Center for Data Science, Nell Hodgson Woodruff School of NursingEmory UniversityAtlantaGA
| | - Xinyi Leng
- Division of Neurology, Department of Medicine & TherapeuticsChinese University of Hong Kong, Prince of Wales HospitalShatinHong Kong SAR
| | - Yuesong Pan
- China National Clinical Research Center for Neurological DiseasesBeijing Tiantan HospitalBeijingChina
| | - Nils H. Petersen
- Divisions of Neurocritical Care and Stroke, Department of NeurologyYale New Haven Hospital, Yale School of MedicineNew HavenCT
| | - Liping Liu
- Neurocritical Care Unit, Department of Neurology, Beijing Tiantan HospitalCapital Medical UniversityBeijingChina
- China National Clinical Research Center for Neurological DiseasesBeijing Tiantan HospitalBeijingChina
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3
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Longden TA, Lederer WJ. Electro-metabolic signaling. J Gen Physiol 2024; 156:e202313451. [PMID: 38197953 PMCID: PMC10783436 DOI: 10.1085/jgp.202313451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 10/27/2023] [Accepted: 12/14/2023] [Indexed: 01/11/2024] Open
Abstract
Precise matching of energy substrate delivery to local metabolic needs is essential for the health and function of all tissues. Here, we outline a mechanistic framework for understanding this critical process, which we refer to as electro-metabolic signaling (EMS). All tissues exhibit changes in metabolism over varying spatiotemporal scales and have widely varying energetic needs and reserves. We propose that across tissues, common signatures of elevated metabolism or increases in energy substrate usage that exceed key local thresholds rapidly engage mechanisms that generate hyperpolarizing electrical signals in capillaries that then relax contractile elements throughout the vasculature to quickly adjust blood flow to meet changing needs. The attendant increase in energy substrate delivery serves to meet local metabolic requirements and thus avoids a mismatch in supply and demand and prevents metabolic stress. We discuss in detail key examples of EMS that our laboratories have discovered in the brain and the heart, and we outline potential further EMS mechanisms operating in tissues such as skeletal muscle, pancreas, and kidney. We suggest that the energy imbalance evoked by EMS uncoupling may be central to cellular dysfunction from which the hallmarks of aging and metabolic diseases emerge and may lead to generalized organ failure states-such as diverse flavors of heart failure and dementia. Understanding and manipulating EMS may be key to preventing or reversing these dysfunctions.
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Affiliation(s)
- Thomas A. Longden
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
- Laboratory of Neurovascular Interactions, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - W. Jonathan Lederer
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
- Laboratory of Molecular Cardiology, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA
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Jeffrey DA, Russell A, Guerrero MB, Fontaine JT, Romero P, Rosehart AC, Dabertrand F. Estrogen regulates myogenic tone in hippocampal arterioles by enhanced basal release of nitric oxide and endothelial SK Ca channel activity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.15.553442. [PMID: 37645715 PMCID: PMC10462022 DOI: 10.1101/2023.08.15.553442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Arteries and arterioles exhibit myogenic tone, a partially constricted state that allows further constriction or dilation in response to moment-to-moment fluctuations in blood pressure. The vascular endothelium that lines the internal surface of all blood vessels controls a wide variety of essential functions, including the contractility of the adjacent smooth muscle cells by providing a tonic vasodilatory influence. Studies conducted on large (pial) arteries on the surface of the brain have shown that estrogen lowers myogenic tone in female mice by enhancing nitric oxide (NO) release from the endothelium, however, whether this difference extends to the intracerebral microcirculation remains ambiguous. The existing incomplete picture of sex differences in cerebrovascular physiology combined with a deficiency in treatments that fully restore cognitive function after cerebrovascular accidents places heavy emphasis on the necessity to investigate myogenic tone regulation in the microcirculation from both male and female mice. We hypothesized that sex-linked hormone regulation of myogenic tone extends its influence on the microcirculation level, and sought to characterize it in isolated arterioles from the hippocampus, a major cognitive brain area. Using diameter measurements both in vivo (acute cranial window vascular diameter) and ex vivo (pressure myography experiments), we measured lower myogenic tone responses in hippocampal arterioles from female than male mice. By using a combined surgical and pharmacological approach, we found myogenic tone in ovariectomized (OVX) female mice matches that of males, as well as in endothelium-denuded arterioles. Interestingly, eNOS inhibition induced a larger constriction in female arterioles but only partially abolished the difference in tone. We identified that the remnant difference was mediated by a higher activity and expression of the small-conductance Ca 2+ -sensitive K + (SK) channels. Collectively, these data indicate that eNOS and SK channels exert greater vasodilatory influence over myogenic tone in female mice at physiological pressures.
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5
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Phillips B, Clark J, Martineau É, Rungta RL. Orai, RyR, and IP 3R channels cooperatively regulate calcium signaling in brain mid-capillary pericytes. Commun Biol 2023; 6:493. [PMID: 37149720 PMCID: PMC10164186 DOI: 10.1038/s42003-023-04858-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 04/21/2023] [Indexed: 05/08/2023] Open
Abstract
Pericytes are multifunctional cells of the vasculature that are vital to brain homeostasis, yet many of their fundamental physiological properties, such as Ca2+ signaling pathways, remain unexplored. We performed pharmacological and ion substitution experiments to investigate the mechanisms underlying pericyte Ca2+ signaling in acute cortical brain slices of PDGFRβ-Cre::GCaMP6f mice. We report that mid-capillary pericyte Ca2+ signalling differs from ensheathing type pericytes in that it is largely independent of L- and T-type voltage-gated calcium channels. Instead, Ca2+ signals in mid-capillary pericytes were inhibited by multiple Orai channel blockers, which also inhibited Ca2+ entry triggered by endoplasmic reticulum (ER) store depletion. An investigation into store release pathways indicated that Ca2+ transients in mid-capillary pericytes occur through a combination of IP3R and RyR activation, and that Orai store-operated calcium entry (SOCE) is required to sustain and amplify intracellular Ca2+ increases evoked by the GqGPCR agonist endothelin-1. These results suggest that Ca2+ influx via Orai channels reciprocally regulates IP3R and RyR release pathways in the ER, which together generate spontaneous Ca2+ transients and amplify Gq-coupled Ca2+ elevations in mid-capillary pericytes. Thus, SOCE is a major regulator of pericyte Ca2+ and a target for manipulating their function in health and disease.
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Affiliation(s)
- Braxton Phillips
- Department of Neuroscience, Université de Montréal, Montréal, QC, Canada
- Department of Stomatology, Faculty of Dental Medicine, Université de Montréal, Montréal, QC, H3C3J7, Canada
- Centre interdisciplinaire de recherche sur le cerveau et l'apprentissage, Université de Montréal, Montréal, QC, Canada
| | - Jenna Clark
- Department of Neuroscience, Université de Montréal, Montréal, QC, Canada
- Department of Stomatology, Faculty of Dental Medicine, Université de Montréal, Montréal, QC, H3C3J7, Canada
- Centre interdisciplinaire de recherche sur le cerveau et l'apprentissage, Université de Montréal, Montréal, QC, Canada
| | - Éric Martineau
- Department of Stomatology, Faculty of Dental Medicine, Université de Montréal, Montréal, QC, H3C3J7, Canada
- Centre interdisciplinaire de recherche sur le cerveau et l'apprentissage, Université de Montréal, Montréal, QC, Canada
| | - Ravi L Rungta
- Department of Stomatology, Faculty of Dental Medicine, Université de Montréal, Montréal, QC, H3C3J7, Canada.
- Centre interdisciplinaire de recherche sur le cerveau et l'apprentissage, Université de Montréal, Montréal, QC, Canada.
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6
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Abstract
Pericytes, attached to the surface of capillaries, play an important role in regulating local blood flow. Using optogenetic tools and genetically encoded reporters in conjunction with confocal and multiphoton imaging techniques, the 3D structure, anatomical organization, and physiology of pericytes have recently been the subject of detailed examination. This work has revealed novel functions of pericytes and morphological features such as tunneling nanotubes in brain and tunneling microtubes in heart. Here, we discuss the state of our current understanding of the roles of pericytes in blood flow control in brain and heart, where functions may differ due to the distinct spatiotemporal metabolic requirements of these tissues. We also outline the novel concept of electro-metabolic signaling, a universal mechanistic framework that links tissue metabolic state with blood flow regulation by pericytes and vascular smooth muscle cells, with capillary KATP and Kir2.1 channels as primary sensors. Finally, we present major unresolved questions and outline how they can be addressed.
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Affiliation(s)
- Thomas A Longden
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA; ,
- Laboratory of Neurovascular Interactions, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Guiling Zhao
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA; ,
- Laboratory of Molecular Cardiology, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Ashwini Hariharan
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA; ,
- Laboratory of Neurovascular Interactions, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - W Jonathan Lederer
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA; ,
- Laboratory of Molecular Cardiology, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, USA
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7
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Hariharan A, Robertson CD, Garcia DCG, Longden TA. Brain capillary pericytes are metabolic sentinels that control blood flow through a K ATP channel-dependent energy switch. Cell Rep 2022; 41:111872. [PMID: 36577387 PMCID: PMC10187957 DOI: 10.1016/j.celrep.2022.111872] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 10/10/2022] [Accepted: 11/30/2022] [Indexed: 12/28/2022] Open
Abstract
Despite the abundance of capillary thin-strand pericytes and their proximity to neurons and glia, little is known of the contributions of these cells to the control of brain hemodynamics. We demonstrate that the pharmacological activation of thin-strand pericyte KATP channels profoundly hyperpolarizes these cells, dilates upstream penetrating arterioles and arteriole-proximate capillaries, and increases capillary blood flow. Focal stimulation of pericytes with a KATP channel agonist is sufficient to evoke this response, mediated via KIR2.1 channel-dependent retrograde propagation of hyperpolarizing signals, whereas genetic inactivation of pericyte KATP channels eliminates these effects. Critically, we show that decreasing extracellular glucose to less than 1 mM or inhibiting glucose uptake by blocking GLUT1 transporters in vivo flips a mechanistic energy switch driving rapid KATP-mediated pericyte hyperpolarization to increase local blood flow. Together, our findings recast capillary pericytes as metabolic sentinels that respond to local energy deficits by increasing blood flow to neurons to prevent energetic shortfalls.
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Affiliation(s)
- Ashwini Hariharan
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD, USA; Laboratory of Neurovascular Interactions, Center for Biomedical Engineering and Technology, School of Medicine, University of Maryland, Baltimore, MD, USA
| | - Colin D Robertson
- Department of Pharmacology, School of Medicine, University of Maryland, Baltimore, MD, USA
| | - Daniela C G Garcia
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD, USA; Laboratory of Neurovascular Interactions, Center for Biomedical Engineering and Technology, School of Medicine, University of Maryland, Baltimore, MD, USA
| | - Thomas A Longden
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD, USA; Laboratory of Neurovascular Interactions, Center for Biomedical Engineering and Technology, School of Medicine, University of Maryland, Baltimore, MD, USA.
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8
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Wang S, Tang C, Liu Y, Border JJ, Roman RJ, Fan F. Impact of impaired cerebral blood flow autoregulation on cognitive impairment. FRONTIERS IN AGING 2022; 3:1077302. [PMID: 36531742 PMCID: PMC9755178 DOI: 10.3389/fragi.2022.1077302] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Accepted: 11/23/2022] [Indexed: 11/16/2023]
Abstract
Although the causes of cognitive impairment are multifactorial, emerging evidence indicates that cerebrovascular dysfunction plays an essential role in dementia. One of the most critical aspects of cerebrovascular dysfunction is autoregulation of cerebral blood flow (CBF), mainly mediated by the myogenic response, which is often impaired in dementia individuals with comorbidities, such as diabetes and hypertension. However, many unsolved questions remain. How do cerebrovascular networks coordinately modulate CBF autoregulation in health and disease? Does poor CBF autoregulation have an impact on cognitive impairment, and what are the underlying mechanisms? This review summarizes the cerebral vascular structure and myogenic (a three-phase model), metabolic (O2, CO2, adenosine, and H+), and endothelial (shear stress) factors in the regulation of CBF; and the consequences of CBF dysautoregulation. Other factors contributing to cerebrovascular dysfunction, such as impaired functional hyperemia and capillary abnormalities, are included as well. Moreover, this review highlights recent studies from our lab in terms of novel mechanisms involved in CBF autoregulation and addresses a hypothesis that there is a three-line of defense for CBF autoregulation in the cerebral vasculature.
