ASIC-like Currents in Freshly Isolated Cerebral Artery Smooth Muscle Cells are Inhibited by Endogenous Oxidase Activity

Chung, Wen-Shuo; Farley, Jerry M.; Drummond, Heather A.

doi:10.1159/000325215

Cited by 14 publications

(10 citation statements)

References 37 publications

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“…Moreover, stomatin regulates the gating and localization of several types of ion channels, including acid-sensing ion channels (7,48), voltage-activated Ca 2ϩ (Ca V 2.1) channels (11), pannexins (70), and possibly epithelial Na ϩ channels (13) and aquaporins (53). In this regard, there is evidence that acid-sensing ion channels can be regulated by their redox state and by NADPH oxidases (2,9,10). Therefore, it is possible that the organizational features of the model shown in Fig.…”

Section: Discussionmentioning

confidence: 99%

NOX2 interacts with podocyte TRPC6 channels and contributes to their activation by diacylglycerol: essential role of podocin in formation of this complex

Kim

Anderson

Wilson

et al. 2013

American Journal of Physiology-Cell Physiology

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Canonical transient receptor potential-6 (TRPC6) channels have been implicated in the pathophysiology of glomerular diseases. TRPC6 channels are typically activated by diacylglycerol (DAG) during PLC-dependent transduction cascades. TRPC6 channels can also be activated by reactive oxygen species (ROS). We previously showed that podocin is required for DAG analogs to produce robust activation of TRPC6 channels in podocytes. Here we show that endogenous TRPC6 channels in immortalized podocytes reciprocally coimmunoprecipitate with the catalytic subunit of the NADPH oxidase NOX2 (gp91(phox)). The NOX2-TRPC6 interaction was not detected in cells stably expressing a short hairpin RNA targeting podocin, although NOX2 and TRPC6 were present at normal levels. Application of a membrane-permeable DAG analog [1-oleoyl-2-acetyl-sn-glycerol (OAG)] increased generation of ROS in podocytes, but this effect was not detected in podocin knockdown cells. OAG also increased steady-state surface expression of the NOX2 regulatory subunit p47(phox). In whole cell recordings, TRPC6 activation by OAG was reduced in podocytes pretreated with the NOX2 inhibitor apocynin, by the pan-NOX inhibitor diphenylene iodonium, and by tempol, a ROS quencher. Cholesterol depletion and disruption of lipid rafts by methyl-β-cyclodextrin reduced activation of podocyte TRPC6 channels by OAG and also eliminated the NOX2-TRPC6 interaction as assessed by coimmunoprecipitation. These data suggest that active NOX2 assembles with TRPC6 at podocin-organized sterol-rich raft domains and becomes catalytically active in response to DAG. The localized production of ROS contributes to TRPC6 activation by chemical stimuli such as DAG. Podocin appears to be necessary for assembly of the NOX2-TRPC6 complex in lipid rafts.

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Section: Discussionmentioning

confidence: 99%

NOX2 interacts with podocyte TRPC6 channels and contributes to their activation by diacylglycerol: essential role of podocin in formation of this complex

Kim

Anderson

Wilson

et al. 2013

American Journal of Physiology-Cell Physiology

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“…Whole cell currents were recorded using conventional patch-clamp techniques with an Axopatch 200B amplifier (Axon Instruments) interfaced to a PC through Digidata1440A digitizer (Axon Instruments) as previously described (4,5). Data were sampled at 5 kHz and filtered at 1 kHz using a low-pass Bessel filter.…”

Section: Methodsmentioning

confidence: 99%

βENaC is required for whole cell mechanically gated currents in renal vascular smooth muscle cells

