Whole cell current and membrane potential regulation by a human smooth muscle mechanosensitive calcium channel

2000 ◽  
Vol 279 (6) ◽  
pp. G1155-G1161 ◽  
Author(s):  
Adrian N. Holm ◽  
Adam Rich ◽  
Michael G. Sarr ◽  
Gianrico Farrugia
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Smooth Muscle Cells ◽  
Outward Current ◽  
Muscle Cells ◽  
Membrane Hyperpolarization ◽  
Whole Cell ◽  
Circular Smooth Muscle ◽  
Channel Current ◽  
Cell Current

Mechanotransduction is required for a wide variety of biological functions. The aim of this study was to determine the effect of activation of a mechanosensitive Ca2+ channel, present in human jejunal circular smooth muscle cells, on whole cell currents and on membrane potential. Currents were recorded using patch-clamp techniques, and perfusion of the bath (10 ml/min, 30 s) was used to mechanoactivate the L-type Ca2+ channel. Perfusion resulted in activation of L-type Ca2+ channels and an increase in outward current from 664 ± 57 to 773 ± 72 pA at +60 mV. Membrane potential hyperpolarized from −42 ± 4 to −50 ± 5 mV. In the presence of nifedipine (10 μM), there was no increase in outward current or change in membrane potential with perfusion. In the presence of charybdotoxin or iberiotoxin, perfusion of the bath did not increase outward current or change membrane potential. A model is proposed in which mechanoactivation of an L-type Ca2+ channel current in human jejunal circular smooth muscle cells results in increased Ca2+ entry and cell contraction. Ca2+ entry activates large-conductance Ca2+-activated K+channels, resulting in membrane hyperpolarization and relaxation.

Activation of whole cell currents in isolated human jejunal circular smooth muscle cells by carbon monoxide

1993 ◽  
Vol 264 (6) ◽  
pp. G1184-G1189 ◽  
Author(s):  
G. Farrugia ◽  
W. A. Irons ◽  
J. L. Rae ◽  
M. G. Sarr ◽  
J. H. Szurszewski
Keyword(s):  
Carbon Monoxide ◽  
Smooth Muscle ◽  
Membrane Potential ◽  
Muscle Cells ◽  
Patch Clamp Technique ◽  
Current Increase ◽  
Membrane Hyperpolarization ◽  
Whole Cell ◽  
Cell Current ◽  
Whole Cell Current

Carbon monoxide (CO) is a low molecular weight oxide produced endogenously from fatty acids and heme protein. A physiological role for CO has been suggested for vascular smooth muscle, hemostasis, and olfactory neurons, but direct evidence is lacking. Heme oxygenase, which catalyzes the formation of CO from heme proteins, is present in small intestinal smooth muscle. The effect of 1% CO on whole cell currents in normal human jejunal circular muscle cells was studied with the use of a perforated patch-clamp technique. A 1% CO-containing Krebs solution caused an initial and transient increase in whole cell current in 20 of 22 cells tested (175 +/- 40%, mean +/- SE) and a transient hyperpolarization (15.6 +/- 3.6 mV, mean +/- SE) of the membrane potential. During prolonged recordings, 1% CO evoked ongoing cyclic increases and decreases in the whole cell current. Each current increase was accompanied by a sharp membrane hyperpolarization. These data suggest that CO may modulate whole cell potassium current and membrane potential.

Role of HERG-like K+ currents in opossum esophageal circular smooth muscle

1999 ◽  
Vol 277 (6) ◽  
pp. C1284-C1290 ◽  
Author(s):  
Hamid I. Akbarali ◽  
Hemant Thatte ◽  
Xue Dao He ◽  
Wayne R. Giles ◽  
Raj K. Goyal
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Smooth Muscle Cells ◽  
Single Cells ◽  
Circular Muscle ◽  
Muscle Cells ◽  
Resting Membrane Potential ◽  
Channel Blockers ◽  
Circular Smooth Muscle ◽  
Inward Currents

An inwardly rectifying K+ conductance closely resembling the human ether-a-go-go-related gene (HERG) current was identified in single smooth muscle cells of opossum esophageal circular muscle. When cells were voltage clamped at 0 mV, in isotonic K+ solution (140 mM), step hyperpolarizations to −120 mV in 10-mV increments resulted in large inward currents that activated rapidly and then declined slowly (inactivated) during the test pulse in a time- and voltage- dependent fashion. The HERG K+ channel blockers E-4031 (1 μM), cisapride (1 μM), and La3+ (100 μM) strongly inhibited these currents as did millimolar concentrations of Ba2+. Immunoflourescence staining with anti-HERG antibody in single cells resulted in punctate staining at the sarcolemma. At membrane potentials near the resting membrane potential (−50 to −70 mV), this K+ conductance did not inactivate completely. In conventional microelectrode recordings, both E-4031 and cisapride depolarized tissue strips by 10 mV and also induced phasic contractions. In combination, these results provide direct experimental evidence for expression of HERG-like K+ currents in gastrointestinal smooth muscle cells and suggest that HERG plays an important role in modulating the resting membrane potential.