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Affiliation(s)
- Shaoxun Wang
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, MS, United States
| | - Chengyun Tang
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, MS, United States
| | - Yedan Liu
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, MS, United States
| | - Jane J Border
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, MS, United States
| | - Richard J Roman
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, MS, United States
| | - Fan Fan
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, MS, United States
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Blackwell JA, Silva JF, Louis EM, Savu A, Largent-Milnes TM, Brooks HL, Pires PW. Cerebral arteriolar and neurovascular dysfunction after chemically induced menopause in mice. Am J Physiol Heart Circ Physiol 2022; 323:H845-H860. [PMID: 36149767 PMCID: PMC9602916 DOI: 10.1152/ajpheart.00276.2022] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 09/20/2022] [Accepted: 09/20/2022] [Indexed: 12/14/2022]
Abstract
Cognitive decline is linked to decreased cerebral blood flow, particularly in women after menopause. Impaired cerebrovascular function precedes the onset of dementia, possibly because of reduced functional dilation in parenchymal arterioles. These vessels are bottlenecks of the cerebral microcirculation, and dysfunction can limit functional hyperemia in the brain. Large-conductance Ca2+-activated K+ channels (BKCa) are the final effectors of several pathways responsible for functional hyperemia, and their expression is modulated by estrogen. However, it remains unknown whether BKCa function is altered in cerebral parenchymal arterioles after menopause. Using a chemically induced model of menopause, the 4-vinylcyclohexene diepoxide (VCD) model, which depletes follicles while maintaining intact ovaries, we hypothesized that menopause would be associated with reduced functional vasodilatory responses in cerebral parenchymal arterioles of wild-type mice via reduced BKCa function. Using pressure myography of isolated parenchymal arterioles, we observed that menopause (Meno) induced a significant increase in spontaneous myogenic tone. Endothelial function, assessed as nitric oxide production and dilation after cholinergic stimulation or endothelium-dependent hyperpolarization pathways, was unaffected by Meno. BKCa function was significantly impaired in Meno compared with control, without changes in voltage-gated K+ channel activity. Cerebral functional hyperemia, measured by laser-speckle contrast imaging during whisker stimulation, was significantly blunted in Meno mice, without detectable changes in basal perfusion. However, behavioral testing identified no change in cognition. These findings suggest that menopause induces cerebral microvascular and neurovascular deficits.NEW & NOTEWORTHY Cerebral parenchymal arterioles from menopause mice showed increased myogenic tone. We identified an impairment in smooth muscle cell BKCa channel activity, without a reduction in endothelium-dependent dilation or nitric oxide production. Microvascular dysfunction was associated with a reduction in neurovascular responses after somatosensory stimulation. Despite the neurovascular impairment, cognitive abilities were maintained in menopausal mice.
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Affiliation(s)
- Jade A Blackwell
- Department of Physiology, University of Arizona, Tucson, Arizona
| | - Josiane F Silva
- Department of Physiology, University of Arizona, Tucson, Arizona
| | - Emma M Louis
- Department of Physiology, University of Arizona, Tucson, Arizona
| | - Andrea Savu
- Department of Physiology, University of Arizona, Tucson, Arizona
| | - Tally M Largent-Milnes
- Department of Pharmacology, University of Arizona, Tucson, Arizona
- Bio5 Institute, University of Arizona, Tucson, Arizona
| | - Heddwen L Brooks
- Department of Physiology, University of Arizona, Tucson, Arizona
- Bio5 Institute, University of Arizona, Tucson, Arizona
- Sarver Heart Center, University of Arizona, Tucson, Arizona
| | - Paulo W Pires
- Department of Physiology, University of Arizona, Tucson, Arizona
- Bio5 Institute, University of Arizona, Tucson, Arizona
- Sarver Heart Center, University of Arizona, Tucson, Arizona
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10
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Jeffrey DA, Fontaine JT, Dabertrand F. Ex vivo capillary-parenchymal arteriole approach to study brain pericyte physiology. NEUROPHOTONICS 2022; 9:031919. [PMID: 36278784 PMCID: PMC9225307 DOI: 10.1117/1.nph.9.3.031919] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 06/01/2022] [Indexed: 06/16/2023]
Abstract
Significance Vascular mural cells, defined as smooth muscle cells (SMCs) and pericytes, influence brain microcirculation, but how they contribute is not fully understood. Most approaches used to investigate pericyte and capillary interactions include ex vivo retinal/slice preparations or in vivo two-photon microscopy. However, neither method adequately captures mural cell behavior without interfering neuronal tissue. Thus, there is a need to isolate vessels with their respective mural cells to study functional and pathological changes. Aim The aim of our work was to implement an ex vivo method that recapitulates vessel dynamics in the brain. Approach Expanding upon our established ex vivo capillary-parenchymal arteriole (CaPA) preparation, we isolated and pressurized arteriole-capillary branches. Using Alexa Fluor™ 633 Hydrazide, we distinguished arterioles (containing elastin) versus capillaries (lacking elastin). In addition, our transgenic SMMHC-GCaMP6f mice allowed for us to visualize mural cell morphology andCa 2 + signals. Lastly, isolated microvasculature was cultured in DMEM media (up to 72 h), mounted, and pressurized using our CaPA preparation. Results U46619 induced a decrease in capillary lumen diameter using both a bath perfusion and local application. In addition, U46619 increasedCa 2 + signaling both globally and locally in contractile pericytes. In our SMMHC-GCaMP6f mice, we saw that thin strand pericytes had sparse processes while contractile pericytes had long, thick processes that wrapped around the lumen of the capillary. Fresh and cultured pericytes constricted in response to U46619 to the same level, and upstream arteriolar dilation induced by capillary stimulation with 10 mMK + remained unchanged by culture conditions adding another application of longer treatment to our approach. Conclusion Our ex vivo CaPA methodology facilitates observation of arteriolar SMC and pericyte dynamic changes in real-time without environmental factors. This method will help to better understand how mural cells differ based on microvasculature location.
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Affiliation(s)
- Danielle A. Jeffrey
- University of Colorado Anschutz Medical Campus, Department of Anesthesiology, Aurora, Colorado, United States
| | - Jackson T. Fontaine
- University of Colorado Anschutz Medical Campus, Department of Anesthesiology, Aurora, Colorado, United States
| | - Fabrice Dabertrand
- University of Colorado Anschutz Medical Campus, Department of Anesthesiology, Aurora, Colorado, United States
- University of Colorado Anschutz Medical Campus, Department of Pharmacology, Aurora, Colorado, United States
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11
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The Effects of Acidosis on eNOS in the Systemic Vasculature: A Focus on Early Postnatal Ontogenesis. Int J Mol Sci 2022; 23:ijms23115987. [PMID: 35682667 PMCID: PMC9180972 DOI: 10.3390/ijms23115987] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 05/16/2022] [Accepted: 05/23/2022] [Indexed: 01/27/2023] Open
Abstract
The activity of many vasomotor signaling pathways strongly depends on extracellular/intracellular pH. Nitric oxide (NO) is one of the most important vasodilators produced by the endothelium. In this review, we present evidence that in most vascular beds of mature mammalian organisms metabolic or respiratory acidosis increases functional endothelial NO-synthase (eNOS) activity, despite the observation that direct effects of low pH on eNOS enzymatic activity are inhibitory. This can be explained by the fact that acidosis increases the activity of signaling pathways that positively regulate eNOS activity. The role of NO in the regulation of vascular tone is greater in early postnatal ontogenesis compared to adulthood. Importantly, in early postnatal ontogenesis acidosis also augments functional eNOS activity and its contribution to the regulation of arterial contractility. Therefore, the effect of acidosis on total peripheral resistance in neonates may be stronger than in adults and can be one of the reasons for an undesirable decrease in blood pressure during neonatal asphyxia. The latter, however, should be proven in future studies.
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12
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Gorshkova OP, Sokolova IB. Changes in the Сontribution of IKCa Сhannels to Tone Maintenanсe and Dilation of Pial Arteries in Aging Rats after Ischemia-Reperfusion. J EVOL BIOCHEM PHYS+ 2022. [DOI: 10.1134/s0022093022030152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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13
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Sancho M, Klug NR, Mughal A, Koide M, Huerta de la Cruz S, Heppner TJ, Bonev AD, Hill-Eubanks D, Nelson MT. Adenosine signaling activates ATP-sensitive K + channels in endothelial cells and pericytes in CNS capillaries. Sci Signal 2022; 15:eabl5405. [PMID: 35349300 DOI: 10.1126/scisignal.abl5405] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The dense network of capillaries composed of capillary endothelial cells (cECs) and pericytes lies in close proximity to all neurons, ideally positioning it to sense neuron- and glial-derived compounds that enhance regional and global cerebral perfusion. The membrane potential (VM) of vascular cells serves as the physiological bridge that translates brain activity into vascular function. In other beds, the ATP-sensitive K+ (KATP) channel regulates VM in vascular smooth muscle, which is absent in the capillary network. Here, with transgenic mice that expressed a dominant-negative mutant of the pore-forming Kir6.1 subunit specifically in brain cECs or pericytes, we demonstrated that KATP channels were present in both cell types and robustly controlled VM. We further showed that the signaling nucleotide adenosine acted through A2A receptors and the Gαs/cAMP/PKA pathway to activate capillary KATP channels. Moreover, KATP channel stimulation in vivo increased cerebral blood flow (CBF), an effect that was blunted by expression of the dominant-negative Kir6.1 mutant in either capillary cell type. These findings establish an important role for KATP channels in cECs and pericytes in the regulation of CBF.
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Affiliation(s)
- Maria Sancho
- Department of Pharmacology, University of Vermont, Burlington, VT 05405-0068, USA
| | - Nicholas R Klug
- Department of Pharmacology, University of Vermont, Burlington, VT 05405-0068, USA
| | - Amreen Mughal
- Department of Pharmacology, University of Vermont, Burlington, VT 05405-0068, USA
| | - Masayo Koide
- Department of Pharmacology, University of Vermont, Burlington, VT 05405-0068, USA.,Vermont Center for Cardiovascular and Brain Health, Larner College of Medicine, University of Vermont, Burlington, VT 05405-0068, USA
| | | | - Thomas J Heppner
- Department of Pharmacology, University of Vermont, Burlington, VT 05405-0068, USA
| | - Adrian D Bonev
- Department of Pharmacology, University of Vermont, Burlington, VT 05405-0068, USA
| | - David Hill-Eubanks
- Department of Pharmacology, University of Vermont, Burlington, VT 05405-0068, USA
| | - Mark T Nelson
- Department of Pharmacology, University of Vermont, Burlington, VT 05405-0068, USA.,Vermont Center for Cardiovascular and Brain Health, Larner College of Medicine, University of Vermont, Burlington, VT 05405-0068, USA.,Division of Cardiovascular Sciences, University of Manchester, Manchester M13 9PL, UK
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14
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Krishnan V, Ali S, Gonzales AL, Thakore P, Griffin CS, Yamasaki E, Alvarado MG, Johnson MT, Trebak M, Earley S. STIM1-dependent peripheral coupling governs the contractility of vascular smooth muscle cells. eLife 2022; 11:70278. [PMID: 35147077 PMCID: PMC8947769 DOI: 10.7554/elife.70278] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 02/10/2022] [Indexed: 11/28/2022] Open
Abstract
Peripheral coupling between the sarcoplasmic reticulum (SR) and plasma membrane (PM) forms signaling complexes that regulate the membrane potential and contractility of vascular smooth muscle cells (VSMCs). The mechanisms responsible for these membrane interactions are poorly understood. In many cells, STIM1 (stromal interaction molecule 1), a single-transmembrane-domain protein that resides in the endoplasmic reticulum (ER), transiently moves to ER-PM junctions in response to depletion of ER Ca2+ stores and initiates store-operated Ca2+ entry (SOCE). Fully differentiated VSMCs express STIM1 but exhibit only marginal SOCE activity. We hypothesized that STIM1 is constitutively active in contractile VSMCs and maintains peripheral coupling. In support of this concept, we found that the number and size of SR-PM interacting sites were decreased, and SR-dependent Ca2+-signaling processes were disrupted in freshly isolated cerebral artery SMCs from tamoxifen-inducible, SMC-specific STIM1-knockout (Stim1-smKO) mice. VSMCs from Stim1-smKO mice also exhibited a reduction in nanoscale colocalization between Ca2+-release sites on the SR and Ca2+-activated ion channels on the PM, accompanied by diminished channel activity. Stim1-smKO mice were hypotensive, and resistance arteries isolated from them displayed blunted contractility. These data suggest that STIM1 – independent of SR Ca2+ store depletion – is critically important for stable peripheral coupling in contractile VSMCs.
