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Corro-Hernández R, Aguila-Torres O, Rios A, Escalante B, Santana-Solano J. Computer-assisted image analysis of agonist-mediated microvascular constriction response in mouse cremaster muscle. PLoS One 2022; 17:e0277851. [PMID: 36395282 PMCID: PMC9671433 DOI: 10.1371/journal.pone.0277851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 11/03/2022] [Indexed: 11/18/2022] Open
Abstract
In this work, we implemented an automated method using a correlation coefficient to select a time interval with a minimum movement or rest interval, together with analysis of variance for measurement of blood vessel diameter in the cremaster muscle. Video images binarization using analysis of variance resulted in an enhanced and a clearly defined vessel wall. Histamine (1 mM) induced a marked reduction in vascular diameter (vasoconstriction) in the cremaster muscle from mice fed with standard (SD) and high fat diet (HFD). However, the effect of histamine was reduced in HFD mice compared to SD mice. Thus, the change in vascular diameter was 87.14% ± 7.44% and 52.63% ± 16.27% in SD and HFD mice, respectively. In conclusion, determination of a rest interval with minimal movement and the use of analysis of variance resulted useful to evaluate vascular diameter in small arteries. We suggest this method to streamline experiments facilitating cardiovascular research.
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Affiliation(s)
- Ricardo Corro-Hernández
- Centro de Investigación y de Estudios Avanzados del IPN, Unidad Monterrey, Apodaca, Nuevo León, México
| | - Oscar Aguila-Torres
- Centro de Investigación y de Estudios Avanzados del IPN, Unidad Monterrey, Apodaca, Nuevo León, México
| | - Amelia Rios
- Centro de Investigación y de Estudios Avanzados del IPN, Unidad Monterrey, Apodaca, Nuevo León, México
- * E-mail:
| | - Bruno Escalante
- Centro de Investigación y de Estudios Avanzados del IPN, Unidad Monterrey, Apodaca, Nuevo León, México
| | - Jesús Santana-Solano
- Centro de Investigación y de Estudios Avanzados del IPN, Unidad Monterrey, Apodaca, Nuevo León, México
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Phan TX, Ton HT, Gulyás H, Pórszász R, Tóth A, Russo R, Kay MW, Sahibzada N, Ahern GP. TRPV1 in arteries enables a rapid myogenic tone. J Physiol 2022; 600:1651-1666. [PMID: 35020949 PMCID: PMC8976781 DOI: 10.1113/jp281873] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 01/11/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS We explored the physiological role of TRPV1 in vascular smooth muscle. TRPV1 antagonists dilated skeletal muscle arterioles both ex vivo and in vivo, increased coronary perfusion and decreased systemic blood pressure. Stretch of arteriolar myocytes and increases in intraluminal pressure in arteries triggered rapid Ca2+ signaling and vasoconstriction respectively. Pharmacologic and/or genetic disruption of TRPV1 significantly inhibited the magnitude and rate of these responses. Furthermore, disrupting TRPV1 blunted the rapid vasodilation evoked by arterial constriction. Pharmacological experiments identified key roles for phospholipase C and protein kinase C, combined with temperature, in TRPV1-dependent arterial tone. These results show that TRPV1 in arteriolar myocytes dynamically regulates myogenic tone and blood flow in the heart and skeletal muscle. ABSTRACT Arterioles maintain blow flow by adjusting their diameter in response to changes in local blood pressure. In this process called the myogenic response, a vascular smooth muscle mechanosensor controls tone predominantly through altering the membrane potential. In general, myogenic responses occur slowly (minutes). In the heart and skeletal muscle, however, tone is activated rapidly (tens of seconds) and terminated by brief (100 ms) arterial constrictions. Previously, we identified extensive expression of TRPV1 in the smooth muscle of arterioles supplying skeletal muscle, heart and fat. Here we reveal a critical role for TRPV1 in the rapid myogenic tone of these tissues. TRPV1 antagonists dilated skeletal muscle arterioles in vitro and in vivo, increased coronary flow in isolated hearts, and transiently decreased blood pressure. All of these pharmacologic effects were abolished by genetic disruption of TRPV1. Stretch of isolated vascular smooth muscle cells or raised intravascular pressure in arteries triggered Ca2+ signaling and vasoconstriction. The majority of these stretch-responses were TRPV1-mediated, with the remaining tone being inhibited by the TRPM4 antagonist, 9-phenantrol. Notably, tone developed more quickly in arteries from wild-type compared with TRPV1-null mice. Furthermore, the immediate vasodilation following brief constriction of arterioles depended on TRPV1, consistent with a rapid deactivation of TRPV1. Pharmacologic experiments revealed that membrane stretch activates phospholipase C/protein kinase C signaling combined with heat to activate TRPV1, and in turn, L-type Ca2+ channels. These results suggest a critical role, for TRPV1 in the dynamic regulation of myogenic tone and blood flow in the heart and skeletal muscle. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Thieu X Phan