Abstract 2622: Serotonin And Endothelin Increase L-type Calcium Channel Current In Pulmonary Artery Smooth Muscle Cells, Unrelated To Changes In Membrane Potential

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Zhigang Hong ◽  
Jesus A Cabrera ◽  
Mohan Dutt ◽  
Basel Aloul ◽  
E. K Weir
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Smooth Muscle Cells ◽  
Calcium Channel ◽  
Calcium Current ◽  
Calcium Influx ◽  
Muscle Cells ◽  
Membrane Depolarization ◽  
Channel Current ◽  
Relationship Of

Serotonin (5-HT) and endothelin (ET-1) are both involved in the pathophysiology of idiopathic pulmonary arterial hypertension. In addition to the release of calcium (Ca ++ ) from the internal stores in the smooth muscle cells (SMCs), these agents stimulate entry of Ca ++ through the L-type Ca ++ channel. In isolated rat pulmonary resistance artery (PA) rings, 5-HT (10 μM) caused a contraction of 110 ± 14 % of the contraction elicited by 60 mM KCl. After inhibition of K V and K Ca channels by 4-AP and TEA, 5-HT caused a stronger contraction of 176 ± 4% (p<0.01). Consequently, we studied the relationship of 5-HT- stimulated contraction to membrane potential (E m ) and L-type calcium current in rat resistance PASMCs. Contrary to expectation, 5-HT (1, 10, 100 μM) had no effect on I K or E m (n=5 for each). However, 5-HT (10 μM) increased L-type calcium current between E m -20 and +30 mV (n=7). This effect was inhibited by a PKC blocker (BIS-1, 3 μM), which also caused a marked reduction of 5-HT-stimulated contraction of PA rings (>70% decrease at 10 μM 5-HT). In contrast to 5-HT, ET-1 (10 nM) reduced I K and caused membrane depolarization (from −41 ± 5 to −31 ± 3 mV, n=4). In addition to this effect, ET-1, like 5-HT, increased L-type calcium current over the same range of E m (n=7). This increase was inhibited by nifedipine (3 μM). These experiments indicate that both 5-HT and ET-1 increase calcium influx through the L-type calcium channel in a manner independent of E m . ET-1 has an additional effect of causing membrane depolarization, which also increases calcium entry through L-type channels by altering voltage gating of the channel.

Chronic carbon monoxide enhanced IbTx-sensitive currents in rat resistance pulmonary artery smooth muscle cells

2002 ◽  
Vol 283 (1) ◽  
pp. L120-L129 ◽  
Author(s):  
Eric Dubuis ◽  
Mathieu Gautier ◽  
Alexandre Melin ◽  
Manuel Rebocho ◽  
Catherine Girardin ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Smooth Muscle ◽  
Membrane Potential ◽  
Pulmonary Artery ◽  
Smooth Muscle Cells ◽  
Outward Current ◽  
Muscle Cells ◽  
Membrane Resistance ◽  
Resting Membrane Potential ◽  
Whole Cell Patch Clamp

Exogenous carbon monoxide (CO) can induce pulmonary vasodilation by acting directly on pulmonary artery (PA) smooth muscle cells. We investigated the contribution of K+ channels to the regulation of resistance PA resting membrane potential on control (PAC) rats and rats exposed to CO for 3 wk at 530 parts/million, labeled as PACO rats. Whole cell patch-clamp experiments revealed that the resting membrane potential of PACO cells was more negative than that of PAC cells. This was associated with a decrease of membrane resistance in PACO cells. Additional analysis showed that outward current density in PACO cells was higher (50% at +60 mV) than in PAC cells. This was linked to an increase of iberiotoxin (IbTx)-sensitive current. Chronic CO hyperpolarized membrane of pressurized PA from −46.9 ± 1.2 to −56.4 ± 2.6 mV. Additionally, IbTx significantly depolarized membrane of smooth muscle cells from PACO arteries but not from PAC arteries. The present study provides initial evidence of an increase of Ca2+-activated K+ current in smooth muscle cells from PA of rats exposed to chronic CO.

scholarly journals Muscarinic activation of transient inward current and contraction in canine colon circular smooth muscle cells