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Affiliation(s)
- Vivek Krishnan
- Department of Pharmacology, University of Nevada Reno, Reno, United States
| | - Sher Ali
- Department of Pharmacology, University of Nevada Reno, Reno, United States
| | - Albert L Gonzales
- Department of Physiology and Cell Biology, University of Nevada Reno, Reno, United States
| | - Pratish Thakore
- Department of Pharmacology, University of Nevada, Reno, Reno, United States
| | - Caoimhin S Griffin
- Department of Pharmacology, University of Nevada Reno, Reno, United States
| | - Evan Yamasaki
- Department of Pharmacology, University of Nevada Reno, Reno, United States
| | - Michael G Alvarado
- Department of Pharmacology, University of Nevada Reno, Reno, United States
| | - Martin T Johnson
- Department of Cellular and Molecular Physiology, Penn State University, Hershey, United States
| | - Mohamed Trebak
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, United States
| | - Scott Earley
- Department of Pharmacology, University of Nevada Reno, Reno, United States
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15
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De Silva TM, Sobey CG. Cerebral Vascular Biology in Health and Disease. Stroke 2022. [DOI: 10.1016/b978-0-323-69424-7.00001-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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16
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Shuvaeva VN, Gorshkova OP. Age-Related Changes in the Contribution of Nitric Oxide and Potassium Channels to Dilation of Rat Pial Arteries. J EVOL BIOCHEM PHYS+ 2021. [DOI: 10.1134/s0022093021060193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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17
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Jackson WF. Calcium-Dependent Ion Channels and the Regulation of Arteriolar Myogenic Tone. Front Physiol 2021; 12:770450. [PMID: 34819877 PMCID: PMC8607693 DOI: 10.3389/fphys.2021.770450] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 10/11/2021] [Indexed: 11/25/2022] Open
Abstract
Arterioles in the peripheral microcirculation regulate blood flow to and within tissues and organs, control capillary blood pressure and microvascular fluid exchange, govern peripheral vascular resistance, and contribute to the regulation of blood pressure. These important microvessels display pressure-dependent myogenic tone, the steady state level of contractile activity of vascular smooth muscle cells (VSMCs) that sets resting arteriolar internal diameter such that arterioles can both dilate and constrict to meet the blood flow and pressure needs of the tissues and organs that they perfuse. This perspective will focus on the Ca2+-dependent ion channels in the plasma and endoplasmic reticulum membranes of arteriolar VSMCs and endothelial cells (ECs) that regulate arteriolar tone. In VSMCs, Ca2+-dependent negative feedback regulation of myogenic tone is mediated by Ca2+-activated K+ (BKCa) channels and also Ca2+-dependent inactivation of voltage-gated Ca2+ channels (VGCC). Transient receptor potential subfamily M, member 4 channels (TRPM4); Ca2+-activated Cl− channels (CaCCs; TMEM16A/ANO1), Ca2+-dependent inhibition of voltage-gated K+ (KV) and ATP-sensitive K+ (KATP) channels; and Ca2+-induced-Ca2+ release through inositol 1,4,5-trisphosphate receptors (IP3Rs) participate in Ca2+-dependent positive-feedback regulation of myogenic tone. Calcium release from VSMC ryanodine receptors (RyRs) provide negative-feedback through Ca2+-spark-mediated control of BKCa channel activity, or positive-feedback regulation in cooperation with IP3Rs or CaCCs. In some arterioles, VSMC RyRs are silent. In ECs, transient receptor potential vanilloid subfamily, member 4 (TRPV4) channels produce Ca2+ sparklets that activate IP3Rs and intermediate and small conductance Ca2+ activated K+ (IKCa and sKCa) channels causing membrane hyperpolarization that is conducted to overlying VSMCs producing endothelium-dependent hyperpolarization and vasodilation. Endothelial IP3Rs produce Ca2+ pulsars, Ca2+ wavelets, Ca2+ waves and increased global Ca2+ levels activating EC sKCa and IKCa channels and causing Ca2+-dependent production of endothelial vasodilator autacoids such as NO, prostaglandin I2 and epoxides of arachidonic acid that mediate negative-feedback regulation of myogenic tone. Thus, Ca2+-dependent ion channels importantly contribute to many aspects of the regulation of myogenic tone in arterioles in the microcirculation.
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Affiliation(s)
- William F Jackson
- Department of Pharmacology and Toxicology, College of Osteopathic Medicine, Michigan State University, East Lansing, MI, United States
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18
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Sancho M, Kyle BD. The Large-Conductance, Calcium-Activated Potassium Channel: A Big Key Regulator of Cell Physiology. Front Physiol 2021; 12:750615. [PMID: 34744788 PMCID: PMC8567177 DOI: 10.3389/fphys.2021.750615] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 09/29/2021] [Indexed: 12/01/2022] Open
Abstract
Large-conductance Ca2+-activated K+ channels facilitate the efflux of K+ ions from a variety of cells and tissues following channel activation. It is now recognized that BK channels undergo a wide range of pre- and post-translational modifications that can dramatically alter their properties and function. This has downstream consequences in affecting cell and tissue excitability, and therefore, function. While finding the “silver bullet” in terms of clinical therapy has remained elusive, ongoing research is providing an impressive range of viable candidate proteins and mechanisms that associate with and modulate BK channel activity, respectively. Here, we provide the hallmarks of BK channel structure and function generally, and discuss important milestones in the efforts to further elucidate the diverse properties of BK channels in its many forms.
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Affiliation(s)
- Maria Sancho
- Department of Pharmacology, University of Vermont, Burlington, VT, United States
| | - Barry D Kyle
- Department of Pathology and Laboratory Medicine, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
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19
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Ion Channels, Transporters, and Sensors Interact with the Acidic Tumor Microenvironment to Modify Cancer Progression. Rev Physiol Biochem Pharmacol 2021; 182:39-84. [PMID: 34291319 DOI: 10.1007/112_2021_63] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Solid tumors, including breast carcinomas, are heterogeneous but typically characterized by elevated cellular turnover and metabolism, diffusion limitations based on the complex tumor architecture, and abnormal intra- and extracellular ion compositions particularly as regards acid-base equivalents. Carcinogenesis-related alterations in expression and function of ion channels and transporters, cellular energy levels, and organellar H+ sequestration further modify the acid-base composition within tumors and influence cancer cell functions, including cell proliferation, migration, and survival. Cancer cells defend their cytosolic pH and HCO3- concentrations better than normal cells when challenged with the marked deviations in extracellular H+, HCO3-, and lactate concentrations typical of the tumor microenvironment. Ionic gradients determine the driving forces for ion transporters and channels and influence the membrane potential. Cancer and stromal cells also sense abnormal ion concentrations via intra- and extracellular receptors that modify cancer progression and prognosis. With emphasis on breast cancer, the current review first addresses the altered ion composition and the changes in expression and functional activity of ion channels and transporters in solid cancer tissue. It then discusses how ion channels, transporters, and cellular sensors under influence of the acidic tumor microenvironment shape cancer development and progression and affect the potential of cancer therapies.
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20
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Guo P, Liu Y, Xu X, Ma G, Hou X, Fan Y, Zhang M. Coronary hypercontractility to acidosis owes to the greater activity of TMEM16A/ANO1 in the arterial smooth muscle cells. Biomed Pharmacother 2021; 139:111615. [PMID: 34243598 DOI: 10.1016/j.biopha.2021.111615] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 04/05/2021] [Accepted: 04/12/2021] [Indexed: 10/21/2022] Open
Abstract
BACKGROUND Severe acidosis deteriorates cardiac injury. Rat coronary arteries (RCAs) are unusually hypercontractive to extracellular (o) acidosis (EA). TMEM16A-encoded anoctamin 1 (ANO1), a Ca2+-activated chloride channel (CaCC), plays an important role in regulating coronary arterial tension. PURPOSE We tested the possibility that the activation of CaCCs in the arterial smooth muscle cell (ASMC) contributes to EA-induced RCA constriction. METHODS ANO1 expression was detected with immunofluorescence staining and Western blot. TMEM16A mRNA was assessed with quantitative Real-Time PCR. Cl- currents and membrane potentials were quantified with a patch clamp. The vascular tension was recorded with a myograph. Intracellular (i) level of Cl- and Ca2+ was measured with fluorescent molecular probes. RESULTS ANO1 was expressed in all tested arterial myocytes, but was much more abundant in RCA ASMCs as compared with ASMCs isolated from rat cerebral basilar, intrarenal and mesenteric arteries. EA reduced [Cl-]i levels, augmented CaCC currents exclusively in RCA ASMCs and depolarized RCA ASMCs to a greater extent. Cl- deprivation, which depleted [Cl-]i by incubating the arteries or their ASMCs in Cl--free bath solution, decreased EA-induced [Cl-]i reduction, diminished EA-induced CaCC augmentation and time-dependently depressed EA-induced RCA constriction. Inhibitor studies showed that these EA-induced effects including RCA constriction, CaCC current augmentation, [Cl-]i reduction and/or [Ca2+]i elevation were depressed by various Cl- channel blockers, [Ca2+]i release inhibitors and L-type voltage-gated Ca2+ channel inhibitor nifedipine. ANO1 antibody attenuated all observed changes induced by EA in RCA ASMCs. CONCLUSION The greater activity of RCA ASMC CaCCs complicated with an enhanced Ca2+ mobilization from both [Ca2+]i release and [Ca2+]o influx plays a pivotal role in the distinctive hypercontractility of RCAs to acidosis. Translation of these findings to human beings may lead to a new conception in our understanding and treating cardiac complications in severe acidosis.
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Affiliation(s)
- Pengmei Guo
- Department of Pharmacology, Shanxi Medical University, Xinjiannanlu 56, Taiyuan 030001, Shanxi Province, China
| | - Yu Liu
- Department of Pharmacology, Shanxi Medical University, Xinjiannanlu 56, Taiyuan 030001, Shanxi Province, China
| | - Xiaojia Xu
- Department of Pharmacology, Shanxi Medical University, Xinjiannanlu 56, Taiyuan 030001, Shanxi Province, China
| | - Guijin Ma
- Department of Pharmacology, Shanxi Medical University, Xinjiannanlu 56, Taiyuan 030001, Shanxi Province, China
| | - Xiaomin Hou
- Department of Pharmacology, Shanxi Medical University, Xinjiannanlu 56, Taiyuan 030001, Shanxi Province, China
| | - Yanying Fan
- Department of Pharmacology, Shanxi Medical University, Xinjiannanlu 56, Taiyuan 030001, Shanxi Province, China.
| | - Mingsheng Zhang
- Department of Pharmacology, Shanxi Medical University, Xinjiannanlu 56, Taiyuan 030001, Shanxi Province, China.