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC, USA.,Department of Biology, Vinh University, Vinh City, Vietnam
| | - Hoai T Ton
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC, USA.,Department of Biology, Vinh University, Vinh City, Vietnam
| | - Hajnalka Gulyás
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Debrecen, Doctoral School of Pharmaceutical Sciences, Debrecen, Hungary
| | - Róbert Pórszász
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Debrecen, Doctoral School of Pharmaceutical Sciences, Debrecen, Hungary
| | - Attila Tóth
- Division of Clinical Physiology, Institute of Cardiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Rebekah Russo
- Department of Biomedical Engineering, George Washington University, Washington, DC, USA
| | - Matthew W Kay
- Department of Biomedical Engineering, George Washington University, Washington, DC, USA
| | - Niaz Sahibzada
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC, USA
| | - Gerard P Ahern
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC, USA
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Wang Y, Zhang J, Wier WG, Chen L, Blaustein MP. NO-induced vasodilation correlates directly with BP in smooth muscle-Na/Ca exchanger-1-engineered mice: elevated BP does not attenuate endothelial function. Am J Physiol Heart Circ Physiol 2021; 320:H221-H237. [PMID: 33124883 PMCID: PMC7847073 DOI: 10.1152/ajpheart.00487.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 10/26/2020] [Accepted: 10/26/2020] [Indexed: 12/29/2022]
Abstract
Arterial smooth muscle Na+/Ca2+ exchanger-1 (SM-NCX1) promotes vasoconstriction or vasodilation by mediating, respectively, Ca2+ influx or efflux. In vivo, SM-NCX1 mediates net Ca2+ influx to help maintain myogenic tone (MT) and neuronally activated constriction. SM-NCX1-TG (overexpressing transgenic) mice have increased MT and mean blood pressure (MBP; +13.5 mmHg); SM-NCX1-KO (knockout) mice have reduced MT and MBP (-11.1 mmHg). Endothelium-dependent vasodilation (EDV) is often impaired in hypertension. We tested whether genetically engineered SM-NCX1 expression and consequent BP changes similarly alter EDV. Isolated, pressurized mesenteric resistance arteries with MT from SM-NCX1-TG and conditional SM-NCX1-KO mice, and femoral arteries in vivo from TG mice were studied. Acetylcholine (ACh)-dilated TG arteries with MT slightly more than control or KO arteries, implying that SM-NCX1 overexpression does not impair EDV. In preconstricted KO, but not TG mouse arteries, however, ACh- and bradykinin-triggered vasodilation was markedly attenuated. To circumvent the endothelium, phenylephrine-constricted resistance arteries were tested with Na-nitroprusside [SNP; nitric oxide (NO) donor] and cGMP. This endothelium-independent vasodilation was augmented in TG but attenuated in KO arteries that lack NCX1-mediated Ca2+ clearance. Baseline cytosolic Ca2+ ([Ca2+]cyt) was elevated in TG femoral arteries in vivo, supporting the high BP; furthermore, SNP-triggered [Ca2+]cyt decline and vasodilation were augmented as NO and cGMP promote myocyte polarization thereby enhancing NCX1-mediated Ca2+ efflux. The TG mouse data indicate that BP elevation does not attenuate endothelium-dependent vasodilation. Thus, in essential hypertension and many models the endothelial impairment that supports the hypertension apparently is not triggered by BP elevation but by extravascular mechanisms.NEW & NOTEWORTHY Endothelium-dependent, ACh-induced vasodilation (EDV) is attenuated, and arterial myocyte Na+/Ca2+ exchangers (NCX1) are upregulated in many forms of hypertension. Surprisingly, mildly hypertensive smooth muscle-specific (SM)-NCX1 transgenic mice exhibited modestly enhanced EDV and augmented endothelium-independent vasodilation (EIV). Conversely, mildly hypotensive SM-NCX1-knockout mice had greatly attenuated EIV. These adaptations help compensate for NCX1 expression-induced alterations in cytosolic Ca2+ and blood pressure (BP) and belie the view that elevated BP, itself, causes the endothelial dysregulation in hypertension.