Chung

Weissman

Farley

et al. 2013

American Journal of Physiology-Renal Physiology

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Chung WS, Weissman JL, Farley J, Drummond HA. ␤ENaC is required for whole cell mechanically gated currents in renal vascular smooth muscle cells. Am J Physiol Renal Physiol 304: F1428 -F1437, 2013. First published April 3, 2013 doi:10.1152/ajprenal.00444.2012.-Myogenic constrictor responses in small renal arteries and afferent arterioles are suppressed in mice with reduced levels of ␤-epithelial Na ϩ channel (␤ENaC m/m ). The underlying mechanism is unclear. Decreased activity of voltage-gated calcium channels (VGCC) or mechanically gated ion channels and increased activity of large conductance calcium-activated potassium (BK) channels are a few possible mechanisms. The purpose of this study was to determine if VGCC, BK, or mechanically gated ion channel activity was altered in renal vascular smooth muscle cell (VSMC) from ␤ENaC m/m mice. To address this, we used whole cell patch-clamp electrophysiological approaches in freshly isolated renal VSMCs. Compared with ␤ENaC ϩ/ϩ controls, the current-voltage relationships for VGCC and BK activity are similar in ␤ENaC m/m mice. These findings suggest neither VGCC nor BK channel dysfunction accounts for reduced myogenic constriction in ␤ENaC m/m mice. We then examined mechanically gated currents using a novel in vitro assay where VSMCs are mechanically activated by stretching an underlying elastomer. We found the mechanically gated currents, predominantly carried by Na ϩ , are observed with less frequency (87 vs. 43%) and have smaller magnitude (Ϫ54.1 Ϯ 12.5 vs. Ϫ20.9 Ϯ 4.9 pA) in renal VSMCs from ␤ENaC m/m mice. Residual currents are expected in this model since VSMC ␤ENaC expression is reduced by 50%. These findings suggest ␤ENaC is required for normal mechanically gated currents in renal VSMCs and their disruption may account for the reduced myogenic constriction in the ␤ENaC m/m model. Our findings are consistent with the role of ␤ENaC as a VSMC mechanosensor and function of evolutionarily related nematode degenerin proteins.epithelial Na ϩ channel; ion channel; degenerin; myogenic constriction THE MYOGENIC RESPONSE IS AN inherent property of small arteries and arterioles in certain organs, including the kidney. The myogenic response is characterized by vasoconstriction following an increase in intraluminal pressure and vasodilation following a decrease in intraluminal pressure. Myogenic constriction is a physiologically relevant response. In the kidney, it is an important mechanism of renal autoregulation, critical for maintaining normal renal blood flow and glomerular filtration rate with changes in perfusion pressure. Recent studies also suggest myogenic constriction plays an important role in protecting against pressure-related renal injury by preventing transmission of systemic pressure swings to delicate renal microvasculature (28,29,42).There are at least three ion channels that play important roles in the myogenic response; mechanically gated ion channels, voltage-gated calcium channels (VGCC), and large conductance calcium activated potassium (BK) channels...

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“…; Chung et al. ). However, the physiological importance of VSMC protongated ASIC1a containing channels in vascular function is still unclear.…”

Section: Introductionmentioning

confidence: 96%

“…Several recent studies suggest that ASIC1a containing proteins and channels are also expressed in vascular smooth muscle cells (VSMC) (Grifoni et al 2008a(Grifoni et al , 2008bJernigan et al 2009;Chung et al 2011). However, the physiological importance of VSMC protongated ASIC1a containing channels in vascular function is still unclear.…”

Section: Introductionmentioning

confidence: 99%

Enhanced maximal exercise capacity, vasodilation to electrical muscle contraction, and hind limb vascular density in ASIC1a null mice

et al. 2017

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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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ASIC-like Currents in Freshly Isolated Cerebral Artery Smooth Muscle Cells are Inhibited by Endogenous Oxidase Activity

Cited by 14 publications

References 37 publications

NOX2 interacts with podocyte TRPC6 channels and contributes to their activation by diacylglycerol: essential role of podocin in formation of this complex

NOX2 interacts with podocyte TRPC6 channels and contributes to their activation by diacylglycerol: essential role of podocin in formation of this complex

βENaC is required for whole cell mechanically gated currents in renal vascular smooth muscle cells

Enhanced maximal exercise capacity, vasodilation to electrical muscle contraction, and hind limb vascular density in ASIC1a null mice

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