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21
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Zhao Y, Wang S, Song X, Yuan J, Qi D, Gu X, Yin MY, Han Z, Zhu Y, Liu Z, Zhang Y, Wei L, Wei ZZ. Glial Cell-Based Vascular Mechanisms and Transplantation Therapies in Brain Vessel and Neurodegenerative Diseases. Front Cell Neurosci 2021; 15:627682. [PMID: 33841101 PMCID: PMC8032950 DOI: 10.3389/fncel.2021.627682] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 01/26/2021] [Indexed: 12/12/2022] Open
Abstract
Neurodevelopmental and neurodegenerative diseases (NDDs) with severe neurological/psychiatric symptoms, such as cerebrovascular pathology in AD, CAA, and chronic stroke, have brought greater attention with their incidence and prevalence having markedly increased over the past few years. Causes of the significant neuropathologies, especially those observed in neurological diseases in the CNS, are commonly believed to involve multiple factors such as an age, a total environment, genetics, and an immunity contributing to their progression, neuronal, and vascular injuries. We primarily focused on the studies of glial involvement/dysfunction in part with the blood-brain barrier (BBB) and the neurovascular unit (NVU) changes, and the vascular mechanisms, which have been both suggested as critical roles in chronic stroke and many other NDDs. It has been noted that glial cells including astrocytes (which outnumber other cell types in the CNS) essentially contribute more to the BBB integrity, extracellular homeostasis, neurotransmitter release, regulation of neurogenic niches in response to neuroinflammatory stimulus, and synaptic plasticity. In a recent study for NDDs utilizing cellular and molecular biology and genetic and pharmacological tools, the role of reactive astrocytes (RACs) and gliosis was demonstrated, able to trigger pathophysiological/psychopathological detrimental changes during the disease progression. We speculate, in particular, the BBB, the NVU, and changes of the astrocytes (potentially different populations from the RACs) not only interfere with neuronal development and synaptogenesis, but also generate oxidative damages, contribute to beta-amyloid clearances and disrupted vasculature, as well as lead to neuroinflammatory disorders. During the past several decades, stem cell therapy has been investigated with a research focus to target related neuro-/vascular pathologies (cell replacement and repair) and neurological/psychiatric symptoms (paracrine protection and homeostasis). Evidence shows that transplantation of neurogenic or vasculogenic cells could be achieved to pursue differentiation and maturation within the diseased brains as expected. It would be hoped that, via regulating functions of astrocytes, astrocytic involvement, and modulation of the BBB, the NVU and astrocytes should be among major targets for therapeutics against NDDs pathogenesis by drug and cell-based therapies. The non-invasive strategies in combination with stem cell transplantation such as the well-tested intranasal deliveries for drug and stem cells by our and many other groups show great translational potentials in NDDs. Neuroimaging and clinically relevant analyzing tools need to be evaluated in various NDDs brains.
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Affiliation(s)
- Yingying Zhao
- Beijing Clinical Research Institute, Beijing, China.,Department of Anesthesiology, Emory University School of Medicine, Atlanta, GA, United States.,Department of Critical Care Medicine, Airport Hospital of Tianjin Medical University General Hospital, Tianjin, China
| | - Shuanglin Wang
- Department of Critical Care Medicine, Airport Hospital of Tianjin Medical University General Hospital, Tianjin, China.,Department of Cardiovascular Thoracic Surgery, Tianjin Medical University General Hospital, Tianjin, China.,Institute of Neurology, Tianjin Medical University General Hospital, Tianjin, China
| | - Xiaopeng Song
- Mclean Imaging Center, Harvard Medical School, McLean Hospital, Belmont, MA, United States
| | - Junliang Yuan
- Mclean Imaging Center, Harvard Medical School, McLean Hospital, Belmont, MA, United States.,Department of Neurology, Institute of Mental Health, Peking University Sixth Hospital, Beijing, China
| | - Dong Qi
- Beijing Clinical Research Institute, Beijing, China
| | - Xiaohuan Gu
- Department of Anesthesiology, Emory University School of Medicine, Atlanta, GA, United States
| | - Michael Yaoyao Yin
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT, United States.,Division of Cardiology, Emory University School of Medicine, Atlanta, GA, United States
| | - Zhou Han
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, United States
| | - Yanbing Zhu
- Beijing Clinical Research Institute, Beijing, China
| | - Zhandong Liu
- Beijing Clinical Research Institute, Beijing, China
| | - Yongbo Zhang
- Beijing Clinical Research Institute, Beijing, China
| | - Ling Wei
- Department of Anesthesiology, Emory University School of Medicine, Atlanta, GA, United States
| | - Zheng Zachory Wei
- Department of Anesthesiology, Emory University School of Medicine, Atlanta, GA, United States.,Emory Specialized Center of Sex Differences, Emory University, Atlanta, GA, United States
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22
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Role of protons in calcium signaling. Biochem J 2021; 478:895-910. [PMID: 33635336 DOI: 10.1042/bcj20200971] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/28/2021] [Accepted: 02/01/2021] [Indexed: 02/03/2023]
Abstract
Thirty-six years after the publication of the important article by Busa and Nuccitelli on the variability of intracellular pH (pHi) and the interdependence of pHi and intracellular Ca2+ concentration ([Ca2+]i), little research has been carried out on pHi and calcium signaling. Moreover, the results appear to be contradictory. Some authors claim that the increase in [Ca2+]i is due to a reduction in pHi, others that it is caused by an increase in pHi. The reasons for these conflicting results have not yet been discussed and clarified in an exhaustive manner. The idea that variations in pHi are insignificant, because cellular buffers quickly stabilize the pHi, may be a limiting and fundamentally wrong concept. In fact, it has been shown that protons can move and react in the cell before they are neutralized. Variations in pHi have a remarkable impact on [Ca2+]i and hence on some of the basic biochemical mechanisms of calcium signaling. This paper focuses on the possible triggering role of protons during their short cellular cycle and it suggests a new hypothesis for an IP3 proton dependent mechanism of action.
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23
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Extra Virgin Olive Oil Phenols Vasodilate Rat MesentericResistance Artery via Phospholipase C (PLC)-CalciumMicrodomains-Potassium Channels (BK Ca) Signals. Biomolecules 2021; 11:biom11020137. [PMID: 33494474 PMCID: PMC7912046 DOI: 10.3390/biom11020137] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/12/2021] [Accepted: 01/18/2021] [Indexed: 11/17/2022] Open
Abstract
Recent evidence suggests that the reason Extra Virgin Olive Oil (EVOO) lowers blood pressure and reduces the risk of developing hypertension is partly due to minor components of EVOO, such as phenols. However, little is still known about the mechanism(s) through which EVOO phenols mediate anti-hypertensive effects. The aim of the present study was to investigate the mechanisms of action of EVOO phenols on mesenteric resistance arteries. A pressure myograph was used to test the effect of EVOO phenols on isolated mesenteric arteries in the presence of specific inhibitors of: 1) BKca channels (Paxillin, 10-5 M); 2) L-type calcium channels (Verapamil, 10-5 M); 3) Ryanodine receptor, RyR (Ryanodine, 10-5 M); 4) inositol 1,4,5-triphosphate receptor, IP3R, (2-Aminoethyl diphenylborinate, 2-APB, 3 × 10-3 M); 5) phospholipase C, PLC, (U73122, 10-5 M), and 6) GPCR-Gαi signaling, (Pertussis Toxin, 10-5 M). EVOO phenols induced vasodilation of mesenteric arteries in a dose-dependent manner, and this effect was reduced by pre-incubation with Paxillin, Verapamil, Ryanodine, 2-APB, U73122, and Pertussis Toxin. Our data suggest that EVOO phenol-mediated vasodilation requires activation of BKca channels potentially through a local increase of subcellular calcium microdomains, a pivotal mechanism on the base of artery vasodilation. These findings provide novel mechanistic insights for understanding the vasodilatory properties of EVOO phenols on resistance arteries.
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24
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Fontaine JT, Rosehart AC, Joutel A, Dabertrand F. HB-EGF depolarizes hippocampal arterioles to restore myogenic tone in a genetic model of small vessel disease. Mech Ageing Dev 2020; 192:111389. [PMID: 33127441 PMCID: PMC7683376 DOI: 10.1016/j.mad.2020.111389] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 10/16/2020] [Accepted: 10/22/2020] [Indexed: 12/26/2022]
Abstract
Vascular cognitive impairment, the second most common cause of dementia, profoundly affects hippocampal-dependent functions. However, while the growing literature covers complex neuronal interactions, little is known about the sustaining hippocampal microcirculation. Here we examined vasoconstriction to physiological pressures of hippocampal arterioles, a fundamental feature of small arteries, in a genetic mouse model of CADASIL, an archetypal cerebral small vessel disease. Using diameter and membrane potential recordings on isolated arterioles, we observed both blunted pressure-induced vasoconstriction and smooth muscle cell depolarization in CADASIL. This impairment was abolished in the presence of voltage-gated potassium (KV1) channel blocker 4-aminopyridine, or by application of heparin-binding EGF-like growth factor (HB-EGF), which promotes KV1 channel down-regulations. Interestingly, we observed that HB-EGF induced a depolarization of the myocyte plasma membrane within the arteriolar wall in CADASIL, but not wild-type, arterioles. Collectively, our results indicate that hippocampal arterioles in CADASIL mice display a blunted contractile response to luminal pressure, similar to the defect we previously reported in cortical arterioles and pial arteries, that is rescued by HB-EGF. Hippocampal vascular dysfunction in CADASIL could then contribute to the decreased vascular reserve associated with decreased cognitive performance, and its correction may provide a therapeutic option for treating vascular cognitive impairment.
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Affiliation(s)
- Jackson T Fontaine
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Amanda C Rosehart
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Anne Joutel
- Department of Pharmacology, Larner College of Medicine University of Vermont, Burlington, VT, USA; Institute of Psychiatry and Neurosciences of Paris, INSERM UMR1266, University of Paris, GHU Paris Psychiatrie et Neurosciences, France
| | - Fabrice Dabertrand
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
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25
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Evans AM. On a Magical Mystery Tour with 8-Bromo-Cyclic ADP-Ribose: From All-or-None Block to Nanojunctions and the Cell-Wide Web. Molecules 2020; 25:E4768. [PMID: 33081414 PMCID: PMC7587525 DOI: 10.3390/molecules25204768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 09/08/2020] [Indexed: 11/16/2022] Open
Abstract
A plethora of cellular functions are controlled by calcium signals, that are greatly coordinated by calcium release from intracellular stores, the principal component of which is the sarco/endooplasmic reticulum (S/ER). In 1997 it was generally accepted that activation of various G protein-coupled receptors facilitated inositol-1,4,5-trisphosphate (IP3) production, activation of IP3 receptors and thus calcium release from S/ER. Adding to this, it was evident that S/ER resident ryanodine receptors (RyRs) could support two opposing cellular functions by delivering either highly localised calcium signals, such as calcium sparks, or by carrying propagating, global calcium waves. Coincidentally, it was reported that RyRs in mammalian cardiac myocytes might be regulated by a novel calcium mobilising messenger, cyclic adenosine diphosphate-ribose (cADPR), that had recently been discovered by HC Lee in sea urchin eggs. A reputedly selective and competitive cADPR antagonist, 8-bromo-cADPR, had been developed and was made available to us. We used 8-bromo-cADPR to further explore our observation that S/ER calcium release via RyRs could mediate two opposing functions, namely pulmonary artery dilation and constriction, in a manner seemingly independent of IP3Rs or calcium influx pathways. Importantly, the work of others had shown that, unlike skeletal and cardiac muscles, smooth muscles might express all three RyR subtypes. If this were the case in our experimental system and cADPR played a role, then 8-bromo-cADPR would surely block one of the opposing RyR-dependent functions identified, or the other, but certainly not both. The latter seemingly implausible scenario was confirmed. How could this be, do cells hold multiple, segregated SR stores that incorporate different RyR subtypes in receipt of spatially segregated signals carried by cADPR? The pharmacological profile of 8-bromo-cADPR action supported not only this, but also indicated that intracellular calcium signals were delivered across intracellular junctions formed by the S/ER. Not just one, at least two. This article retraces the steps along this journey, from the curious pharmacological profile of 8-bromo-cADPR to the discovery of the cell-wide web, a diverse network of cytoplasmic nanocourses demarcated by S/ER nanojunctions, which direct site-specific calcium flux and may thus coordinate the full panoply of cellular processes.
