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Zhang YY, Li JZ, Xie HQ, Jin YX, Wang WT, Zhao B, Jia JM. High-resolution vasomotion analysis reveals novel arteriole physiological features and progressive modulation of cerebral vascular networks by stroke. J Cereb Blood Flow Metab 2024:271678X241258576. [PMID: 38820436 DOI: 10.1177/0271678x241258576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 06/02/2024]
Abstract
Spontaneous cerebral vasomotion, characterized by ∼0.1 Hz rhythmic contractility, is crucial for brain homeostasis. However, our understanding of vasomotion is limited due to a lack of high-precision analytical methods to determine single vasomotion events at basal levels. Here, we developed a novel strategy that integrates a baseline smoothing algorithm, allowing precise measurements of vasodynamics and concomitant Ca2+ dynamics in mouse cerebral vasculature imaged by two-photon microscopy. We identified several previously unrecognized vasomotion properties under different physiological and pathological conditions, especially in ischemic stroke, which is a highly harmful brain disease that results from vessel occlusion. First, the dynamic characteristics between SMCs Ca2+ and corresponding arteriolar vasomotion are correlated. Second, compared to previous diameter-based estimations, our radius-based measurements reveal anisotropic vascular movements, enabling a more precise determination of the latency between smooth muscle cell (SMC) Ca2+ activity and vasoconstriction. Third, we characterized single vasomotion event kinetics at scales of less than 4 seconds. Finally, following pathological vasoconstrictions induced by ischemic stroke, vasoactive arterioles entered an inert state and persisted despite recanalization. In summary, we developed a highly accurate technique for analyzing spontaneous vasomotion, and our data suggested a potential strategy to reduce stroke damage by promoting vasomotion recovery.
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Affiliation(s)
- Yi-Yi Zhang
- College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
- Key Laboratory of Growth Regulation and Translation Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, China
| | - Jin-Ze Li
- Key Laboratory of Growth Regulation and Translation Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, China
| | - Hui-Qi Xie
- Key Laboratory of Growth Regulation and Translation Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, China
| | - Yu-Xiao Jin
- Key Laboratory of Growth Regulation and Translation Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, China
| | - Wen-Tao Wang
- Key Laboratory of Growth Regulation and Translation Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, China
| | - Bingrui Zhao
- Key Laboratory of Growth Regulation and Translation Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, China
| | - Jie-Min Jia
- Key Laboratory of Growth Regulation and Translation Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, China
- Laboratory of Neurovascular Biology, Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, China
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, China
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Niizawa T, Sakuraba R, Kusaka T, Kurihara Y, Sugashi T, Kawaguchi H, Kanno I, Masamoto K. Spatiotemporal analysis of blood plasma and blood cell flow fluctuations of cerebral microcirculation in anesthetized rats. J Cereb Blood Flow Metab 2023; 43:138-152. [PMID: 36138557 PMCID: PMC9875347 DOI: 10.1177/0271678x221125743] [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: 01/15/2022] [Revised: 08/09/2022] [Accepted: 08/13/2022] [Indexed: 01/28/2023]
Abstract
Cerebral hemodynamics fluctuates spontaneously over broad frequency ranges. However, its spatiotemporal coherence of flow oscillations in cerebral microcirculation remains incompletely understood. The objective of this study was to characterize the spatiotemporal fluctuations of red blood cells (RBCs) and plasma flow in the rat cerebral microcirculation by simultaneously imaging their dynamic behaviors. Comparisons of changes in cross-section diameters between RBC and plasma flow showed dissociations in penetrating arterioles. The results indicate that vasomotion has the least effect on the lateral movement of circulating RBCs, resulting in variable changes in plasma layer thickness. Parenchymal capillaries exhibited slow fluctuations in RBC velocity (0.1 to 0.3 Hz), regardless of capillary diameter fluctuations (<0.1 Hz). Temporal fluctuations and the velocity of RBCs decreased significantly at divergent capillary bifurcations. The results indicate that a transit of RBCs generates flow resistance in the capillaries and that slow velocity fluctuations of the RBCs are subject to a number of bifurcations. In conclusion, the high-frequency oscillation of the blood flow is filtered at the bifurcation through the capillary networks. Therefore, a number of bifurcations in the cerebral microcirculation may contribute to the power of low-frequency oscillations.