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Affiliation(s)
- Youhua Wang
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
- Department of Physical Education, Shaanxi Normal University, Xi'an, Shaanxi, China
| | - Jin Zhang
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - W Gil Wier
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Ling Chen
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Mordecai P Blaustein
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
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Cellular and Ionic Mechanisms of Arterial Vasomotion. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1124:297-312. [DOI: 10.1007/978-981-13-5895-1_12] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Jackson WF, Boerman EM. Voltage-gated Ca 2+ channel activity modulates smooth muscle cell calcium waves in hamster cremaster arterioles. Am J Physiol Heart Circ Physiol 2018; 315:H871-H878. [PMID: 29957015 DOI: 10.1152/ajpheart.00292.2018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Cremaster muscle arteriolar smooth muscle cells (SMCs) display inositol 1,4,5-trisphosphate receptor-dependent Ca2+ waves that contribute to global myoplasmic Ca2+ concentration and myogenic tone. However, the contribution made by voltage-gated Ca2+ channels (VGCCs) to arteriolar SMC Ca2+ waves is unknown. We tested the hypothesis that VGCC activity modulates SMC Ca2+ waves in pressurized (80 cmH2O/59 mmHg, 34°C) hamster cremaster muscle arterioles loaded with Fluo-4 and imaged by confocal microscopy. Removal of extracellular Ca2+ dilated arterioles (32 ± 3 to 45 ± 3 μm, n = 15, P < 0.05) and inhibited the occurrence, amplitude, and frequency of Ca2+ waves ( n = 15, P < 0.05), indicating dependence of Ca2+ waves on Ca2+ influx. Blockade of VGCCs with nifedipine (1 μM) or diltiazem (10 μM) or deactivation of VGCCs by hyperpolarization of smooth muscle with the K+ channel agonist cromakalim (10 μM) produced similar inhibition of Ca2+ waves ( P < 0.05). Conversely, depolarization of SMCs with the K+ channel blocker tetraethylammonium (1 mM) constricted arterioles from 26 ± 3 to 14 ± 2 μm ( n = 11, P < 0.05) and increased wave occurrence (9 ± 3 to 16 ± 3 waves/SMC), amplitude (1.6 ± 0.07 to 1.9 ± 0.1), and frequency (0.5 ± 0.1 to 0.9 ± 0.2 Hz, n = 10, P < 0.05), effects that were blocked by nifedipine (1 μM, P < 0.05). Similarly, the VGCC agonist Bay K8644 (5 nM) constricted arterioles from 14 ± 1 to 8 ± 1 μm and increased wave occurrence (3 ± 1 to 10 ± 1 waves/SMC) and frequency (0.2 ± 0.1 to 0.6 ± 0.1 Hz, n = 6, P < 0.05), effects that were unaltered by ryanodine (50 μM, n = 6, P > 0.05). These data support the hypothesis that Ca2+ waves in arteriolar SMCs depend, in part, on the activity of VGCCs. NEW & NOTEWORTHY Arterioles that control blood flow to and within skeletal muscle depend on Ca2+ influx through voltage-gated Ca2+ channels and release of Ca2+ from internal stores through inositol 1,4,5-trisphosphate receptors in the form of Ca2+ waves to maintain pressure-induced smooth muscle tone.
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Affiliation(s)
- William F Jackson
- Department of Pharmacology and Toxicology, Michigan State University , East Lansing, Michigan
| | - Erika M Boerman
- Department of Pharmacology and Toxicology, Michigan State University , East Lansing, Michigan
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Imaging sympathetic neurogenic Ca 2+ signaling in blood vessels. Auton Neurosci 2017; 207:59-66. [PMID: 28781164 DOI: 10.1016/j.autneu.2017.07.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 06/20/2017] [Accepted: 07/27/2017] [Indexed: 12/30/2022]
Abstract
We review the information that has been provided by optical imaging experiments directed at understanding the role and effects of sympathetic nerve activity (SNA) in the functioning of blood vessels. Earlier studies utilized electric field stimulation of nerve terminals (EFS) in isolated arteries and vascular tissues (ex vivo) to elicit SNA, but more recently, imaging studies have been conducted in vivo, enabling the study of SNA in truly physiological conditions. Ex vivo: In vascular smooth muscle cells (VSMC) of isolated arteries, the three sympathetic neurotransmitters, norepinephrine (NE), ATP and neuropeptide Y (NPY), elicit or modulate distinct patterns of Ca2+ signaling, as revealed by confocal imaging of exogenous fluorescent Ca2+ indicators. Purinergic junctional Ca2+ transients (jCaTs) arise from Ca2+ influx during excitatory junction potentials (eJPs), and are associated with the initial neurogenic contraction. Adrenergic Ca2+ waves and oscillations cause contraction while SNA-induced endothelial Ca2+ 'pulsars' cause relaxation. In vivo: optical biosensor mice, which express genetically encoded Ca2+ indicators (GECI's) specifically in smooth muscle, combined with non-invasive imaging techniques has enabled imaging SNA-induced Ca2+ signaling and arterial diameter in vivo. SNA induces Ca2+ oscillations in intact arteries. [Ca2+] of arterial smooth muscle cells increased in hypertension, in association with increased SNA. High resolution imaging has revealed local sympathetic, neurogenic Ca2+ signaling within smooth muscle and endothelial cells of the vasculature. The ongoing development of in vivo imaging together with an expanding availability of different biosensor animals promises to enable the further assessment of SNA and its effects in the vasculature of living animals.
