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Garcia SM, Naik JS, Resta TC, Jernigan NL. Acid-sensing ion channel 1a activates IKCa/SKCa channels and contributes to endothelium-dependent dilation. J Gen Physiol 2023; 155:e202213173. [PMID: 36484717 PMCID: PMC9984545 DOI: 10.1085/jgp.202213173] [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: 04/12/2022] [Revised: 10/21/2022] [Accepted: 11/17/2022] [Indexed: 12/13/2022] Open
Abstract
Acid-sensing ion channel 1a (ASIC1a) belongs to a novel family of proton-gated cation channels that are permeable to both Na+ and Ca2+. ASIC1a is expressed in vascular smooth muscle and endothelial cells in a variety of vascular beds, yet little is known regarding the potential impact of ASIC1a to regulate local vascular reactivity. Our previous studies in rat mesenteric arteries suggest ASIC1a does not contribute to agonist-induced vasoconstriction but may mediate a vasodilatory response. The objective of the current study is to determine the role of ASIC1a in systemic vasodilatory responses by testing the hypothesis that the activation of endothelial ASIC1a mediates vasodilation of mesenteric resistance arteries through an endothelium-dependent hyperpolarization (EDH)-related pathway. The selective ASIC1a antagonist psalmotoxin 1 (PcTX1) largely attenuated the sustained vasodilatory response to acetylcholine (ACh) in isolated, pressurized mesenteric resistance arteries and ACh-mediated Ca2+ influx in freshly isolated mesenteric endothelial tubes. Similarly, basal tone was enhanced and ACh-induced vasodilation blunted in mesenteric arteries from Asic1a knockout mice. ASIC1a colocalizes with intermediate- and small-conductance Ca2+-activated K+ channels (IKCa and SKCa, respectively), and the IKCa/SKCa-sensitive component of the ACh-mediated vasodilation was blocked by ASIC1a inhibition. To determine the role of ASIC1a to activate IKCa/SKCa channels, we measured whole-cell K+ currents using the perforated-patch clamp technique in freshly isolated mesenteric endothelial cells. Inhibition of ASIC1a prevented ACh-induced activation of IKCa/SKCa channels. The ASIC1 agonist, α/β-MitTx, activated IKCa/SKCa channels and induced an IKCa/SKCa-dependent vasodilation. Together, the present study demonstrates that ASIC1a couples to IKCa/SKCa channels in mesenteric resistance arteries to mediate endothelium-dependent vasodilation.
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Affiliation(s)
- Selina M. Garcia
- Department of Cell Biology and Physiology University of New Mexico School of Medicine, Albuquerque, NM
| | - Jay S. Naik
- Department of Cell Biology and Physiology University of New Mexico School of Medicine, Albuquerque, NM
| | - Thomas C. Resta
- Department of Cell Biology and Physiology University of New Mexico School of Medicine, Albuquerque, NM
| | - Nikki L. Jernigan
- Department of Cell Biology and Physiology University of New Mexico School of Medicine, Albuquerque, NM
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2
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Butenas ALE, Rollins KS, Parr SK, Hammond ST, Ade CJ, Hageman KS, Musch TI, Copp SW. Novel mechanosensory role for acid sensing ion channel subtype 1a in evoking the exercise pressor reflex in rats with heart failure. J Physiol 2022; 600:2105-2125. [PMID: 35343594 PMCID: PMC9893514 DOI: 10.1113/jp282923] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 03/18/2022] [Indexed: 02/05/2023] Open
Abstract
Mechanical and metabolic signals associated with skeletal muscle contraction stimulate the sensory endings of thin fibre muscle afferents, which, in turn, generates reflex increases in sympathetic nerve activity (SNA) and blood pressure (the exercise pressor reflex; EPR). EPR activation in patients and animals with heart failure with reduced ejection fraction (HF-rEF) results in exaggerated increases in SNA and promotes exercise intolerance. In the healthy decerebrate rat, a subtype of acid sensing ion channel (ASIC) on the sensory endings of thin fibre muscle afferents, namely ASIC1a, has been shown to contribute to the metabolically sensitive portion of the EPR (i.e. metaboreflex), but not the mechanically sensitive portion of the EPR (i.e. the mechanoreflex). However, the role played by ASIC1a in evoking the EPR in HF-rEF is unknown. We hypothesized that, in decerebrate, unanaesthetized HF-rEF rats, injection of the ASIC1a antagonist psalmotoxin-1 (PcTx-1; 100 ng) into the hindlimb arterial supply would reduce the reflex increase in renal SNA (RSNA) evoked via 30 s of electrically induced static hindlimb muscle contraction, but not