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Affiliation(s)
- Tomoya Niizawa
- Faculty of Informatics and Engineering, University of
Electro-Communications, Tokyo, Japan
| | - Ruka Sakuraba
- Faculty of Informatics and Engineering, University of
Electro-Communications, Tokyo, Japan
| | - Tomoya Kusaka
- Faculty of Informatics and Engineering, University of
Electro-Communications, Tokyo, Japan
| | - Yuika Kurihara
- Faculty of Informatics and Engineering, University of
Electro-Communications, Tokyo, Japan
| | - Takuma Sugashi
- Faculty of Informatics and Engineering, University of
Electro-Communications, Tokyo, Japan
- Center for Neuroscience and Biomedical Engineering,
University of Electro-Communications, Tokyo, Japan
| | - Hiroshi Kawaguchi
- Human Informatics and Interaction Research Institute,
National Institute of Advanced Industrial Science and Technology
(AIST), Ibaraki, Japan
| | - Iwao Kanno
- Department of Functional Brain Imaging Research,
National Institute of Radiological Sciences, Chiba, Japan
| | - Kazuto Masamoto
- Faculty of Informatics and Engineering, University of
Electro-Communications, Tokyo, Japan
- Center for Neuroscience and Biomedical Engineering,
University of Electro-Communications, Tokyo, Japan
- Department of Functional Brain Imaging Research,
National Institute of Radiological Sciences, Chiba, Japan
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Role of Pericytes in the Initiation and Propagation of Spontaneous Activity in the Microvasculature. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1124:329-356. [PMID: 31183834 DOI: 10.1007/978-981-13-5895-1_14] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The microvasculature is composed of arterioles, capillaries and venules. Spontaneous arteriolar constrictions reduce effective vascular resistance to enhance tissue perfusion, while spontaneous venular constrictions facilitate the drainage of tissue metabolites by pumping blood. In the venules of visceral organs, mural cells, i.e. smooth muscle cells (SMCs) or pericytes, periodically generate spontaneous phasic constrictions, Ca2+ transients and transient depolarisations. These events arise from spontaneous Ca2+ release from the sarco-endoplasmic reticulum (SR/ER) and the subsequent opening of Ca2+-activated chloride channels (CaCCs). CaCC-dependent depolarisation further activates L-type voltage-dependent Ca2+ channels (LVDCCs) that play a critical role in maintaining the synchrony amongst mural cells. Mural cells in arterioles or capillaries are also capable of developing spontaneous activity. Non-contractile capillary pericytes generate spontaneous Ca2+ transients primarily relying on SR/ER Ca2+ release. Synchrony amongst capillary pericytes depends on gap junction-mediated spread of depolarisations resulting from the opening of either CaCCs or T-type VDCCs (TVDCCs) in a microvascular bed-dependent manner. The propagation of capillary Ca2+ transients into arterioles requires the opening of either L- or TVDCCs again depending on the microvascular bed. Since the blockade of gap junctions or CaCCs prevents spontaneous Ca2+ transients in arterioles and venules but not capillaries, capillary pericytes appear to play a primary role in generating spontaneous activity of the microvasculature unit. Pericytes in capillaries where the interchange of substances between tissues and the circulation takes place may provide the fundamental drive for upstream arterioles and downstream venules so that the microvasculature network functions as an integrated unit.