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7
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Jackson WF, Boerman EM. Regional heterogeneity in the mechanisms of myogenic tone in hamster arterioles. Am J Physiol Heart Circ Physiol 2017; 313:H667-H675. [PMID: 28667050 DOI: 10.1152/ajpheart.00183.2017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 06/07/2017] [Accepted: 06/26/2017] [Indexed: 01/30/2023]
Abstract
Myogenic tone is an important feature of arterioles and resistance arteries, but the mechanisms responsible for this hallmark characteristic remain unclear. We used pharmacological inhibitors to compare the roles played by phospholipase C (PLC; 10 μM U73122), inositol 1,4,5-trisphosphate receptors (IP3Rs; 100 μM 2-aminoethoxydiphenylborane), protein kinase C (10 μM bisindolylmaleimide I), angiotensin II type 1 receptors (1 μM losartan), Rho kinase (10 nM-30 μM Y27632 or 300 nM H1152), stretch-activated ion channels (10 nM-1 μM Gd3+ or 5 μM spider venom toxin GsMTx-4) and L-type voltage-gated Ca2+ channels (0.3-100 μM diltiazem) in myogenic tone of cannulated, pressurized (80 cmH2O), second-order hamster cremaster or cheek pouch arterioles. Effective inhibition of either PLC or IP3Rs dilated cremaster arterioles, inhibited Ca2+ waves, and reduced global Ca2+ levels. In contrast, cheek pouch arterioles did not display Ca2+ waves and inhibition of PLC or IP3Rs had no effect on myogenic tone or intracellular Ca2+ levels. Inhibition of Rho kinase dilated both cheek pouch and cremaster arterioles with equal efficacy and potency but also reduced intracellular Ca2+ signals in both arterioles. Similarly, inhibition of mechanosensitive ion channels with Gd2+ or GsMTx-4 produced comparable dilation in both arterioles. Inhibition of L-type Ca2+ channels with diltiazem was more effective in dilating cremaster (86 ± 5% dilation, n = 4) than cheek pouch arterioles (54 ± 4% dilation, n = 6, P < 0.05). Thus, there are substantial differences in the mechanisms underlying myogenic tone in hamster cremaster and cheek pouch arterioles. Regional heterogeneity in myogenic mechanisms could provide new targets for drug development to improve regional blood flow in a tissue-specific manner.NEW & NOTEWORTHY Regional heterogeneity in the mechanisms of pressure-induced myogenic tone implies that resistance vessels may be able to alter myogenic signaling pathways to adapt to their environment. A better understanding of the spectrum of myogenic mechanisms could provide new targets to treat diseases that affect resistance artery and arteriolar function.
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Affiliation(s)
- William F Jackson
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
| | - Erika M Boerman
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
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8
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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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Botti M, Ragionieri L, Cacchioli A, Gazza F, Panu R. Neurochemical Features of the Autonomic Neurons Projecting to the Cremaster Muscle of the Boar. Anat Rec (Hoboken) 2015; 298:2091-7. [DOI: 10.1002/ar.23271] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 07/13/2015] [Indexed: 12/20/2022]
Affiliation(s)
- Maddalena Botti
- Department of Veterinary Sciences; University of Parma; Parma 43126 Italy
| | - Luisa Ragionieri
- Department of Veterinary Sciences; University of Parma; Parma 43126 Italy
| | - Antonio Cacchioli
- Department of Veterinary Sciences; University of Parma; Parma 43126 Italy
| | - Ferdinando Gazza
- Department of Veterinary Sciences; University of Parma; Parma 43126 Italy
| | - Rino Panu
- Department of Veterinary Sciences; University of Parma; Parma 43126 Italy
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Mauban JRH, Zacharia J, Fairfax S, Wier WG. PC-PLC/sphingomyelin synthase activity plays a central role in the development of myogenic tone in murine resistance arteries. Am J Physiol Heart Circ Physiol 2015; 308:H1517-24. [PMID: 25888510 DOI: 10.1152/ajpheart.00594.2014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Accepted: 04/03/2015] [Indexed: 11/22/2022]
Abstract
Myogenic tone is an intrinsic property of the vasculature that contributes to blood pressure control and tissue perfusion. Earlier investigations assigned a key role in myogenic tone to phospholipase C (PLC) and its products, inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG). Here, we used the PLC inhibitor, U-73122, and two other, specific inhibitors of PLC subtypes (PI-PLC and PC-PLC) to delineate the role of PLC in myogenic tone of pressurized murine mesenteric arteries. U-73122 inhibited depolarization-induced contractions (high external K(+) concentration), thus confirming reports of nonspecific actions of U-73122 and its limited utility for studies of myogenic tone. Edelfosine, a specific inhibitor of PI-PLC, did not affect depolarization-induced contractions but modulated myogenic tone. Because PI-PLC produces IP3, we investigated the effect of blocking IP3 receptor-mediated Ca(2+) release on myogenic tone. Incubation of arteries with xestospongin C did not affect tone, consistent with the virtual absence of Ca(2+) waves in arteries with myogenic tone. D-609, an inhibitor of PC-PLC and sphingomyelin synthase, strongly inhibited myogenic tone and had no effect on depolarization-induced contraction. D-609 appeared to act by lowering cytoplasmic Ca(2+) concentration to levels below those that activate contraction. Importantly, incubation of pressurized arteries with a membrane-permeable analog of DAG induced vasoconstriction. The results therefore mandate a reexamination of the signaling pathways activated by the Bayliss mechanism. Our results suggest that PI-PLC and IP3 are not required in maintaining myogenic tone, but DAG, produced by PC-PLC and/or SM synthase, is likely through multiple mechanisms to increase Ca(2+) entry and promote vasoconstriction.