2001 ◽  
Vol 79 (1) ◽  
pp. 34-42
Author(s):  
A Molleman ◽  
L WC Liu ◽  
J D Huizinga
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscarinic Receptor ◽  
Outward Current ◽  
Cyclopiazonic Acid ◽  
Muscle Cells ◽  
Transient Outward Current ◽  
Inward Current ◽  
Circular Smooth Muscle ◽  
Transient Inward Current

Muscarinic receptor mediated membrane currents and contractions were studied in isolated canine colon circular smooth muscle cells. Carbachol (10–5M) evoked a slow transient inward current that was superimposed by a transient outward current at holding potentials greater than –50 mV. Carbachol contracted the cells by 70 ± 2%. The effects of carbachol were blocked by atropine (10–6M), tetraethyl ammonium (20 mM), and BAPTA-AM (25 mM applied for 20 min). The inward current and contraction were not sensitive to diltiazem (10–5M), nitrendipine (3 × 10–7M), niflumic acid (10–5M), or N-phenylanthranilic acid (10–4M), but were gradually inhibited after repetitive stimulations in Ca2+free solution. Ni2+(2 mM) inhibited the inward current by 67 ± 4%. The inward current reversed at +15 mV. The outward component could be selectively inhibited by iberiotoxin (20 nM) or by intracellular Cs+. Repeated stimulation in the presence of cyclopiazonic acid (CPA, 3 µM) inhibited the carbachol-induced outward current and partially inhibited contraction. CPA did not inhibit the inward current. In conclusion, muscarinic receptor stimulation evoked a CPA-sensitive calcium release that caused contraction and a CPA-insensitive transient inward current was activated that is primarily carried by Ca2+ions and is sensitive to Ni2+.Key words: calcium, carbachol, smooth muscle, cyclopiazonic acid, sarcoplasmic reticulum.

Nitric oxide modulates a calcium-activated potassium current in muscle cells from opossum esophagus

1995 ◽  
Vol 269 (4) ◽  
pp. G606-G612 ◽  
Author(s):  
J. A. Murray ◽  
E. F. Shibata ◽  
T. L. Buresh ◽  
H. Picken ◽  
B. W. O'Meara ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Smooth Muscle ◽  
Protein Kinase ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Protein Kinase G ◽  
Patch Clamp Technique ◽  
Whole Cell ◽  
Circular Smooth Muscle ◽  
K Current

Nitric oxide mediates nerve-induced hyperpolarization of circular smooth muscle of the esophagus. Two mechanisms are proposed to explain this hyperpolarization: an increase in K+ current or a decrease in Cl- current. These studies test the hypothesis that nitric oxide increases a K+ current in esophageal smooth muscle. Three outward K+ currents are present in circular smooth muscle cells from the opossum esophagus. One current is a Ca(2+)-activated K+ current (IKCa2+). This current is inhibited by charybdotoxin. Whole cell currents were recorded from isolated opossum esophageal smooth muscle cells using the whole cell patch-clamp technique. These studies showed that IKCa2+ is activated at potentials more positive than -30 mV. Bath application of S-nitroso-L-cysteine increased IKCa2+ by 50% above control levels throughout the entire activation range of potentials. The enhanced current was reversible on washout. Either charybdotoxin, an inhibitor of IKCa2+, or (R)-p-8-(4-chloropenylthio)-guanosine 3',5'-cyclic monophosphorothioate, an inhibitor of protein kinase G, antagonized the increase in outward current induced by S-nitroso-L-cysteine. These data suggest that nitric oxide activates IKCa2+ via the guanosine 3',5'-cyclic monophosphate-protein kinase G signal transduction pathway.

Effect of nitric oxide on calcium-activated potassium channels in colonic smooth muscle of rabbits

1998 ◽  
Vol 274 (5) ◽  
pp. G848-G856 ◽  
Author(s):  
Gang Lu ◽  
Bruno Mazet ◽  
Michael G. Sarr ◽  
Joseph H. Szurszewski
Keyword(s):  
Nitric Oxide ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Nerve Fibers ◽  
Nadph Diaphorase ◽  
Whole Cell ◽  
Circular Smooth Muscle ◽  
Rabbit Colon ◽  
Inside Out

