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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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Obesity Induces Artery-Specific Alterations: Evaluation of Vascular Function and Inflammatory and Smooth Muscle Phenotypic Markers. BIOMED RESEARCH INTERNATIONAL 2017; 2017:5038602. [PMID: 28466012 PMCID: PMC5390568 DOI: 10.1155/2017/5038602] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 03/19/2017] [Indexed: 02/06/2023]
Abstract
Vascular alterations are expected to occur in obese individuals but the impact of obesity could be different depending on the artery type. We aimed to evaluate the obesity effects on the relaxing and contractile responses and inflammatory and smooth muscle (SM) phenotypic markers in two vascular beds. Obesity was induced in C57Bl/6 mice by 16-week high-fat diet and vascular reactivity, mRNA expression of inflammatory and SM phenotypic markers, and collagen deposition were evaluated in small mesenteric arteries (SMA) and thoracic aorta (TA). Endothelium-dependent relaxation in SMA and TA was not modified by obesity. In contrast, contraction induced by depolarization and contractile agonists was reduced in SMA, whereas only contraction induced by adrenergic agonist was reduced in TA of obese mice. Obesity increased the mRNA expression of pro- and anti-inflammatory cytokines in SMA and TA. The expression of genes necessary for maintaining contractile ability was increased by obesity, but the increase was more pronounced in TA. Collagen deposition was increased in SMA, but not in TA, of obese mice. Although the endothelial function was still preserved, the SM of the two artery types was impaired by obesity, but the impairment was higher in SMA, which could be associated with SM phenotypic changes.
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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: 222] [Impact Index Per Article: 31.7] [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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Yang Z, Chen Y, Zhang Y, Jiang Y, Fang X, Xu J. Sevoflurane postconditioning against cerebral ischemic neuronal injury is abolished in diet-induced obesity: role of brain mitochondrial KATP channels. Mol Med Rep 2014; 9:843-50. [PMID: 24452205 DOI: 10.3892/mmr.2014.1912] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 01/06/2014] [Indexed: 12/13/2022] Open
Abstract
Obesity is associated with increased infarct volumes and adverse outcomes following ischemic stroke. However, its effect on anesthetic postconditioning‑induced neuroprotection has not been investigated. The present study examined the effect of sevoflurane postconditioning on focal ischemic brain injury in diet‑induced obesity. Sprague‑Dawley rats were fed a high‑fat diet (HF; 45% kcal as fat) for 12 weeks to develop obesity syndrome. Rats fed a low‑fat diet (LF; 10% kcal as fat) served as controls. The HF or LF‑fed rats were subjected to focal cerebral ischemia for 60 min, followed by 24 h of reperfusion. Postconditioning was performed by exposure to sevoflurane for 15 min immediately at the onset of reperfusion. The involvement of the mitochondrial KATP (mitoKATP) channel was analyzed by the administration of a selective inhibitor of 5‑hydroxydecanoate (5‑HD) prior to sevoflurane postconditioning or by administration of diazoxide (DZX), a mitoKATP channel opener, instead of sevoflurane. The cerebral infarct volume, neurological score and motor coordination were evaluated 24 h after reperfusion. The HF‑fed rats had larger infarct volumes, and lower neurological scores than the LF‑fed rats and also failed to respond to neuroprotection by sevoflurane or DZX. By contrast, sevoflurane and DZX reduced the infarct volumes and improved the neurological scores and motor coordination in the LF‑fed rats. Pretreatment with 5‑HD inhibited sevoflurane‑induced neuroprotection in the LF‑fed rats, whereas it had no effect in the HF‑fed rats. Molecular studies demonstrated that the expression of Kir6.2, a significant mitoKATP channel component, was reduced in the brains of the HF‑fed rats compared with the LF‑fed rats. The results of this study indicate that diet‑induced obesity eliminates the ability of anesthetic sevoflurane postconditioning to protect the brain against cerebral ischemic neuronal injury, most likely due to an impaired brain mitoKATP channel.