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Affiliation(s)
- Joseph R H Mauban
- Department of Physiology, School of Medicine, University of Maryland Baltimore, Baltimore, Maryland
| | - Joseph Zacharia
- Department of Physiology, School of Medicine, University of Maryland Baltimore, Baltimore, Maryland
| | - Seth Fairfax
- Department of Physiology, School of Medicine, University of Maryland Baltimore, Baltimore, Maryland
| | - Withrow Gil Wier
- Department of Physiology, School of Medicine, University of Maryland Baltimore, Baltimore, Maryland
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Wang Y, Chen L, Li M, Cha H, Iwamoto T, Zhang J. Conditional knockout of smooth muscle sodium calcium exchanger type-1 lowers blood pressure and attenuates Angiotensin II-salt hypertension. Physiol Rep 2015; 3:3/1/e12273. [PMID: 25626872 PMCID: PMC4387742 DOI: 10.14814/phy2.12273] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The functions of smooth muscle sodium calcium exchanger (NCX) in the vasculature are controversial and poorly understood. To determine the possible roles of NCX in the vascular phenotype and function, we developed a novel mouse model (SM‐NCX1 KO) in which the smooth muscle‐specific NCX type‐1 (NCX1) was conditionally knocked out using tamoxifen‐inducible Cre‐loxP recombination technique. SM‐NCX1 KO mice exhibit significantly lower blood pressure and attenuated angiotensin II (Ang II)‐salt‐induced hypertension (measured by radio telemetry and intra‐arterial catheterization). Isolated, pressurized mesenteric small resistance arteries from SM‐NCX1 KO mice, compared to control arteries, were characterized by the following: (1) ~90% reduced NCX1 protein expression; (2) impaired functional responses to (i) acute NCX inhibition by SEA0400 or SN‐6, (ii) NCX activation by low [Na+]o, and (iii) Na+ pump inhibition by ouabain; (3) attenuated myogenic reactivity; and (4) attenuated vasoconstrictor response to phenylephrine but not Ang II. These results provided direct evidence that arterial NCX1 normally mediates net Ca2+ influx that helps maintain basal vascular tone in small resistance arteries and blood pressure under physiological conditions. Importantly, NCX1 contributes to blood pressure elevation in Ang II‐salt hypertension, possibly by regulating α‐adrenergic receptor activation. Smooth muscle‐specific Na/Ca exchanger type‐1 in adult mice was knocked out by the tamoxifen‐inducible Cre‐LoxP technique 3–5 weeks before experiments. This results in (1) attenuated myogenic response and attenuated vasoconstrictor response to alpha‐adrenoceptor activation in pressurized mesenteric small resistance arteries; and (2) lower baseline blood pressure and reduced angiotensin II‐salt‐induced hypertension.