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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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5
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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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Kadekawa K, Majima T, Shimizu T, Wada N, de Groat WC, Kanai AJ, Goto M, Yoshiyama M, Sugaya K, Yoshimura N. The role of capsaicin-sensitive C-fiber afferent pathways in the control of micturition in spinal-intact and spinal cord-injured mice. Am J Physiol Renal Physiol 2017. [PMID: 28637786 DOI: 10.1152/ajprenal.00097.2017] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
We examined bladder and urethral sphincter activity in mice with or without spinal cord injury (SCI) after C-fiber afferent desensitization induced by capsaicin pretreatment and changes in electrophysiological properties of mouse bladder afferent neurons 4 wk after SCI. Female C57BL/6N mice were divided into four groups: 1) spinal intact (SI)-control, 2) SI-capsaicin pretreatment (Cap), 3) SCI-control, and 4) SCI-Cap groups. Continuous cystometry and external urethral sphincter (EUS)-electromyogram (EMG) were conducted under an awake condition. In the Cap groups, capsaicin (25, 50, or 100 mg/kg) was injected subcutaneously 4 days before the experiments. In the SI-Cap group, 100 mg/kg capsaicin pretreatment significantly increased bladder capacity and decreased the silent period duration of EUS/EMG compared with the SI-control group. In the SCI-Cap group, 50 and 100 mg/kg capsaicin pretreatment decreased the number of nonvoiding contractions (NVCs) and the duration of reduced EUS activity during voiding, respectively, compared with the SCI-control group. In SCI mice, hexamethonium, a ganglionic blocker, almost completely blocked NVCs, suggesting that they are of neurogenic origin. Patch-clamp recordings in capsaicin-sensitive bladder afferent neurons from SCI mice showed hyperexcitability, which was evidenced by decreased spike thresholds and increased firing rate compared with SI mice. These results indicate that capsaicin-sensitive C-fiber afferent pathways, which become hyperexcitable after SCI, can modulate bladder and urethral sphincter activity in awake SI and SCI mice. Detrusor overactivity as shown by NVCs in SCI mice is significantly but partially dependent on capsaicin-sensitive C-fiber afferents, whereas the EUS relaxation during voiding is enhanced by capsaicin-sensitive C-fiber bladder afferents in SI and SCI mice.
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Affiliation(s)
- Katsumi Kadekawa
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.,Southern Knights' Laboratory, Okinawa, Japan.,Okinawa Kyodo Hospital, Okinawa, Japan
| | - Tsuyoshi Majima
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.,Department of Urology, Nagoya University Graduate School of Medicine, Nagoya, Japan; and
| | - Takahiro Shimizu
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Naoki Wada
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - William C de Groat
- Department of Pharmacology and Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Anthony J Kanai
- Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Momokazu Goto
- Department of Urology, Nagoya University Graduate School of Medicine, Nagoya, Japan; and
| | - Mitsuharu Yoshiyama
- Department of Pharmacology and Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.,Department of Urology, University of Yamanashi Graduate School of Medical Science, Chuo, Japan
| | | | - Naoki Yoshimura
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; .,Department of Pharmacology and Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
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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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8
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Affiliation(s)
- Mark A Rizzo
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD
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9
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Chen L, Song H, Wang Y, Lee JC, Kotlikoff MI, Pritchard TJ, Paul RJ, Zhang J, Blaustein MP. Arterial α2-Na+ pump expression influences blood pressure: lessons from novel, genetically engineered smooth muscle-specific α2 mice. Am J Physiol Heart Circ Physiol 2015. [PMID: 26209057 DOI: 10.1152/ajpheart.00430.