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Affiliation(s)
- Zecheng Yang
- Department of Surgery, Second Hospital, Jilin University, Changchun, Jilin 130041, P.R. China
| | - Yunbo Chen
- Department of Surgery, Second Hospital, Jilin University, Changchun, Jilin 130041, P.R. China
| | - Yan Zhang
- Department of Surgery, Second Hospital, Jilin University, Changchun, Jilin 130041, P.R. China
| | - Yi Jiang
- Department of Surgery, Second Hospital, Jilin University, Changchun, Jilin 130041, P.R. China
| | - Xuedong Fang
- Department of Surgery, Second Hospital, Jilin University, Changchun, Jilin 130041, P.R. China
| | - Jingwei Xu
- Department of Surgery, Second Hospital, Jilin University, Changchun, Jilin 130041, P.R. China
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Horrigan LA, Holohan CA, Lawless GA, Murtagh MA, Williams CT, Webster CM. Blueberry juice causes potent relaxation of rat aortic rings via the activation of potassium channels and the H₂S pathway. Food Funct 2013; 4:392-400. [PMID: 23175156 DOI: 10.1039/c2fo30205e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The objective of this study was to investigate the in vitro effects of blueberry juice on healthy rat aortic rings, and to explore the roles of potassium channels and of the hydrogen sulphide (H(2)S) pathway in mediating the effects of blueberry juice. Firstly, the antioxidant capacity of blueberry juice was compared to other popular juice drinks using the Folin-Ciocalteu and the DPPH assays. Blueberry juice had significantly higher total polyphenol content than any of the other drinks studied (p < 0.01). The effect of blueberry juice on noradrenaline-contracted aortic rings was then observed, and the juice caused significant inhibition of noradrenaline-induced contractions (p < 0.01). Voltage-gated potassium channel (Kv) blockers 4-aminopyridine (1 mM) and 3,4-diaminopyridine (1 mM), as well as the cystathionine γ-lysase (CSE) inhibitor d,l-propargylglycine (2 mM) were then utilised to elucidate the role of Kv channels and the CSE/H(2)S pathway. Kv channel blocker 3,4-diaminopyridine caused significant blockade at 1/100 and 1/50 dilutions of juice (p < 0.01), whilst 4-aminopyridine caused significant blockade of the 1/100 dilution of blueberry juice (p < 0.05). In addition, d,l-propargylglycine potently inhibited the effect of 1/100 and 1/50 dilutions of blueberry juice (p < 0.01). This study indicates that blueberry juice has potent vasorelaxing properties, and thus may be a useful dietary agent for the prevention and treatment of hypertension. This study also provides strong evidence that Kv channels and the CSE/H(2)S pathway may be responsible, at least in part, for mediating the effects of blueberry juice.
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Affiliation(s)
- Louise A Horrigan
- Physiology, School of Medicine, National University of Ireland, Galway, Ireland.
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Park WS, Hong DH, Son YK, Kim MH, Jeong SH, Kim HK, Kim N, Han J. Alteration of ATP-sensitive K+ channels in rabbit aortic smooth muscle during left ventricular hypertrophy. Am J Physiol Cell Physiol 2012; 303:C170-8. [PMID: 22572849 DOI: 10.1152/ajpcell.00041.2012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated the impairment of ATP-sensitive K(+) (K(ATP)) channels in aortic smooth muscle cells (ASMCs) from isoproterenol-induced hypertrophied rabbits. The amplitude of K(ATP) channels induced by the K(ATP) channel opener pinacidil (10 μM) was greater in ASMCs from control than from hypertrophied animals. In phenylephrine-preconstricted aortic rings, pinacidil induced relaxation in a dose-dependent manner. The dose-dependent curve was shifted to the right in the hypertrophied (EC(50): 17.80 ± 3.28 μM) compared with the control model (EC(50): 6.69 ± 2.40 μM). Although the level of Kir6.2 subtype expression did not differ between ASMCs from the control and hypertrophied models, those of the Kir6.1 and SUR2B subtypes were decreased in the hypertrophied model. Application of the calcitonin-gene related peptide (100 nM) and adenylyl cyclase activator forskolin (10 μM), which activates protein kinase A (PKA) and consequently K(ATP) channels, induced a K(ATP) current in both control and hypertrophied animals; however, the K(ATP) current amplitude did not differ between the two groups. Furthermore, PKA expression was not altered between the control and hypertrophied animals. These results suggests that the decreased K(ATP) current amplitude and K(ATP) channel-induced vasorelaxation in the hypertrophied animals were attributable to the reduction in K(ATP) channel expression but not to changes in the intracellular signaling mechanism that activates the K(ATP) current.