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Affiliation(s)
- Youhua Wang
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Ling Chen
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Meng Li
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Helen Cha
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Takahiro Iwamoto
- Department of Pharmacology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
| | - Jin Zhang
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA
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12
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Thunemann M, Schmidt K, de Wit C, Han X, Jain RK, Fukumura D, Feil R. Correlative intravital imaging of cGMP signals and vasodilation in mice. Front Physiol 2014; 5:394. [PMID: 25352809 PMCID: PMC4196583 DOI: 10.3389/fphys.2014.00394] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 09/23/2014] [Indexed: 01/09/2023] Open
Abstract
Cyclic guanosine monophosphate (cGMP) is an important signaling molecule and drug target in the cardiovascular system. It is well known that stimulation of the vascular nitric oxide (NO)-cGMP pathway results in vasodilation. However, the spatiotemporal dynamics of cGMP signals themselves and the cGMP concentrations within specific cardiovascular cell types in health, disease, and during pharmacotherapy with cGMP-elevating drugs are largely unknown. To facilitate the analysis of cGMP signaling in vivo, we have generated transgenic mice that express fluorescence resonance energy transfer (FRET)-based cGMP sensor proteins. Here, we describe two models of intravital FRET/cGMP imaging in the vasculature of cGMP sensor mice: (1) epifluorescence-based ratio imaging in resistance-type vessels of the cremaster muscle and (2) ratio imaging by multiphoton microscopy within the walls of subcutaneous blood vessels accessed through a dorsal skinfold chamber. Both methods allow simultaneous monitoring of NO-induced cGMP transients and vasodilation in living mice. Detailed protocols of all steps necessary to perform and evaluate intravital imaging experiments of the vasculature of anesthetized mice including surgery, imaging, and data evaluation are provided. An image segmentation approach is described to estimate FRET/cGMP changes within moving structures such as the vessel wall during vasodilation. The methods presented herein should be useful to visualize cGMP or other biochemical signals that are detectable with FRET-based biosensors, such as cyclic adenosine monophosphate or Ca2+, and to correlate them with respective vascular responses. With further refinement and combination of transgenic mouse models and intravital imaging technologies, we envision an exciting future, in which we are able to “watch” biochemistry, (patho-)physiology, and pharmacotherapy in the context of a living mammalian organism.
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Affiliation(s)
- Martin Thunemann
- Interfakultäres Institut für Biochemie, University of Tübingen Tübingen, Germany
| | | | - Cor de Wit
- Institut für Physiologie, Universität zu Lübeck Lübeck, Germany
| | - Xiaoxing Han
- Edwin L. Steele Laboratory, Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School Boston, MA, USA
| | - Rakesh K Jain
- Edwin L. Steele Laboratory, Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School Boston, MA, USA
| | - Dai Fukumura
- Edwin L. Steele Laboratory, Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School Boston, MA, USA
| | - Robert Feil
- Interfakultäres Institut für Biochemie, University of Tübingen Tübingen, Germany
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13
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Fairfax ST, Mauban JRH, Hao S, Rizzo MA, Zhang J, Wier WG. Ca(2+) signaling in arterioles and small arteries of conscious, restrained, optical biosensor mice. Front Physiol 2014; 5:387. [PMID: 25339912 PMCID: PMC4188025 DOI: 10.3389/fphys.2014.00387] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 09/18/2014] [Indexed: 01/23/2023] Open
Abstract
Two-photon fluorescence microscopy and conscious, restrained optical biosensor mice were used to study smooth muscle Ca2+ signaling in ear arterioles. Conscious mice were used in order to preserve normal mean arterial blood pressure (MAP) and sympathetic nerve activity (SNA). ExMLCK mice, which express a genetically-encoded smooth muscle-specific FRET-based Ca2+ indicator, were equipped with blood pressure telemetry and immobilized for imaging. MAP was 101 ± 4 mmHg in conscious restrained mice, similar to the freely mobile state (107 ± 3 mmHg). Oscillatory vasomotion or irregular contractions were observed in most arterioles (71%), with the greatest oscillatory frequency observed at 0.25 s−1. In a typical arteriole with an average diameter of ~35 μm, oscillatory vasomotion of a 5–6 μm magnitude was accompanied by nearly uniform [Ca2+] oscillations from ~0.1 to 0.5 μM, with maximum [Ca2+] occurring immediately before the rapid decrease in diameter. Very rapid, spatially uniform “Ca2+ flashes” were also observed but not asynchronous propagating Ca2+ waves. In contrast, vasomotion and dynamic Ca2+ signals were rarely observed in ear arterioles of anesthetized exMLCK biosensor mice. Hexamethonium (30 μg/g BW, i.p.) caused a fall in MAP to 74 ± 4 mmHg, arteriolar vasodilation, and abolition of vasomotion and synchronous Ca2+ transients. Summary: MAP and heart rate (HR) were normal during high-resolution Ca2+ imaging of conscious, restrained mice. SNA induced continuous vasomotion and irregular vasoconstrictions via spatially uniform Ca2+ signaling within the arterial wall. FRET-based biosensor mice and two-photon imaging provided the first measurements of [Ca2+] in vascular smooth muscle cells in arterioles of conscious animals.