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Grants
- 01/A/S/07453 Biotechnology and Biological Sciences Research Council
- WT046374 , WT056423, WT070772, WT074434, WT081195AIA, WT212923, WT093147 Wellcome Trust
- PG/10/95/28657 British Heart Foundation
- FS/03/033/15432, FS/05/050, PG/05/128/19884, RG/12/14/29885, PG/10/95/28657 British Heart Foundation
- RG/12/14/29885 British Heart Foundation
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Affiliation(s)
- A Mark Evans
- Centre for Discovery Brain Sciences and Cardiovascular Science, Edinburgh Medical School, Hugh Robson Building, University of Edinburgh, Edinburgh EH8 9XD, UK
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Harraz OF, Jensen LJ. Aging, calcium channel signaling and vascular tone. Mech Ageing Dev 2020; 191:111336. [PMID: 32918949 PMCID: PMC8511598 DOI: 10.1016/j.mad.2020.111336] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 08/13/2020] [Accepted: 08/21/2020] [Indexed: 02/08/2023]
Abstract
Calcium signaling in vascular smooth muscle is crucial for arterial tone regulation and vascular function. Several proteins, including Ca2+ channels, function in an orchestrated fashion so that blood vessels can sense and respond to physiological stimuli such as changes in intravascular pressure. Activation of the voltage-dependent Ca2+ channel, Cav1.2, leads to Ca2+ influx and consequently arterial tone development and vasoconstriction. Unique among Ca2+ channels, the vascular Cav3.2 T-type channel mediates feedback inhibition of arterial tone-and therefore causes vasodilation-of resistance arteries by virtue of functional association with hyperpolarizing ion channels. During aging, several signaling modalities are altered along with vascular remodeling. There is a growing appreciation of how calcium channel signaling alters with aging and how this may affect vascular function. Here, we discuss key determinants of arterial tone development and the crucial involvement of Ca2+ channels. We next provide an updated view of key changes in Ca2+ channel expression and function during aging and how these affect vascular function. Further, this article synthesizes new questions in light of recent developments. We hope that these questions will outline a roadmap for new research, which, undoubtedly, will unravel a more comprehensive picture of arterial tone dysfunction during aging.
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Affiliation(s)
- Osama F. Harraz
- Dept. of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT, 05405 USA,Corresponding author. (O.F. Harraz)
| | - Lars Jørn Jensen
- Pathobiological Sciences, Dept. of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870 Frederiksberg C, Denmark
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Optogenetic translocation of protons out of penumbral neurons is protective in a rodent model of focal cerebral ischemia. Brain Stimul 2020; 13:881-890. [PMID: 32289721 DOI: 10.1016/j.brs.2020.03.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2019] [Revised: 03/10/2020] [Accepted: 03/11/2020] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Intracellular acidosis in the ischemic penumbra can contribute to further cell death, effectively enlarging the infarct core. Restoring the acid-base balance may enhance tissue survivability after cerebral ischemia. OBJECTIVE This study investigated whether translocating protons out of penumbral neurons could mitigate tissue acidification and induce neuroprotection in a rodent model of acute cerebral ischemia. METHODS We modulated the penumbral neurons via a light-driven pump to translocate protons out (i.e., archaerhodopsin/ArchT group) or into (i.e., channelrhodopsin-2/ChR2 group) neurons after focal cerebral ischemia in rats. Intracellular pH values were imaged via neutral red (NR) fluorescence and cerebral blood flow (CBF) was monitored through laser speckle contrast imaging (LSCI). Global CBF responses to electrical stimulation of the hindlimbs were obtained 24 h and 48 h after ischemia to assess neurological function. Behavioral and histological outcomes were evaluated 48 h after ischemia. A control group without gene modification was included. RESULTS The reduction of relative pH (RpH), the amplitude of negative peak of hypoemic response (RNP) and the hemispheric lateralization index (LI) in ArchT group were significantly less than those of the ChR2 or control group. Moreover, RpH was strongly correlated with RNP (r = 0.60) and LI (r24h = 0.80, r48h = 0.59). In addition, behavioral and histological results supported a neuroprotective effect of countering neuronal acidosis in penumbra through optogenetic stimulation. CONCLUSION(S) These results indicate that countering intracellular acidosis by optogenetically translocating protons out of penumbral neurons during the acute ischemic stage could induce protection after ischemic brain injury.
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Mori T, Cukelj R, Prévôt ME, Ustunel S, Story A, Gao Y, Diabre K, McDonough JA, Freeman EJ, Hegmann E, Clements RJ. 3D Porous Liquid Crystal Elastomer Foams Supporting Long-term Neuronal Cultures. Macromol Rapid Commun 2020; 41:e1900585. [PMID: 32009277 DOI: 10.1002/marc.201900585] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 12/18/2019] [Indexed: 02/05/2023]
Abstract
3D liquid crystal elastomer (3D-LCE) foams are used to support long-term neuronal cultures for over 60 days. Sequential imaging shows that cell density remains relatively constant throughout the culture period while the number of cells per observational area increases. In a subset of samples, retinoic acid is used to stimulate extensive neuritic outgrowth and maturation of proliferated neurons within the LCEs, inducing a threefold increase in length with cells displaying morphologies indicative of mature neurons. Designed LCEs' micro-channels have a similar diameter to endogenous parenchymal arterioles, ensuring that neurons throughout the construct have constant access to growth media during extended experiments. Here it is shown that 3D-LCEs provide a unique environment and simple method to longitudinally study spatial neuronal function, not possible in conventional culture environments, with simplistic integration into existing methodological pipelines.
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Affiliation(s)
- Taizo Mori
- Advanced Materials and Liquid Crystal Institute, 1425 Lefton Esplanade, Kent State University, Kent, Ohio, 44242-0001, USA
| | - Richard Cukelj
- Department of Biological Sciences, 1425 Lefton Esplanade, Kent State University, Kent, Ohio, 44242-0001, USA
| | - Marianne Estelle Prévôt
- Advanced Materials and Liquid Crystal Institute, 1425 Lefton Esplanade, Kent State University, Kent, Ohio, 44242-0001, USA
| | - Senay Ustunel
- Advanced Materials and Liquid Crystal Institute, 1425 Lefton Esplanade, Kent State University, Kent, Ohio, 44242-0001, USA.,Chemical Physics Interdisciplinary Program, 1425 Lefton Esplanade, Kent State University, Kent, Ohio, 44242-0001, USA
| | - Anna Story
- Department of Biological Sciences, 1425 Lefton Esplanade, Kent State University, Kent, Ohio, 44242-0001, USA
| | - Yunxiang Gao
- Advanced Materials and Liquid Crystal Institute, 1425 Lefton Esplanade, Kent State University, Kent, Ohio, 44242-0001, USA
| | - Karene Diabre
- Advanced Materials and Liquid Crystal Institute, 1425 Lefton Esplanade, Kent State University, Kent, Ohio, 44242-0001, USA
| | - Jennifer Ann McDonough
- Department of Biological Sciences, 1425 Lefton Esplanade, Kent State University, Kent, Ohio, 44242-0001, USA.,Biomedical Sciences Program, 1425 Lefton Esplanade, Kent State University, Kent, Ohio, 44242-0001, USA.,Brain Health Research Institute, 1425 Lefton Esplanade, Kent State University, Kent, Ohio, 44242-0001, USA
| | - Ernest Johnson Freeman
- Department of Biological Sciences, 1425 Lefton Esplanade, Kent State University, Kent, Ohio, 44242-0001, USA.,Biomedical Sciences Program, 1425 Lefton Esplanade, Kent State University, Kent, Ohio, 44242-0001, USA.,Brain Health Research Institute, 1425 Lefton Esplanade, Kent State University, Kent, Ohio, 44242-0001, USA
| | - Elda Hegmann
- Advanced Materials and Liquid Crystal Institute, 1425 Lefton Esplanade, Kent State University, Kent, Ohio, 44242-0001, USA.,Department of Biological Sciences, 1425 Lefton Esplanade, Kent State University, Kent, Ohio, 44242-0001, USA.,Biomedical Sciences Program, 1425 Lefton Esplanade, Kent State University, Kent, Ohio, 44242-0001, USA.,Brain Health Research Institute, 1425 Lefton Esplanade, Kent State University, Kent, Ohio, 44242-0001, USA.,Chemical Physics Interdisciplinary Program, 1425 Lefton Esplanade, Kent State University, Kent, Ohio, 44242-0001, USA
| | - Robert John Clements
- Department of Biological Sciences, 1425 Lefton Esplanade, Kent State University, Kent, Ohio, 44242-0001, USA.,Biomedical Sciences Program, 1425 Lefton Esplanade, Kent State University, Kent, Ohio, 44242-0001, USA.,Brain Health Research Institute, 1425 Lefton Esplanade, Kent State University, Kent, Ohio, 44242-0001, USA
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Yamasaki E, Thakore P, Krishnan V, Earley S. Differential expression of angiotensin II type 1 receptor subtypes within the cerebral microvasculature. Am J Physiol Heart Circ Physiol 2020; 318:H461-H469. [PMID: 31886721 PMCID: PMC7052625 DOI: 10.1152/ajpheart.00582.2019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 12/10/2019] [Accepted: 12/24/2019] [Indexed: 01/12/2023]
Abstract
Arteries and arterioles constrict in response to intraluminal pressure to generate myogenic tone, but the molecular nature of the vascular force-sensing mechanism is not fully characterized. Here, we investigated the role of angiotensin II type 1 receptors (AT1Rs) on vascular smooth muscle cells in the development of myogenic tone in cerebral parenchymal arterioles from mice. We found that pretreatment with the AT1R blocker losartan inhibited the development of myogenic tone in these vessels but did not alter the luminal diameter of arterioles with preestablished tone. Rodents express two AT1R isotypes: AT1Ra and AT1Rb. We previously demonstrated that AT1Rb is expressed at much higher levels compared with AT1Ra in cerebral pial arteries and is required for myogenic contractility in these vessels, whereas AT1Ra is unnecessary for this function. Here, we found that AT1Ra and AT1Rb are expressed at similar levels in parenchymal arterioles and that genetic knockout of AT1Ra blunted the ability of these vessels to generate myogenic tone. We also found that AT1Rb and total AT1R expression levels are much lower in parenchymal arterioles compared with pial arteries and that parenchymal arterioles are less sensitive to the vasoconstrictive effects of the endogenous AT1R ligand angiotensin II (ANG II). We conclude that 1) AT1Rs are critical for the initiation, but not the maintenance, of myogenic tone in parenchymal arterioles, and 2) lower levels of AT1Rb and total AT1R in parenchymal arterioles compared with pial arteries result in differences in myogenic and ANG II-induced vasoconstriction between these vascular segments.NEW & NOTEWORTHY Myogenic tone is critical for appropriate regulation of cerebral blood flow, but the mechanisms used by vascular smooth muscle cells to detect changes in intraluminal pressure are not fully characterized. Here, we demonstrate angiotensin II receptor type 1 (AT1R) is indispensable to initiation, but not maintenance, of myogenic tone in cerebral parenchymal arterioles. Furthermore, we demonstrate differences in AT1R expression levels lead to critical differences in contractile regulation between parenchymal arterioles and cerebral pial arteries.
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Affiliation(s)
- Evan Yamasaki
- Department of Pharmacology, Center for Molecular and Cellular Signaling in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Pratish Thakore
- Department of Pharmacology, Center for Molecular and Cellular Signaling in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Vivek Krishnan
- Department of Pharmacology, Center for Molecular and Cellular Signaling in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Scott Earley
- Department of Pharmacology, Center for Molecular and Cellular Signaling in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada
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30
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Impaired endothelium-mediated cerebrovascular reactivity promotes anxiety and respiration disorders in mice. Proc Natl Acad Sci U S A 2020; 117:1753-1761. [PMID: 31896584 DOI: 10.1073/pnas.1907467117] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Carbon dioxide (CO2), the major product of metabolism, has a strong impact on cerebral blood vessels, a phenomenon known as cerebrovascular reactivity. Several vascular risk factors such as hypertension or diabetes dampen this response, making cerebrovascular reactivity a useful diagnostic marker for incipient vascular pathology, but its functional relevance, if any, is still unclear. Here, we found that GPR4, an endothelial H+ receptor, and endothelial Gαq/11 proteins mediate the CO2/H+ effect on cerebrovascular reactivity in mice. CO2/H+ leads to constriction of vessels in the brainstem area that controls respiration. The consequential washout of CO2, if cerebrovascular reactivity is impaired, reduces respiration. In contrast, CO2 dilates vessels in other brain areas such as the amygdala. Hence, an impaired cerebrovascular reactivity amplifies the CO2 effect on anxiety. Even at atmospheric CO2 concentrations, impaired cerebrovascular reactivity caused longer apneic episodes and more anxiety, indicating that cerebrovascular reactivity is essential for normal brain function. The site-specific reactivity of vessels to CO2 is reflected by regional differences in their gene expression and the release of vasoactive factors from endothelial cells. Our data suggest the central nervous system (CNS) endothelium as a target to treat respiratory and affective disorders associated with vascular diseases.