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Affiliation(s)
- Won Sun Park
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, Korea
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Zhang R, Niu H, Wang N, Sun L, Xu Y, Zhao R, Ban X, Yu Y, Yang B, Ai J. Daming capsule restores endothelial dysfunction induced by high-fat diet. Altern Ther Health Med 2012; 12:21. [PMID: 22443680 PMCID: PMC3383478 DOI: 10.1186/1472-6882-12-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 03/24/2012] [Indexed: 01/01/2023]
Abstract
BACKGROUND Daming capsule (DMC), a traditional Chinese formula, has a lipid-modulating action with reduced adverse side effects as compared with other lipid lowering compounds. Since endothelial dysfunction often accompanies the hyperlipidemic state, we hypothesize that DMC might restore endothelial dysfunction produced by a high-fat (HF) diet. Importantly, we also investigate possible mechanisms involved in mediating the effects of DMC on vascular reactivity. METHODS Rats were divided into four groups: control, HF diet, HF mixed DMC diet, HF mixed atorvastatin (ATV) diet. After 30 days, the thoracic cavity was exposed to remove the thoracic aorta for (i) histological examination; (ii) measurement of endothelial nitric oxide synthase (eNOS) by western blot; and (iii) tension study of thoracic aortic ring. RESULTS HF diet induced significant attenuation in the contraction and relaxation of rat aortic rings. Treatment with DMC significantly improved the relaxation of the aortic rings as compared with those from HF rats (P < 0.05), which was abolished by a nonspecific NOS inhibitor L-NAME. Moreover DMC significantly restored the decrease in eNOS expression induced by HF diet. Similar results were found in histopathologic changes. DMC failed to restore the loss of vasocontraction of aorta explained by an impairment of ATP-sensitive K+ channels (KATP) on the structure and/or function. DMC exerted the same protective effect as ATV, a positive control drug, on vascular injury produced by HF diet. CONCLUSION DMC partially protects the aorta from HF-induced endothelial dysfunction via upregulation of the expression of eNOS.
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Fadool DA, Tucker K, Pedarzani P. Mitral cells of the olfactory bulb perform metabolic sensing and are disrupted by obesity at the level of the Kv1.3 ion channel. PLoS One 2011; 6:e24921. [PMID: 21966386 PMCID: PMC3178571 DOI: 10.1371/journal.pone.0024921] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 08/19/2011] [Indexed: 12/12/2022] Open
Abstract
Sixty-five percent of Americans are over-weight. While the neuroendocrine controls of energy homeostasis are well known, how sensory systems respond to and are impacted by obesity is scantily understood. The main accepted function of the olfactory system is to provide an internal depiction of our external chemical environment, starting from the detection of chemosensory cues. We hypothesized that the system additionally functions to encode internal chemistry via the detection of chemicals that are important indicators of metabolic state. We here uncovered that the olfactory bulb (OB) subserves as an internal sensor of metabolism via insulin-induced modulation of the potassium channel Kv1.3. Using an adult slice preparation of the olfactory bulb, we found that evoked neural activity in Kv1.3-expressing mitral cells is enhanced following acute insulin application. Insulin mediated changes in mitral cell excitability are predominantly due to the modulation of Kv1.3 channels as evidenced by the lack of effect in slices from Kv1.3-null mice. Moreover, a selective Kv1.3 peptide blocker (ShK186) inhibits more than 80% of the outward current in parallel voltage-clamp studies, whereby insulin significantly decreases the peak current magnitude without altering the kinetics of inactivation or deactivation. Mice that were chronically administered insulin using intranasal delivery approaches exhibited either an elevation in basal firing frequency or fired a single cluster of action potentials. Following chronic administration of the hormone, mitral cells were inhibited by application of acute insulin rather than excited. Mice made obese through a diet of ∼32% fat exhibited prominent changes in mitral cell action potential shape and clustering behavior, whereby the subsequent response to acute insulin stimulation was either attenuated or completely absent. Our results implicate an inappropriate neural function of olfactory sensors following exposure to chronic levels of the hormone insulin (diabetes) or increased body weight (obesity).
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Affiliation(s)
- Debra Ann Fadool
- Program in Neuroscience, The Florida State University, Tallahassee, Florida, United States of America
- Department of Biological Sciences, The Florida State University, Tallahassee, Florida, United States of America
- Institute of Molecular Biophysics, The Florida State University, Tallahassee, Florida, United States of America
- * E-mail:
| | - Kristal Tucker
- Program in Neuroscience, The Florida State University, Tallahassee, Florida, United States of America
| | - Paola Pedarzani
- Research Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
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