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Affiliation(s)
- Seth T Fairfax
- Department of Physiology, University of Maryland School of Medicine Baltimore, MD, USA
| | - Joseph R H Mauban
- Department of Physiology, University of Maryland School of Medicine Baltimore, MD, USA
| | - Scarlett Hao
- Department of Physiology, University of Maryland School of Medicine Baltimore, MD, USA
| | - Mark A Rizzo
- Department of Physiology, University of Maryland School of Medicine Baltimore, MD, USA
| | - Jin Zhang
- Department of Physiology, University of Maryland School of Medicine Baltimore, MD, USA
| | - W Gil Wier
- Department of Physiology, University of Maryland School of Medicine Baltimore, MD, USA
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14
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Affiliation(s)
- W Gil Wier
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
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15
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Mauban JRH, Fairfax ST, Rizzo MA, Zhang J, Wier WG. A method for noninvasive longitudinal measurements of [Ca2+] in arterioles of hypertensive optical biosensor mice. Am J Physiol Heart Circ Physiol 2014; 307:H173-81. [PMID: 24858846 DOI: 10.1152/ajpheart.00182.2014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We used two-photon (2-p) Förster resonance energy transfer (FRET) microscopy to provide serial, noninvasive measurements of [Ca(2+)] in arterioles of living "biosensor" mice. These express a genetically encoded Ca(2+) indicator (GECI), either FRET-based exMLCK or intensity-based GCaMP2. The FRET ratios, Rmin and Rmax, required for in vivo Ca(2+) calibration of exMLCK were obtained in isolated arteries. For in vivo experiments, mice were anesthetized (1.5% isoflurane), and arterioles within a depilated ear were visualized through the intact skin (i.e., noninvasively), by 2-p excitation of exMLCK (at 820 nm) or GCaMP2 (at 920 nm). Spontaneous or agonist-evoked [Ca(2+)] transients in arteriolar smooth muscle cells were imaged (at 2 Hz) with both exMLCK and GCaMP2. To examine changes in arteriolar [Ca(2+)] that might accompany hypertension, five exMLCK mice were implanted with telemetric blood pressure transducers and osmotic minipumps containing ANG II (350 ng·kg(-1)·min(-1)) and fed a high (6%)-salt diet for 9 days. [Ca(2+)] was measured every other day in five smooth muscle cells of two to three arterioles in each animal. Prior to ANG II/salt, [Ca(2+)] was 246 ± 42 nM. [Ca(2+)] increased transiently to 599 nM on day 2 after beginning ANG II/salt, then remained elevated at 331 ± 42 nM for 4 more days, before returning to 265 ± 47 nM 6 days after removal of ANG II/salt. In summary, two-photon excitation of exMLCK and GCaMP2 provides a method for noninvasive, longitudinal quantification of [Ca(2+)] dynamics and vascular structure in individual arterioles of a particular animal over an extended period of time, a capability that should enhance future studies of hypertension and vascular function.
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Affiliation(s)
- Joseph R H Mauban
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Seth T Fairfax
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Mark A Rizzo
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Jin Zhang
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Withrow Gil Wier
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
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16
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Earley S. Smooth muscle cell Ca²⁺: think locally, act globally. Microcirculation 2013; 20:279-80. [PMID: 23421765 DOI: 10.1111/micc.12049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Accepted: 02/15/2013] [Indexed: 02/03/2023]
Abstract
Dynamic changes in intracellular Ca²⁺ levels in vascular smooth muscle cells are critically important for cardiovascular regulation. This Special Topic Issue highlights a series of expert opinion articles focused on this important subject. After a brief overview, novel discoveries surrounding smooth muscle cell Ca²⁺ influx via L-type and T-type channels are reviewed. Current work revealing the functional importance of dynamic Ca²⁺ signaling in the control of the parenchymal microvasculature and the emerging role of mitochondrial Ca²⁺ signaling and store-operated Ca²⁺ entry in smooth muscle cells is discussed. Finally, recent data describing a new target of localized Ca²⁺ signaling in arterial myocytes that is responsible for membrane depolarization is reviewed. Authors were encouraged to write in an opinionated and provocative manner with the hope of stimulating discussion in this area of research.
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Affiliation(s)
- Scott Earley
- Vascular Physiology Research Group, Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA.
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17
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Amberg GC, Navedo MF. Calcium dynamics in vascular smooth muscle. Microcirculation 2013; 20:281-9. [PMID: 23384444 DOI: 10.1111/micc.12046] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 01/31/2013] [Indexed: 12/31/2022]
Abstract
Smooth muscle cells are ultimately responsible for determining vascular luminal diameter and blood flow. Dynamic changes in intracellular calcium are a critical mechanism regulating vascular smooth muscle contractility. Processes influencing intracellular calcium are therefore important regulators of vascular function with physiological and pathophysiological consequences. In this review we discuss the major dynamic calcium signals identified and characterized in vascular smooth muscle cells. These signals vary with respect to their mechanisms of generation, temporal properties, and spatial distributions. The calcium signals discussed include calcium waves, junctional calcium transients, calcium sparks, calcium puffs, and L-type calcium channel sparklets. For each calcium signal we address underlying mechanisms, general properties, physiological importance, and regulation.
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Affiliation(s)
- Gregory C Amberg
- Vascular Physiology Research Group, Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA.