Nitric oxide (NO) hyperpolarizes intestinal smooth muscle cells. This study was designed to determine the mechanism whereby NO activates KCa channels of circular smooth muscle of the rabbit colon. Transmural biopsies of the rabbit colon were stained for NADPH-diaphorase. Freshly dispersed circular smooth muscle cells were studied in the whole cell configuration, as well as in on-cell and excised inside-out patch recording configurations, while KCa current and the activity of KCa channels, respectively, were monitored. NADPH-diaphorase-positive nerve fibers were found in both muscle layers. NO (1%) increased whole cell net outward current by 79% and hyperpolarized resting membrane voltage from −59 to −73 mV ( n = 8 cells, P < 0.01). In the on-cell patch recording configuration, NO (0.5% or 1%) in the bath increased NP o of KCa channels; charybdotoxin (125 nM) in the pipette solution blocked this effect. In the excised inside-out patch recording configuration, NO (1%) had no effect on NP o of KCa channels. In the on-cell patch recording configuration, methylene blue (1 μM) or cystamine (5 mM) in the bath solution decreased the effect of NO (1%) on NP o of KCa channels. NP o was increased by 8-bromo-cGMP (8-BrcGMP; 1 mM), a cGMP analog, and zaprinast (100 μM), an inhibitor of cGMP phosphodiesterase. These data suggest that NO increased whole cell outward K+current by activating KCa channels through a cGMP pathway.

Membrane properties of smooth muscle cells in pulmonary arteries of the rat

1982 ◽  
Vol 242 (5) ◽  
pp. H900-H906 ◽  
Author(s):  
H. Suzuki ◽  
B. M. Twarog
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Pulmonary Artery ◽  
Smooth Muscle Cells ◽  
Main Pulmonary Artery ◽  
Pulmonary Arteries ◽  
Outward Current ◽  
Muscle Cells ◽  
Membrane Properties ◽  
Similar Degree

Electrical properties of the membrane of smooth muscle cells in the rat main pulmonary artery (MPA) and a small pulmonary artery (SPA) were compared. MPA and SPA differed in several important respects, suggesting characteristic quantitative and qualitative differences in membrane properties. 1) Resting membrane potentials were similar in both (MPA 52.2 +/- 1.3 mV; SPA 51.5 +/- 1.7 mV). The cells displayed no spontaneous electrical activity. The muscle layers in both MPA and SPA showed cablelike properties; a graded local response to outward current pulses was observed, but no action potentials were evoked. 2) Tetraethylammonium chloride (TEA, 1-5 mM) depolarized, increased membrane resistance, and suppressed rectification in MPA. TEA strongly depolarized SPA and contraction ensued. 3) The maximum membrane depolarization produced by a 10-fold increase in extracellular [K+] was 48 mV in MPA and 47 mV in SPA. In K+-free solution gradual depolarization was observed in SPA, but the membrane potential in MPA was not modified. Restoration of K+-containing solution produced equivalent hyperpolarization in both tissues, indicating a similar degree of stimulation of electrogenic Na+-K+ pumping. 4) A Na+-deficient solution did not affect the membrane potential in MPA but depolarized SPA.

Protein kinase C inhibits delayed rectifier K+ current in rabbit vascular smooth muscle cells

1996 ◽  
Vol 271 (1) ◽  
pp. H109-H119 ◽  
Author(s):  
E. A. Aiello ◽  
O. Clement-Chomienne ◽  
D. P. Sontag ◽  
M. P. Walsh ◽  
W. C. Cole
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Outward Current ◽  
Muscle Cells ◽  
Delayed Rectifier ◽  
Whole Cell ◽  
Kinase C

The effect of protein kinase C (PKC) activation on 4-aminopyridine (4-AP)-sensitive delayed rectifier current (IdK) was studied in isolated rabbit portal vein smooth muscle cells by use of standard whole cell voltage clamp. The effects of the phorbol ester, 4 beta-phorbol 12,13-dibutyrate (PdBu, 100 nM) and diacylglycerol analogues, 1,2-dioctanoyl-sn-glycerol (1,2-diC8, 10 microM) and 1,3-dioctanoyl-sn-glycerol (1,3-diC8, 10 microM), on macroscopic whole cell IdK were assessed in myocytes dialyzed with 10 mM 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) and 5 mM ATP (20-22 degrees C). Activation of PKC by 1,2-diC8 or PdBu caused a decline in IdK that was reversed with washout of drug. 1,2-diC8 had no effect on outward current present after exposure to 4-AP (20 mM). The inactive analogue, 1,3-diC8, did not affect IdK, but subsequent exposure to the active analogue, 1,2-diC8, caused a marked depression of the current. The inhibition of IdK by 1,2-diC8 was significantly reduced by intracellular dialysis with the inhibitors of PKC, chelerythrine (50 microM) and calphostin C (1 microM). Substitution of extracellular Ca2+ with Mg2+ in the presence of 10 mM intracellular BAPTA did not affect the suppression of IdK by 1,2-diC8, indicating the involvement of a Ca(2+)-independent isoform of PKC. This study suggests a novel signal transduction mechanism for inhibition of 4-AP-sensitive IdK involving a phosphotransferase reaction catalyzed by PKC in vascular smooth muscle myocytes.

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