static hindlimb muscle stretch (model of mechanoreflex activation isolated from contraction-induced metabolite-production). We found that PcTx-1 reduced the reflex increase in RSNA evoked in response to muscle contraction (n = 8; mean (SD) ∫ΔRSNA pre: 1343 (588) a.u.; post: 816 (573) a.u.; P = 0.026) and muscle stretch (n = 6; ∫ΔRSNA pre: 688 (583) a.u.; post: 304 (370) a.u.; P = 0.025). Our data suggest that, in HF-rEF rats, ASIC1a contributes to activation of the exercise pressor reflex and that contribution includes a novel role for ASIC1a in mechanosensation that is not present in healthy rats. KEY POINTS: Skeletal muscle contraction results in exaggerated reflex increases in sympathetic nerve activity in heart failure patients compared to healthy counterparts, which likely contributes to increased cardiovascular risk and impaired tolerance for even mild exercise (i.e. activities of daily living) for patients suffering with this condition. Activation of acid sensing ion channel subtype 1a (ASIC1a) on the sensory endings of thin fibre muscle afferents during skeletal muscle contraction contributes to reflex increases in sympathetic nerve activity and blood pressure, at least in healthy subjects. In this study, we demonstrate that ASIC1a on the sensory endings of thin fibre muscle afferents plays a role in both the mechanical and metabolic components of the exercise pressor reflex in male rats with heart failure. The present data identify a novel role for ASIC1a in evoking the exercise pressor reflex in heart failure and may have important clinical implications for heart failure patients.
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Affiliation(s)
| | | | - Shannon K. Parr
- Department of Kinesiology, Kansas State University, Manhattan, KS, USA
| | | | - Carl J. Ade
- Department of Kinesiology, Kansas State University, Manhattan, KS, USA
| | - K. Sue Hageman
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, USA
| | - Timothy I. Musch
- Department of Kinesiology, Kansas State University, Manhattan, KS, USA,Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, USA
| | - Steven W. Copp
- Department of Kinesiology, Kansas State University, Manhattan, KS, USA
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3
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Ducrocq GP, Kim JS, Estrada JA, Kaufman MP. ASIC1a plays a key role in evoking the metabolic component of the exercise pressor reflex in rats. Am J Physiol Heart Circ Physiol 2020; 318:H78-H89. [PMID: 31675256 PMCID: PMC6985806 DOI: 10.1152/ajpheart.00565.2019] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 10/23/2019] [Accepted: 10/28/2019] [Indexed: 11/22/2022]
Abstract
The role of the acid-sensing ion channel 1a (ASIC1a) in evoking the exercise pressor reflex is unknown, despite the fact that ASIC1a is opened by decreases in pH in the physiological range. This fact prompted us to test the hypothesis that ASIC1a plays an important role in evoking the exercise pressor reflex in decerebrated rats with freely perfused hindlimb muscles. To test this hypothesis, we measured the effect of injecting two ASIC1a blockers into the arterial supply of the triceps surae muscles on the reflex pressor responses to four maneuvers, namely 1) static contraction of the triceps surae muscles (i.e., the exercise pressor reflex), 2) calcaneal tendon stretch, 3) intra-arterial injection of lactic acid, and 4) intra-arterial injection of diprotonated phosphate. We found that the 2 ASIC1a blockers, psalmotoxin-1 (200 ng/kg) and mambalgin-1 (6.5 μg/kg), decreased the pressor responses to static contraction as well as the peak pressor responses to injection of lactic acid and diprotonated phosphate. In contrast, neither ASIC1a blocker had any effect on the pressor responses to tendon stretch. Importantly, we found that ASIC1a blockade significantly decreased the pressor response to static contraction after a latency of at least 8 s. Our results support the hypothesis that ASIC1a plays a key role in evoking the metabolic component of the exercise pressor reflex.NEW & NOTEWORTHY The role played by acid-sensing ion channel 1a (ASIC1a) in evoking the exercise pressor reflex remains unknown. In decerebrated rats with freely perfused femoral arteries, blocking ASIC1a with psalmotoxin-1 or mambalgin-1 significantly attenuated the pressor response to static contraction, lactic acid, and diprotonated phosphate injection but had no effect on the pressor response to stretch. We conclude that ASIC1a plays a key role in evoking the exercise pressor reflex by responding to contraction-induced metabolites, such as protons.