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18
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Hill MA, Meininger GA. Should we be sympathetic to angiotensin II infusion? J Physiol 2013; 591:5269-70. [DOI: 10.1113/jphysiol.2013.264895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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Wang Y, Chen L, Wier WG, Zhang J. Intravital Förster resonance energy transfer imaging reveals elevated [Ca2+]i and enhanced sympathetic tone in femoral arteries of angiotensin II-infused hypertensive biosensor mice. J Physiol 2013; 591:5321-36. [PMID: 23981717 DOI: 10.1113/jphysiol.2013.257808] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Artery narrowing in hypertension can only result from structural remodelling of the artery, or increased smooth muscle contraction. The latter may occur with, or without, increases in [Ca(2+)]i. Here, we sought to measure, in living hypertensive mice, possible changes in artery dimensions and/or [Ca(2+)]i, and to determine some of the mechanisms involved. Ca(2+)/calmodulin biosensor (Förster resonance energy transfer-based) mice were made hypertensive by s.c. infusion of angiotensin II (Ang II, 400 ng kg(-1) min(-1), 2-3 weeks). Intravital fluorescence microscopy was used to determine [Ca(2+)]i and outer diameter of surgically exposed, intact femoral artery (FA) of anaesthetized mice. Active contractile FA 'tone' was calculated from the basal-state diameter and the passive (i.e. Ca(2+)-free) diameter (PD). Compared to saline control, FAs of Ang II-infused mice had (1) ∼21% higher active tone and (2) ∼78 nm higher smooth muscle [Ca(2+)]i, but (3) the same PDs. The local Ang II receptor (AT1R) blocker losartan had negligible effect on tone or [Ca(2+)]i in control FAs, but reduced the basal tone by ∼9% in Ang II FAs. Both i.v. hexamethonium and locally applied prazosin abolished the difference in FA tone and [Ca(2+)]i, suggesting a dominant role of sympathetic nerve activity (SNA). Changes in diameter and [Ca(2+)]i in response to locally applied phenylephrine, Ang II, arginine vasopressin, elevated [K(+)]o and acetylcholine were not altered. In summary, FAs of living Ang II hypertensive mice have higher [Ca(2+)]i, and are more constricted, due, primarily, to elevated SNA and some increased arterial AT1R activation. Evidence of altered artery reactivity or remodeling was not found.
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Affiliation(s)
- Youhua Wang
- J. Zhang: Department of Physiology, University of Maryland School of Medicine, 655 W. Baltimore Street, Baltimore, MD 21201, USA.
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Zacharia J, Mauban JRH, Raina H, Fisher SA, Wier WG. High vascular tone of mouse femoral arteries in vivo is determined by sympathetic nerve activity via α1A- and α1D-adrenoceptor subtypes. PLoS One 2013; 8:e65969. [PMID: 23776582 PMCID: PMC3680395 DOI: 10.1371/journal.pone.0065969] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Accepted: 05/02/2013] [Indexed: 02/04/2023] Open
Abstract
Background and purpose Determining the role of vascular receptors in vivo is difficult and not readily accomplished by systemic application of antagonists or genetic manipulations. Here we used intravital microscopy to measure the contributions of sympathetic receptors, particularly α1-adrenoceptor subtypes, to contractile activation of femoral artery in vivo. Experimental approach Diameter and intracellular calcium ([Ca2+]i) in femoral arteries were determined by intravital fluorescence microscopy in mice expressing a Myosin Light Chain Kinase (MLCK) based calcium-calmodulin biosensor. Pharmacological agents were applied locally to the femoral artery to determine the contributions of vascular receptors to tonic contraction and [Ca2+]i,. Key results In the anesthetized animal, femoral arteries were constricted to a diameter equal to 54% of their passive diameter (i.e. tone = 46%). Of this total basal tone, 16% was blocked by RS79948 (0.1 µM) and thus attributable to α2-adrenoceptors. A further 46% was blocked by prazosin (0.1 µM) and thus attributable to α1-adrenoceptors. Blockade of P2X and NPY1 receptors with suramin (0.5 mM) and BIBP3226 (1.0 µM) respectively, reduced tone by a further 22%, leaving 16% of basal tone unaffected at these concentrations of antagonists. Application of RS100329 (α1A-selective antagonist) and BMY7378 (α1D-selective) decreased tone by 29% and 26%, respectively, and reduced [Ca2+]i. Chloroethylclonidine (1 µM preferential for α1B-) had no effect. Abolition of sympathetic nerve activity (hexamethonium, i.p.) reduced basal tone by 90%. Conclusion and Implications Tone of mouse femoral arteries in vivo is almost entirely sympathetic in origin. Activation of α1A- and α1D-adrenoceptors elevates [Ca2+]i and accounts for at least 55% of the tone.
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Affiliation(s)
- Joseph Zacharia
- University of Maryland, School of Medicine, Baltimore, Maryland, United States of America.
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