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31
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Ion channels and the regulation of myogenic tone in peripheral arterioles. CURRENT TOPICS IN MEMBRANES 2020; 85:19-58. [DOI: 10.1016/bs.ctm.2020.01.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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32
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Rosehart AC, Johnson AC, Dabertrand F. Ex Vivo Pressurized Hippocampal Capillary-Parenchymal Arteriole Preparation for Functional Study. J Vis Exp 2019. [PMID: 31904015 DOI: 10.3791/60676] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
From subtle behavioral alterations to late-stage dementia, vascular cognitive impairment typically develops following cerebral ischemia. Stroke and cardiac arrest are remarkably sexually dimorphic diseases, and both induce cerebral ischemia. However, progress in understanding the vascular cognitive impairment, and then developing sex-specific treatments, has been partly limited by challenges in investigating the brain microcirculation from mouse models in functional studies. Here, we present an approach to examine the capillary-to-arteriole signaling in an ex vivo hippocampal capillary-parenchymal arteriole (HiCaPA) preparation from mouse brain. We describe how to isolate, cannulate, and pressurize the microcirculation to measure arteriolar diameter in response to capillary stimulation. We show which appropriate functional controls can be used to validate the HiCaPA preparation integrity and display typical results, including testing potassium as a neurovascular coupling agent and the effect of the recently characterized inhibitor of the Kir2 inward rectifying potassium channel family, ML133. Further, we compare the responses in preparations obtained from male and female mice. While these data reflect functional investigations, our approach can also be used in molecular biology, immunochemistry, and electrophysiology studies.
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Affiliation(s)
- Amanda C Rosehart
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus
| | - Abbie C Johnson
- Department of Neurological Sciences, University of Vermont Larner College of Medicine
| | - Fabrice Dabertrand
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus; Department of Pharmacology, University of Colorado Anschutz Medical Campus;
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Cardiovascular effects of prenatal stress-Are there implications for cerebrovascular, cognitive and mental health outcome? Neurosci Biobehav Rev 2019; 117:78-97. [PMID: 31708264 DOI: 10.1016/j.neubiorev.2018.05.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 05/21/2018] [Accepted: 05/22/2018] [Indexed: 01/17/2023]
Abstract
Prenatal stress programs offspring cognitive and mental health outcome. We reviewed whether prenatal stress also programs cardiovascular dysfunction which potentially modulates cerebrovascular, cognitive and mental health disorders. We focused on maternal stress and prenatal glucocorticoid (GC) exposure which have different programming effects. While maternal stress induced cortisol is mostly inactivated by the placenta, synthetic GCs freely cross the placenta and have different receptor-binding characteristics. Maternal stress, particularly anxiety, but not GC exposure, has adverse effects on maternal-fetal circulation throughout pregnancy, probably by co-activation of the maternal sympathetic nervous system, and by raising fetal catecholamines. Both effects may impair neurodevelopment. Experimental data also suggest that severe maternal stress and GC exposure during early and mid-gestation may increase the risk for cardiovascular disorders. Human data are scarce and especially lacking for older age. Programming mechanisms include aberrations in cardiac and kidney development, and functional changes in the renin-angiotensin-aldosterone-system, stress axis and peripheral and coronary vasculature. Adequate experimental or human studies examining the consequences for cerebrovascular, cognitive and mental disorders are unavailable.
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34
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Hoiland RL, Fisher JA, Ainslie PN. Regulation of the Cerebral Circulation by Arterial Carbon Dioxide. Compr Physiol 2019; 9:1101-1154. [DOI: 10.1002/cphy.c180021] [Citation(s) in RCA: 101] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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35
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Moeller AL, Hjortdal VE, Boedtkjer DMB, Boedtkjer E. Acidosis inhibits rhythmic contractions of human thoracic ducts. Physiol Rep 2019; 7:e14074. [PMID: 31025551 PMCID: PMC6483936 DOI: 10.14814/phy2.14074] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 04/04/2019] [Accepted: 04/05/2019] [Indexed: 11/24/2022] Open
Abstract
Lymph vessels counteract edema by transporting interstitial fluid from peripheral tissues to the large veins and serve as conduits for immune cells, cancer cells, and pathogens. Because edema during inflammation and malignancies is frequently associated with acidosis, we tested the hypothesis that acid-base disturbances affect human thoracic duct contractions. We studied, by isometric and isobaric myography, the contractile function of human thoracic duct segments harvested with written informed consent from patients undergoing esophageal cancer surgery. Human thoracic ducts produce complex contractile patterns consisting of tonic rises in tension (isometric myography) or decreases in diameter (isobaric myography) with superimposed phasic contractions. Active tone development decreases substantially (~90% at 30 vs. 7 mmHg) at elevated transmural pressure. Acidosis inhibits spontaneous as well as noradrenaline- and serotonin-induced phasic contractions of human thoracic ducts by 70-90% at extracellular pH 6.8 compared to 7.4 with less pronounced effects observed at pH 7.1. Mean tension responses to noradrenaline and serotonin - averaged over the entire period of agonist exposure - decrease by ~50% at extracellular pH 6.8. Elevating extracellular [K+ ] from the normal resting level around 4 mmol/L increases overall tension development but reduces phasic activity to a level that is no different between human thoracic duct segments investigated at normal and low extracellular pH. In conclusion, we show that extracellular acidosis inhibits human thoracic duct contractions with more pronounced effects on phasic than tonic contractions. We propose that reduced phasic activity of lymph vessels at low pH attenuates lymph propulsion and increases the risk of edema formation.
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Affiliation(s)
| | | | - Donna M. B. Boedtkjer
- Department of BiomedicineAarhus UniversityAarhusDenmark
- Department of Clinical MedicineAarhus UniversityAarhusDenmark
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36
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Koide M, Moshkforoush A, Tsoukias NM, Hill-Eubanks DC, Wellman GC, Nelson MT, Dabertrand F. The yin and yang of K V channels in cerebral small vessel pathologies. Microcirculation 2018; 25. [PMID: 29247493 DOI: 10.1111/micc.12436] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 12/08/2017] [Indexed: 12/14/2022]
Abstract
Cerebral SVDs encompass a group of genetic and sporadic pathological processes leading to brain lesions, cognitive decline, and stroke. There is no specific treatment for SVDs, which progress silently for years before becoming clinically symptomatic. Here, we examine parallels in the functional defects of PAs in CADASIL, a monogenic form of SVD, and in response to SAH, a common type of hemorrhagic stroke that also targets the brain microvasculature. Both animal models exhibit dysregulation of the voltage-gated potassium channel, KV 1, in arteriolar myocytes, an impairment that compromises responses to vasoactive stimuli and impacts CBF autoregulation and local dilatory responses to neuronal activity (NVC). However, the extent to which this channelopathy-like defect ultimately contributes to these pathologies is unknown. Combining experimental data with computational modeling, we describe the role of KV 1 channels in the regulation of myocyte membrane potential at rest and during the modest increase in extracellular potassium associated with NVC. We conclude that PA resting membrane potential and myogenic tone depend strongly on KV 1.2/1.5 channel density, and that reciprocal changes in KV channel density in CADASIL and SAH produce opposite effects on extracellular potassium-mediated dilation during NVC.
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Affiliation(s)
- Masayo Koide
- Department of Pharmacology, University of Vermont, Burlington, VT, USA
| | - Arash Moshkforoush
- Department of Biomedical Engineering, Florida International University, Miami, FL, USA
| | - Nikolaos M Tsoukias
- Department of Biomedical Engineering, Florida International University, Miami, FL, USA
| | | | - George C Wellman
- Department of Pharmacology, University of Vermont, Burlington, VT, USA
| | - Mark T Nelson
- Department of Pharmacology, University of Vermont, Burlington, VT, USA.,Institute of Cardiovascular Sciences, University of Manchester, Manchester, UK
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37
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Pires PW, Earley S. Neuroprotective effects of TRPA1 channels in the cerebral endothelium following ischemic stroke. eLife 2018; 7:35316. [PMID: 30239332 PMCID: PMC6177258 DOI: 10.7554/elife.35316] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 09/18/2018] [Indexed: 02/07/2023] Open
Abstract
Hypoxia and ischemia are linked to oxidative stress, which can activate the oxidant-sensitive transient receptor potential ankyrin 1 (TRPA1) channel in cerebral artery endothelial cells, leading to vasodilation. We hypothesized that TRPA1 channels in endothelial cells are activated by hypoxia-derived reactive oxygen species, leading to cerebral artery dilation and reduced ischemic damage. Using isolated cerebral arteries expressing a Ca2+ biosensor in endothelial cells, we show that 4-hydroxynonenal and hypoxia increased TRPA1 activity, detected as TRPA1 sparklets. TRPA1 activity during hypoxia was blocked by antioxidants and by TRPA1 antagonism. Hypoxia caused dilation of cerebral arteries, which was disrupted by antioxidants, TRPA1 blockade and by endothelial cell-specific Trpa1 deletion (Trpa1 ecKO mice). Loss of TRPA1 channels in endothelial cells increased cerebral infarcts, whereas TRPA1 activation with cinnamaldehyde reduced infarct in wildtype, but not Trpa1 ecKO, mice. These data suggest that endothelial TRPA1 channels are sensors of hypoxia leading to vasodilation, thereby reducing ischemic damage.
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Affiliation(s)
- Paulo Wagner Pires
- Department of Pharmacology, Center for Cardiovascular Research, University of Nevada, Reno, United States
| | - Scott Earley
- Department of Pharmacology, Center for Cardiovascular Research, University of Nevada, Reno, United States
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38
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Nanoscale remodeling of ryanodine receptor cluster size underlies cerebral microvascular dysfunction in Duchenne muscular dystrophy. Proc Natl Acad Sci U S A 2018; 115:E9745-E9752. [PMID: 30181262 PMCID: PMC6187127 DOI: 10.1073/pnas.1804593115] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is a hereditary neuromuscular disease that results from mutations in the gene encoding dystrophin. The effects of the disease on cardiac and skeletal muscle have been intensely investigated, but much less is known about how DMD impacts vascular smooth muscle cells (SMCs). Using superresolution nanoscopy, we demonstrate that clusters of ryanodine receptors (RyR2s) on the sarcoplasmic reticulum (SR) of cerebral artery SMCs from the mdx mouse model of DMD are larger compared with controls. Increased RyR2 cluster size is associated with augmented SR Ca2+ release and Ca2+-activated K+ channel activity, resulting in impaired vasoconstriction of cerebral microvessels. Our findings demonstrate that remodeling of RyR2 clusters at the molecular level results in cerebral microvascular dysfunction during DMD. Duchenne muscular dystrophy (DMD) results from mutations in the gene encoding dystrophin which lead to impaired function of skeletal and cardiac muscle, but little is known about the effects of the disease on vascular smooth muscle cells (SMCs). Here we used the mdx mouse model to study the effects of mutant dystrophin on the regulation of cerebral artery and arteriole SMC contractility, focusing on an important Ca2+-signaling pathway composed of type 2 ryanodine receptors (RyR2s) on the sarcoplasmic reticulum (SR) and large-conductance Ca2+-activated K+ (BK) channels on the plasma membrane. Nanoscale superresolution image analysis revealed that RyR2 and BKα were organized into discrete clusters, and that the mean size of RyR2 clusters that colocalized with BKα was larger in SMCs from mdx mice (∼62 RyR2 monomers) than in controls (∼40 RyR2 monomers). We further found that the frequency and signal mass of spontaneous, transient Ca2+-release events through SR RyR2s (“Ca2+ sparks”) were greater in SMCs from mdx mice. Patch-clamp electrophysiological recordings indicated a corresponding increase in Ca2+-dependent BK channel activity. Using pressure myography, we found that cerebral pial arteries and parenchymal arterioles from mdx mice failed to develop appreciable spontaneous myogenic tone. Inhibition of RyRs with tetracaine and blocking of BK channels with paxilline restored myogenic tone to control levels, demonstrating that enhanced RyR and BK channel activity is responsible for the diminished pressure-induced constriction of arteries and arterioles from mdx mice. We conclude that increased size of RyR2 protein clusters in SMCs from mdx mice increases Ca2+ spark and BK channel activity, resulting in cerebral microvascular dysfunction.