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Affiliation(s)
- Guillaume P Ducrocq
- Heart and Vascular Institute, Penn State College of Medicine, Hershey, Pennsylvania
| | - Joyce S Kim
- Heart and Vascular Institute, Penn State College of Medicine, Hershey, Pennsylvania
| | - Juan A Estrada
- Heart and Vascular Institute, Penn State College of Medicine, Hershey, Pennsylvania
| | - Marc P Kaufman
- Heart and Vascular Institute, Penn State College of Medicine, Hershey, Pennsylvania
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Detweiler ND, Herbert LM, Garcia SM, Yan S, Vigil KG, Sheak JR, Resta TC, Walker BR, Jernigan NL. Loss of acid-sensing ion channel 2 enhances pulmonary vascular resistance and hypoxic pulmonary hypertension. J Appl Physiol (1985) 2019; 127:393-407. [PMID: 31169471 DOI: 10.1152/japplphysiol.00894.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Acid-sensing ion channels (ASICs) are voltage-insensitive cation channels that contribute to cellular excitability. We previously reported that ASIC1 in pulmonary artery smooth muscle cells (PASMC) contribute to pulmonary vasoreactivity and vascular remodeling during the development of chronic hypoxia (CH)-induced pulmonary hypertension. However, the roles of ASIC2 and ASIC3 in regulation of pulmonary vasoreactivity and the development of CH-induced pulmonary hypertension are unknown. We tested the hypothesis that ASIC2 and ASIC3 contribute to increased pulmonary vasoreactivity and development of CH-induced pulmonary hypertension using ASIC2- and ASIC3-knockout (-/-) mice. In contrast to this hypothesis, we found that ASIC2-/- mice exhibit enhanced CH-induced pulmonary hypertension compared with WT and ASIC3-/- mice. This response was not associated with a change in ventilatory sensitivity or systemic cardiovascular function but was instead associated with direct changes in pulmonary vascular reactivity and pulmonary arterial morphology in ASIC2-/- mice. This increase in reactivity correlated with enhanced pulmonary arterial basal tone, elevated basal PASMC [Ca2+] and store-operated calcium entry (SOCE) in PASMC from ASIC2-/- mice. This increase in PASMC [Ca2+] and vasoreactivity was dependent on ASIC1-mediated Ca2+ influx but was not contingent upon an increase in ASIC1 mRNA or protein expression in PASMC from ASIC2-/- mice. Together, the results from this study demonstrate an important role for ASIC2 to regulate pulmonary vascular reactivity and for ASIC2 to modulate the development of CH-induced pulmonary hypertension. These data further suggest that loss of ASIC2 enhances the contribution of ASIC1 to overall pulmonary vascular reactivity.NEW & NOTEWORTHY This study demonstrates that loss of ASIC2 leads to increased baseline pulmonary vascular resistance, enhanced responses to a variety of vasoconstrictor stimuli, and greater development of hypoxic pulmonary hypertension. Furthermore, these results suggest that loss of ASIC2 enhances the contribution of ASIC1 to pulmonary vascular reactivity.