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Arterial myocytes express α1-catalytic subunit isoform Na(+) pumps (75-80% of total), which are ouabain resistant in rodents, and high ouabain affinity α2-Na(+) pumps. Mice with globally reduced α2-pumps (but not α1-pumps), mice with mutant ouabain-resistant α2-pumps, and mice with a smooth muscle (SM)-specific α2-transgene (α2 (SM-Tg)) that induces overexpression all have altered blood pressure (BP) phenotypes. We generated α2 (SM-DN) mice with SM-specific α2 (not α1) reduction (>50%) using nonfunctional dominant negative (DN) α2. We compared α2 (SM-DN) and α2 (SM-Tg) mice to controls to determine how arterial SM α2-pumps affect vasoconstriction and BP. α2 (SM-DN) mice had elevated basal mean BP (mean BP by telemetry: 117 ± 4 vs. 106 ± 1 mmHg, n = 7/7, P < 0.01) and enhanced BP responses to chronic ANG II infusion (240 ng·kg(-1)·min(-1)) and high (6%) NaCl. Several arterial Ca(2+) transporters, including Na(+)/Ca(2+) exchanger 1 (NCX1) and sarcoplasmic reticulum and plasma membrane Ca(2+) pumps [sarco(endo)plasmic reticulum Ca(2+)-ATPase 2 (SERCA2) and plasma membrane Ca(2+)-ATPase 1 (PMCA1)], were also reduced (>50%). α2 (SM-DN) mouse isolated small arteries had reduced myogenic reactivity, perhaps because of reduced Ca(2+) transporter expression. In contrast, α2 (SM-Tg) mouse aortas overexpressed α2 (>2-fold), NCX1, SERCA2, and PMCA1 (43). α2 (SM-Tg) mice had reduced basal mean BP (104 ± 1 vs. 109 ± 2 mmHg, n = 15/9, P < 0.02) and attenuated BP responses to chronic ANG II (300-400 ng·kg(-1)·min(-1)) with or without 2% NaCl but normal myogenic reactivity. NCX1 expression was inversely related to basal BP in SM-α2 engineered mice but was directly related in SM-NCX1 engineered mice. NCX1, which usually mediates arterial Ca(2+) entry, and α2-Na(+) pumps colocalize at plasma membrane-sarcoplasmic reticulum junctions and functionally couple via the local Na(+) gradient to help regulate cell Ca(2+). Altered Ca(2+) transporter expression in SM-α2 engineered mice apparently compensates to minimize Ca(2+) overload (α2 (SM-DN)) or depletion (α2 (SM-Tg)) and attenuate BP changes. In contrast, Ca(2+) transporter upregulation, observed in many rodent hypertension models, should enhance Ca(2+) entry and signaling and contribute significantly to BP elevation.
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Affiliation(s)
- Ling Chen
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland; Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Hong Song
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Youhua Wang
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Jane C Lee
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York
| | - Michael I Kotlikoff
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York
| | - Tracy J Pritchard
- College of Nursing, College of Medicine, University of Cincinnati, Cincinnati, Ohio; and
| | - Richard J Paul
- Department of Molecular and Cell Physiology, College of Medicine, University of Cincinnati, Cincinnati, Ohio
| | - Jin Zhang
- Department of Physiology, 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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Huo BX, Greene SE, Drew PJ. Venous cerebral blood volume increase during voluntary locomotion reflects cardiovascular changes. Neuroimage 2015; 118:301-12. [PMID: 26057593 DOI: 10.1016/j.neuroimage.2015.06.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 05/05/2015] [Accepted: 06/03/2015] [Indexed: 01/08/2023] Open
Abstract
Understanding how changes in the cardiovascular system contribute to cerebral blood flow (CBF) and volume (CBV) increases is critical for interpreting hemodynamic signals. Here we investigated how systemic cardiovascular changes affect the cortical hemodynamic response during voluntary locomotion. In the mouse, voluntary locomotion drives an increase in cortical CBF and arterial CBV that is localized to the forelimb/hindlimb representation in the somatosensory cortex, as well as a diffuse venous CBV increase. To determine if the heart rate increases that accompany locomotion contribute to locomotion-induced CBV and CBF increases, we occluded heart rate increases with the muscarinic cholinergic receptor antagonist glycopyrrolate, and reduced heart rate with the β1-adrenergic receptor antagonist atenolol. We quantified the effects of these cardiovascular manipulations on CBV and CBF dynamics by comparing the hemodynamic response functions (HRF) to locomotion across these conditions. Neither the CBF HRF nor the arterial component of the CBV HRF was significantly affected by pharmacological disruption of the heart rate. In contrast, the amplitude and spatial extent of the venous component of the CBV HRF were decreased by atenolol. These results suggest that the increase in venous CBV during locomotion was partially driven by peripheral cardiovascular changes, whereas CBF and arterial CBV increases associated with locomotion reflect central processes.
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Affiliation(s)
- Bing-Xing Huo
- Center for Neural Engineering Department of Engineering Science and Mechanics
| | - Stephanie E Greene
- Center for Neural Engineering Department of Engineering Science and Mechanics
| | - Patrick J Drew
- Center for Neural Engineering Department of Engineering Science and Mechanics; Department of Neurosurgery Pennsylvania State University, University Park, PA 16802, USA.
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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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