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39
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Charter ME, Lamb IR, Murrant CL. Arteriolar and capillary responses to CO2and H+in hamster skeletal muscle microvasculature: Implications for active hyperemia. Microcirculation 2018; 25:e12494. [DOI: 10.1111/micc.12494] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 06/21/2018] [Accepted: 07/18/2018] [Indexed: 12/20/2022]
Affiliation(s)
- Mackenzie E. Charter
- Department of Human Health and Nutritional Sciences; University of Guelph; Guelph Ontario Canada
| | - Iain R. Lamb
- Department of Human Health and Nutritional Sciences; University of Guelph; Guelph Ontario Canada
| | - Coral L. Murrant
- Department of Human Health and Nutritional Sciences; University of Guelph; Guelph Ontario Canada
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40
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Dopico AM, Bukiya AN, Jaggar JH. Calcium- and voltage-gated BK channels in vascular smooth muscle. Pflugers Arch 2018; 470:1271-1289. [PMID: 29748711 DOI: 10.1007/s00424-018-2151-y] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 04/27/2018] [Indexed: 02/04/2023]
Abstract
Ion channels in vascular smooth muscle regulate myogenic tone and vessel contractility. In particular, activation of calcium- and voltage-gated potassium channels of large conductance (BK channels) results in outward current that shifts the membrane potential toward more negative values, triggering a negative feed-back loop on depolarization-induced calcium influx and SM contraction. In this short review, we first present the molecular basis of vascular smooth muscle BK channels and the role of subunit composition and trafficking in the regulation of myogenic tone and vascular contractility. BK channel modulation by endogenous signaling molecules, and paracrine and endocrine mediators follows. Lastly, we describe the functional changes in smooth muscle BK channels that contribute to, or are triggered by, common physiological conditions and pathologies, including obesity, diabetes, and systemic hypertension.
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Affiliation(s)
- Alex M Dopico
- Department of Pharmacology, College of Medicine, The University of Tennessee Health Science Center, 71 South Manassas St., Memphis, TN, 38163, USA.
| | - Anna N Bukiya
- Department of Pharmacology, College of Medicine, The University of Tennessee Health Science Center, 71 South Manassas St., Memphis, TN, 38163, USA
| | - Jonathan H Jaggar
- Department of Physiology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN, USA
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Boedtkjer E. Acid-base regulation and sensing: Accelerators and brakes in metabolic regulation of cerebrovascular tone. J Cereb Blood Flow Metab 2018; 38:588-602. [PMID: 28984162 PMCID: PMC5888856 DOI: 10.1177/0271678x17733868] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 08/10/2017] [Accepted: 09/06/2017] [Indexed: 12/29/2022]
Abstract
Metabolic regulation of cerebrovascular tone directs blood flow to areas of increased neuronal activity and during disease states partially compensates for insufficient perfusion by enhancing blood flow in collateral blood vessels. Acid-base disturbances frequently occur as result of enhanced metabolism or insufficient blood supply, but despite definitive evidence that acid-base disturbances alter arterial tone, effects of individual acid-base equivalents and the underlying signaling mechanisms are still being debated. H+ is an important intra- and extracellular messenger that modifies cerebrovascular tone. In addition, low extracellular [HCO3-] promotes cerebrovascular contraction through an endothelium-dependent mechanism. CO2 alters arterial tone development via changes in intra- and extracellular pH but it is still controversial whether CO2 also has direct vasomotor effects. Vasocontractile responses to low extracellular [HCO3-] and acute CO2-induced decreases in intracellular pH can counteract H+-mediated vasorelaxation during metabolic and respiratory acidosis, respectively, and may thereby reduce the risk of capillary damage and cerebral edema that could be consequences of unopposed vasodilation. In this review, the signaling mechanisms for acid-base equivalents in cerebral arteries and the mechanisms of intracellular pH control in the arterial wall are discussed in the context of metabolic regulation of cerebrovascular tone and local perfusion.
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Affiliation(s)
- Ebbe Boedtkjer
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
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Mohanty I, Parija SC, Suklabaidya S, Rattan S. Acidosis potentiates endothelium-dependent vasorelaxation and gap junction communication in the superior mesenteric artery. Eur J Pharmacol 2018. [PMID: 29524386 DOI: 10.1016/j.ejphar.2018.03.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Extracellular pH is an important physiological determinant of vascular tone that is normally maintained within 7.35-7.45. Any change outside this range leads to severe pathological repercussions. We investigated the unknown effects of extracellular acidosis on relaxation in the superior mesenteric artery (SMA) of goat. SMA rings were employed to maintain isometric contractions at extracellular pH (pHo) 7.4 and 6.8. We analyzed the effect of acidosis (pHo 6.8) compared to physiological pH (pHo 7.4) on three signaling mediators of endothelium-dependent hyperpolarization: nitric oxide (NO), prostaglandin I2 (PGI2), and myoendothelial gap junctions (MEGJ). NO and cyclic guanosine monophosphate (cGMP) levels were compared between normal and acidic pH. Quantitative real-time PCR (qPCR) studies determined the change in expression of vascular connexin (Cx), Cx37, Cx40, and Cx43. Under acidosis, acetyl choline-induced relaxation was augmented in an endothelium-dependent manner via eNOS-NO-cGMP signaling. Conversely, at normal pH, acetyl choline-induced vasorelaxation was mediated primarily via COX-PGI2 pathway. The functional activity of MEGJ was increased under acidosis as evident from increased sensitivity of connexin blockers and upregulated gene and protein expression of connexins. In conclusion, acetyl choline-induced augmented vasorelaxation under acidosis is mediated by NOS-NO-cGMP, with a partial role of MEGJ as EDH mediators in the SMA. Present data suggest a novel role of connexin as therapeutic targets to attenuate the detrimental effect of acidosis on vascular tone.
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Affiliation(s)
- Ipsita Mohanty
- Department of Medicine, Division of Gastroenterology and Hepatology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA, United States; Department of Pharmacology and Toxicology, College of Veterinary Sciences and Animal Husbandry, Orissa University of Agriculture and Technology, Bhubaneswar 751003, Odisha, India
| | - Subas Chandra Parija
- Department of Pharmacology and Toxicology, College of Veterinary Sciences and Animal Husbandry, Orissa University of Agriculture and Technology, Bhubaneswar 751003, Odisha, India
| | - Sujit Suklabaidya
- Tumor Microenvironment and Animal Models Laboratory, Institute of Life Sciences, Bhubaneswar, Odisha, India
| | - Satish Rattan
- Department of Medicine, Division of Gastroenterology and Hepatology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA, United States.
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Rasmussen JK, Boedtkjer E. Carbonic anhydrase inhibitors modify intracellular pH transients and contractions of rat middle cerebral arteries during CO 2/HCO 3- fluctuations. J Cereb Blood Flow Metab 2018; 38:492-505. [PMID: 28318362 PMCID: PMC5851140 DOI: 10.1177/0271678x17699224] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The CO2/HCO3- buffer minimizes pH changes in response to acid-base loads, HCO3- provides substrate for Na+,HCO3--cotransporters and Cl-/HCO3--exchangers, and H+ and HCO3- modify vasomotor responses during acid-base disturbances. We show here that rat middle cerebral arteries express cytosolic, mitochondrial, extracellular, and secreted carbonic anhydrase isoforms that catalyze equilibration of the CO2/HCO3- buffer. Switching from CO2/HCO3--free to CO2/HCO3--containing extracellular solution results in initial intracellular acidification due to hydration of CO2 followed by gradual alkalinization due to cellular HCO3- uptake. Carbonic anhydrase inhibition decelerates the initial acidification and attenuates the associated transient vasoconstriction without affecting intracellular pH or artery tone at steady-state. Na+,HCO3--cotransport and Na+/H+-exchange activity after NH4+-prepulse-induced intracellular acidification are unaffected by carbonic anhydrase inhibition. Extracellular surface pH transients induced by transmembrane NH3 flux are evident under CO2/HCO3--free conditions but absent when the buffer capacity and apparent H+ mobility increase in the presence of CO2/HCO3- even after the inhibition of carbonic anhydrases. We conclude that (a) intracellular carbonic anhydrase activity accentuates pH transients and vasoconstriction in response to acute elevations of pCO2, (b) CO2/HCO3- minimizes extracellular surface pH transients without requiring carbonic anhydrase activity, and (c) carbonic anhydrases are not rate limiting for acid–base transport across cell membranes during recovery from intracellular acidification.
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Affiliation(s)
| | - Ebbe Boedtkjer
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
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Cupino TL, Watson BA, Cupino AC, Oda K, Ghamsary MG, Soriano S, Kirsch WM. Stability and bioactivity of chitosan as a transfection agent in primary human cell cultures: A case for chitosan-only controls. Carbohydr Polym 2017; 180:376-384. [PMID: 29103517 DOI: 10.1016/j.carbpol.2017.10.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 08/21/2017] [Accepted: 10/04/2017] [Indexed: 01/04/2023]
Abstract
Chitosan polymers (Cs), from which microparticles (CsM) may be precipitated to deliver various intracellular payloads, are generally considered biologically inert. We examined the impact of cell culture conditions on CsM size and the effect of chitosan on CD59 expression in primary human smooth muscle cells. We found that particle concentration and incubation time in biological buffers augmented particle size. Between pH 7.0 and pH 7.5, CsM size increased abruptly. We utilized CsM containing a plasmid with a gene for CD59 (pCsM) to transfect cells. Both CD59 mRNA and the number of CD59-positive cells were increased after pCsM treatment. Unexpectedly, CsM also augmented the number of CD59-positive cells. Cs alone enhanced CD59 expression more potently than either pCSM or CsM. This observation strongly suggests that chitosan is in fact bioactive and that chitosan-only controls should be included to avoid misattributing the activity of the delivery agent with that of the payload.
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Affiliation(s)
- Tanya L Cupino
- Neurosurgery Center for Research, Training and Education, Loma Linda University School of Medicine, Loma Linda, CA, United States; Division of Microbiology and Molecular Genetics, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA, United States.
| | - Billy A Watson
- Division of Microbiology and Molecular Genetics, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA, United States; Division of Human Anatomy, Department of Pathology and Human Anatomy, Loma Linda University School of Medicine, Loma Linda, CA, United States
| | - Alan C Cupino
- Department of Epidemiology and Biostatistics, Loma Linda University School of Public Health, Loma Linda, CA, United States
| | - Keiji Oda
- Department of Epidemiology and Biostatistics, Loma Linda University School of Public Health, Loma Linda, CA, United States
| | - Mark G Ghamsary
- Department of Epidemiology and Biostatistics, Loma Linda University School of Public Health, Loma Linda, CA, United States (Retired)
| | - Salvador Soriano
- Division of Human Anatomy, Department of Pathology and Human Anatomy, Loma Linda University School of Medicine, Loma Linda, CA, United States
| | - Wolff M Kirsch
- Neurosurgery Center for Research, Training and Education, Loma Linda University School of Medicine, Loma Linda, CA, United States.