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Affiliation(s)
- Neil D Detweiler
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center Albuquerque, New Mexico
| | - Lindsay M Herbert
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center Albuquerque, New Mexico
| | - Selina M Garcia
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center Albuquerque, New Mexico
| | - Simin Yan
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center Albuquerque, New Mexico
| | - Kenneth G Vigil
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center Albuquerque, New Mexico
| | - Joshua R Sheak
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center Albuquerque, New Mexico
| | - Thomas C Resta
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center Albuquerque, New Mexico
| | - Benjimen R Walker
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center Albuquerque, New Mexico
| | - Nikki L Jernigan
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center Albuquerque, New Mexico
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Drummond HA, Xiang L, Chade AR, Hester R. Enhanced maximal exercise capacity, vasodilation to electrical muscle contraction, and hind limb vascular density in ASIC1a null mice. Physiol Rep 2018; 5:5/15/e13368. [PMID: 28784852 PMCID: PMC5555894 DOI: 10.14814/phy2.13368] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 06/27/2017] [Accepted: 06/28/2017] [Indexed: 12/15/2022] Open
Abstract
Acid‐sensing ion channel (ASIC) proteins form extracellular proton‐gated, cation‐selective channels in neurons and vascular smooth muscle cells and are proposed to act as extracellular proton sensors. However, their importance to vascular responses under conditions associated with extracellular acidosis, such as strenuous exercise, is unclear. Therefore, the purpose of this study was to determine if one ASIC protein, ASIC1a, contributes to extracellular proton‐gated vascular responses and exercise tolerance. To determine if ASIC1a contributes to exercise tolerance, we determined peak oxygen (O2) uptake in conscious ASIC1a−/− mice during exhaustive treadmill running. Loss of ASIC1a was associated with a greater peak running speed (60 ± 2 vs. 53 ± 3 m·min−1, P = 0.049) and peak oxygen (O2) uptake during exhaustive treadmill running (9563 ± 120 vs. 8836 ± 276 mL·kg−1·h−1, n = 6–7, P = 0.0082). There were no differences in absolute or relative lean body mass, as determined by EchoMRI. To determine if ASIC1a contributes to vascular responses during muscle contraction, we measured femoral vascular conductance (FVC) during a stepwise electrical stimulation (0.5–5.0 Hz at 3 V for 60 sec) of the left major hind limb muscles. FVC increased to a greater extent in ASIC1a−/− versus ASIC1a+/+ mice (0.44 ± 0.03 vs. 0.30 ± 0.04 mL·min−1·100 g hind limb mass−1 · mmHg−1, n = 5 each, P = 0.0009). Vasodilation following local application of external protons in the spinotrapezius muscle increased the duration, but not the magnitude, of the vasodilatory response in ASIC1a−/− mice. Finally, we examined hind limb vascular density using micro‐CT and found increased density of 0–80 μm vessels (P < 0.05). Our findings suggest an increased vascular density and an enhanced vasodilatory response to local protons, to a lesser degree, may contribute to the enhanced vascular conductance and increased peak exercise capacity in ASIC1a−/− mice.
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Affiliation(s)
- Heather A Drummond
- Department of Physiology and Biophysics and the Center for Excellence in Cardiovascular-Renal Research, University of Mississippi Medical Center, Jackson, Mississippi
| | - Lusha Xiang
- Department of Physiology and Biophysics and the Center for Excellence in Cardiovascular-Renal Research, University of Mississippi Medical Center, Jackson, Mississippi
| | - Alejandro R Chade
- Department of Physiology and Biophysics and the Center for Excellence in Cardiovascular-Renal Research, University of Mississippi Medical Center, Jackson, Mississippi
| | - Robert Hester
- Department of Physiology and Biophysics and the Center for Excellence in Cardiovascular-Renal Research, University of Mississippi Medical Center, Jackson, Mississippi
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