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Aleksandrowicz M, Dworakowska B, Dolowy K, Kozniewska E. Restoration of the response of the middle cerebral artery of the rat to acidosis in hyposmotic hyponatremia by the opener of large-conductance calcium sensitive potassium channels (BK Ca). J Cereb Blood Flow Metab 2017; 37:3219-3230. [PMID: 28058990 PMCID: PMC5584697 DOI: 10.1177/0271678x16685575] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Hyposmotic hyponatremia (the decrease of extracellular concentration of sodium ions from 145 to 121 mM and the decrease of hyposmolality from 300 to 250 mOsm/kg H2O) impairs response of the middle cerebral artery (MCA) to acetylcholine and NO donor (S-nitroso-N-acetyl-DL-penicillamine). Since acidosis activates a similar intracellular signaling pathway, the present study was designed to verify the hypothesis that the response of the MCA to acidosis is impaired during acute hyposmotic hyponatremia due to abnormal NO-related signal transduction in vascular smooth muscle cells. Studies performed on isolated, cannulated, and pressurized rat MCA revealed that hyposmotic hyponatremia impaired the response of the MCA to acidosis and this was associated with hyposmolality rather than with decreased sodium ion concentration. Response to acidosis was restored by the BKCa but not by the KATP channel activator. Patch-clamp electrophysiology performed on myocytes freshly isolated from MCAs, demonstrated that hyposmotic hyponatremia does not affect BKCa currents but decreases the voltage-dependency of the activation of the BKCa channels in the presence of a specific opener of these channels. Our study suggests that reduced sensitivity of BKCa channels in the MCA to agonists results in the lack of response of this artery to acidosis during acute hyposmotic hyponatremia.
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Affiliation(s)
- Marta Aleksandrowicz
- 1 Department of Neurosurgery, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
| | - Beata Dworakowska
- 2 Department of Biophysics, Warsaw University of Life Sciences, Warsaw, Poland
| | - Krzysztof Dolowy
- 2 Department of Biophysics, Warsaw University of Life Sciences, Warsaw, Poland
| | - Ewa Kozniewska
- 1 Department of Neurosurgery, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland.,3 Department of Experimental and Clinical Physiology, Medical University of Warsaw, Warsaw, Poland
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Spray S, Johansson SE, Radziwon-Balicka A, Haanes KA, Warfvinge K, Povlsen GK, Kelly PAT, Edvinsson L. Enhanced contractility of intraparenchymal arterioles after global cerebral ischaemia in rat - new insights into the development of delayed cerebral hypoperfusion. Acta Physiol (Oxf) 2017; 220:417-431. [PMID: 27864916 DOI: 10.1111/apha.12834] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 08/11/2016] [Accepted: 11/15/2016] [Indexed: 12/13/2022]
Abstract
AIM Delayed cerebral hypoperfusion is a secondary complication found in the days after transient global cerebral ischaemia that worsens the ischaemic damage inflicted by the initial transient episode of global cerebral ischaemia. A recent study demonstrated increased cerebral vasoconstriction in the large arteries on the brain surface (pial arteries) after global cerebral ischaemia. However, smaller arterioles inside the brain (parenchymal arterioles) are equally important in the regulation of cerebral blood flow and yet their pathophysiology after global cerebral ischaemia is largely unknown. Therefore, we investigated whether increased contractility occurs in the intraparenchymal arterioles. METHODS Global cerebral ischaemia was induced in male Wistar rats by bilateral common carotid occlusion for 15 min combined with hypovolaemia. Regional cerebral blood flow was determined by quantitative autoradiography. Intraparenchymal arterioles were isolated and pressurized, and concentration-response curves to endothelin-1 with and without the endothelin B receptor-selective antagonist BQ788 was generated. Endothelin B receptor expression was investigated by quantitative flow cytometry and immunohistochemistry. RESULTS We observed increased endothelin-1-mediated contractility of parenchymal arterioles correlating with reduced cerebral blood flow of the cortex, hippocampus and caudate nucleus 48 h after global cerebral ischaemia. The increased endothelin-1-mediated contractility was abolished by BQ788, and the vascular smooth muscle cell-specific expression of endothelin B receptors was significantly increased after global cerebral ischaemia. CONCLUSION Increased endothelin-1-mediated contractility and expression of endothelin B receptors in the intraparenchymal vasculature contributes to the development of delayed cerebral hypoperfusion after global cerebral ischaemia in combination with vascular changes of the pial vasculature.
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Affiliation(s)
- S. Spray
- Department of Clinical Experimental Research; Glostrup Research Institute; Rigshospitalet; Glostrup Denmark
| | - S. E. Johansson
- Department of Clinical Experimental Research; Glostrup Research Institute; Rigshospitalet; Glostrup Denmark
| | - A. Radziwon-Balicka
- Department of Clinical Experimental Research; Glostrup Research Institute; Rigshospitalet; Glostrup Denmark
| | - K. A. Haanes
- Department of Clinical Experimental Research; Glostrup Research Institute; Rigshospitalet; Glostrup Denmark
| | - K. Warfvinge
- Department of Clinical Experimental Research; Glostrup Research Institute; Rigshospitalet; Glostrup Denmark
- Division of Experimental Vascular Research; Department of Clinical Sciences; Lund University Hospital; Lund Sweden
| | - G. K. Povlsen
- Department of Clinical Experimental Research; Glostrup Research Institute; Rigshospitalet; Glostrup Denmark
| | - P. A. T. Kelly
- Centre for Cognitive and Neural System; University of Edinburgh; Edinburgh UK
| | - L. Edvinsson
- Department of Clinical Experimental Research; Glostrup Research Institute; Rigshospitalet; Glostrup Denmark
- Division of Experimental Vascular Research; Department of Clinical Sciences; Lund University Hospital; Lund Sweden
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Capillary K +-sensing initiates retrograde hyperpolarization to increase local cerebral blood flow. Nat Neurosci 2017; 20:717-726. [PMID: 28319610 PMCID: PMC5404963 DOI: 10.1038/nn.4533] [Citation(s) in RCA: 326] [Impact Index Per Article: 46.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 02/19/2017] [Indexed: 12/21/2022]
Abstract
Blood flow into the brain is dynamically regulated to satisfy the changing metabolic requirements of neurons, but how this is accomplished has remained unclear. Here, we demonstrate a central role for capillary endothelial cells in sensing neural activity and communicating it to upstream arterioles in the form of an electrical vasodilatory signal. We further demonstrate that this signal is initiated by extracellular potassium (K+)—a byproduct of neural activity—which activates capillary endothelial cell inward-rectifier K+ (KIR2.1) channels to produce a rapidly propagating retrograde hyperpolarization that causes upstream arteriolar dilation, increasing blood flow into the capillary bed. Our results establish brain capillaries as an active sensory web that converts changes in external K+ into rapid, ‘inside-out’ electrical signaling to direct blood flow to active brain regions.
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48
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Tykocki NR, Boerman EM, Jackson WF. Smooth Muscle Ion Channels and Regulation of Vascular Tone in Resistance Arteries and Arterioles. Compr Physiol 2017; 7:485-581. [PMID: 28333380 DOI: 10.1002/cphy.c160011] [Citation(s) in RCA: 212] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Vascular tone of resistance arteries and arterioles determines peripheral vascular resistance, contributing to the regulation of blood pressure and blood flow to, and within the body's tissues and organs. Ion channels in the plasma membrane and endoplasmic reticulum of vascular smooth muscle cells (SMCs) in these blood vessels importantly contribute to the regulation of intracellular Ca2+ concentration, the primary determinant of SMC contractile activity and vascular tone. Ion channels provide the main source of activator Ca2+ that determines vascular tone, and strongly contribute to setting and regulating membrane potential, which, in turn, regulates the open-state-probability of voltage gated Ca2+ channels (VGCCs), the primary source of Ca2+ in resistance artery and arteriolar SMCs. Ion channel function is also modulated by vasoconstrictors and vasodilators, contributing to all aspects of the regulation of vascular tone. This review will focus on the physiology of VGCCs, voltage-gated K+ (KV) channels, large-conductance Ca2+-activated K+ (BKCa) channels, strong-inward-rectifier K+ (KIR) channels, ATP-sensitive K+ (KATP) channels, ryanodine receptors (RyRs), inositol 1,4,5-trisphosphate receptors (IP3Rs), and a variety of transient receptor potential (TRP) channels that contribute to pressure-induced myogenic tone in resistance arteries and arterioles, the modulation of the function of these ion channels by vasoconstrictors and vasodilators, their role in the functional regulation of tissue blood flow and their dysfunction in diseases such as hypertension, obesity, and diabetes. © 2017 American Physiological Society. Compr Physiol 7:485-581, 2017.
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Affiliation(s)
- Nathan R Tykocki
- Department of Pharmacology, University of Vermont, Burlington, Vermont, USA
| | - Erika M Boerman
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri, USA
| | - William F Jackson
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan, USA
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Latorre R, Castillo K, Carrasquel-Ursulaez W, Sepulveda RV, Gonzalez-Nilo F, Gonzalez C, Alvarez O. Molecular Determinants of BK Channel Functional Diversity and Functioning. Physiol Rev 2017; 97:39-87. [DOI: 10.1152/physrev.00001.2016] [Citation(s) in RCA: 151] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Large-conductance Ca2+- and voltage-activated K+ (BK) channels play many physiological roles ranging from the maintenance of smooth muscle tone to hearing and neurosecretion. BK channels are tetramers in which the pore-forming α subunit is coded by a single gene ( Slowpoke, KCNMA1). In this review, we first highlight the physiological importance of this ubiquitous channel, emphasizing the role that BK channels play in different channelopathies. We next discuss the modular nature of BK channel-forming protein, in which the different modules (the voltage sensor and the Ca2+ binding sites) communicate with the pore gates allosterically. In this regard, we review in detail the allosteric models proposed to explain channel activation and how the models are related to channel structure. Considering their extremely large conductance and unique selectivity to K+, we also offer an account of how these two apparently paradoxical characteristics can be understood consistently in unison, and what we have learned about the conduction system and the activation gates using ions, blockers, and toxins. Attention is paid here to the molecular nature of the voltage sensor and the Ca2+ binding sites that are located in a gating ring of known crystal structure and constituted by four COOH termini. Despite the fact that BK channels are coded by a single gene, diversity is obtained by means of alternative splicing and modulatory β and γ subunits. We finish this review by describing how the association of the α subunit with β or with γ subunits can change the BK channel phenotype and pharmacology.
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Affiliation(s)
- Ramon Latorre
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Karen Castillo
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Willy Carrasquel-Ursulaez
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Romina V. Sepulveda
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Fernando Gonzalez-Nilo
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Carlos Gonzalez
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Osvaldo Alvarez
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
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Li Y, Brayden JE. Rho kinase activity governs arteriolar myogenic depolarization. J Cereb Blood Flow Metab 2017; 37:140-152. [PMID: 26661251 PMCID: PMC5363734 DOI: 10.1177/0271678x15621069] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 11/10/2015] [Accepted: 11/11/2015] [Indexed: 11/15/2022]
Abstract
Cerebral arterioles contribute critically to regulation of local and global blood flow within the brain. Dysfunction of these blood vessels is implicated in numerous cardiovascular diseases. However, treatments are limited due to incomplete understanding of fundamental control mechanisms at this level of circulation. Emerging evidence points to a key role of Rho-associated protein kinase in regulation of microvascular contractility. This study sought to decipher the mechanisms of Rho-associated protein kinase-mediated myogenic vasoconstriction in cerebral parenchymal arterioles. Here, we report that the Rho-associated protein kinase inhibitor H1152 strongly attenuated pressure-induced constriction, cytosolic [Ca2+] increases, and depolarization of isolated parenchymal arterioles. Further, the RhoA activator CN03 potentiated parenchymal arteriole myogenic constriction and depolarization, indicating important involvement of RhoA/Rho-associated protein kinase signaling in myogenic excitation-contraction mechanisms. Because of the well-established role of TRPM4 in pressure-induced depolarization, possible modulatory effects of Rho-associated protein kinase on TRPM4 currents were explored using patch clamp electrophysiology. TRPM4 currents were suppressed by H1152 and enhanced by CN03. Finally, H1152 elevated the apparent [Ca2+]-threshold for TRPM4 activation, suggesting that Rho-associated protein kinase activates TRPM4 by increasing its Ca2+-sensitivity. Our results support a novel mechanism whereby Rho-associated protein kinase-mediated myogenic vasoconstriction occurs primarily through activation of TRPM4 channels, smooth muscle depolarization, and cytosolic [Ca2+] increases in cerebral arterioles.
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Affiliation(s)
- Yao Li
- Department of Pharmacology, University of Vermont, Burlington, VT, USA
| | - Joseph E Brayden
- Department of Pharmacology, University of Vermont, Burlington, VT, USA
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