scholarly journals Arecoline Hydrobromide Enhances Jejunum Smooth Muscle Contractility via Voltage-Dependent Potassium Channels in W/Wv Mice

2021 ◽  
pp. 437-446
Author(s):  
Q CHEN ◽  
Z JIANG ◽  
J ZHANG ◽  
L CAO ◽  
Z CHEN
Keyword(s):  
Smooth Muscle ◽  
Potassium Channels ◽  
Smooth Muscle Cells ◽  
Isometric Force ◽  
Muscle Cells ◽  
Resting Membrane Potential ◽  
Dependent Manner ◽  
Excitatory Effect ◽  
Patch Clamp Technique ◽  
Voltage Dependent

Gastrointestinal motility was disturbed in W/Wv, which were lacking of interstitial cells of Cajal (ICC). In this study, we have investigated the role of arecoline hydrobromide (AH) on smooth muscle motility in the jejunum of W/Wv and wild-type (WT) mice. The jejunum tension was recorded by an isometric force transducer. Intracellular recording was used to identify whether AH affects slow wave and resting membrane potential (RMP) in vitro. The whole-cell patch clamp technique was used to explore the effects of AH on voltage-dependent potassium channels for jejunum smooth muscle cells. AH enhanced W/Wv and WT jejunum contractility in a dose-dependent manner. Atropine and nicardipine completely blocked the excitatory effect of AH in both W/Wv and WT. TEA did not reduce the effect of AH in WT, but was sufficient to block the excitatory effect of AH in W/Wv. AH significantly depolarized the RMP of jejunum cells in W/Wv and WT. After pretreatment with TEA, the RMP of jejunum cells indicated depolarization in W/Wv and WT, but subsequently perfused AH had no additional effect on RMP. AH inhibited the voltage-dependent K+ currents of acutely isolated mouse jejunum smooth muscle cells. Our study demonstrate that AH enhances the contraction activity of jejunum smooth muscle, an effect which is mediated by voltage-dependent potassium channels that acts to enhance the excitability of jejunum smooth muscle cells in mice.

Voltage-dependent calcium channel current in isolated gallbladder smooth muscle cells of guinea pig

1993 ◽  
Vol 264 (6) ◽  
pp. G1066-G1076 ◽  
Author(s):  
T. Shimada
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Smooth Muscle Cells ◽  
Time Course ◽  
Reversal Potential ◽  
High Sensitivity ◽  
Muscle Cells ◽  
Patch Clamp Technique ◽  
Decay Component ◽  
Voltage Dependent

The voltage-dependent Ca2+ current was studied in enzymatically dispersed guinea pig gallbladder smooth muscle cells using the whole cell patch-clamp technique. Depolarizing voltage (V) steps induced an inward current (I) that was carried by Ca2+. The threshold potential was -40 to -30 mV, the maximal current was observed at +10 to +20 mV, and the reversal potential was around +80 mV. I-V curves obtained with holding potentials of -80 and -40 mV were not significantly different. This current had a high sensitivity to dihydropyridine drugs, and the Ba2+ or Sr2+ current was larger than the Ca2+ current. Activation was accelerated by increasing the membrane potential. In general, the time course of decay was well fitted by the sum of two exponentials, but consideration of a third (ultra-slow) decay component was also necessary when the current generated by a 2-s command pulse was analyzed. Superimposition of activation and inactivation curves showed the presence of a significant window current. Carbachol suppressed the Ca2+ current only when the pipette contained a low concentration of ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid. These results show that the L-type Ca2+ current is dominant in gallbladder smooth muscle cells and may contribute to excitation-contraction coupling.

Inhibition by Imipramine of the Voltage-Dependent K+ Channel in Rabbit Coronary Arterial Smooth Muscle Cells

2020 ◽  
Vol 178 (2) ◽  
pp. 302-310
Author(s):  
Jin Ryeol An ◽  
Mi Seon Seo ◽  
Hee Seok Jung ◽  
Ryeon Heo ◽  
Minji Kang ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Dependent Manner ◽  
Arterial Smooth Muscle ◽  
Closed State ◽  
Kv Channels ◽  
State Dependent ◽  
Voltage Dependent ◽  
Arterial Smooth Muscle Cells

Abstract Imipramine, a tricyclic antidepressant, is used in the treatment of depressive disorders. However, the effect of imipramine on vascular ion channels is unclear. Therefore, using a patch-clamp technique we examined the effect of imipramine on voltage-dependent K+ (Kv) channels in freshly isolated rabbit coronary arterial smooth muscle cells. Kv channels were inhibited by imipramine in a concentration-dependent manner, with an IC50 value of 5.55 ± 1.24 µM and a Hill coefficient of 0.73 ± 0.1. Application of imipramine shifted the steady-state activation curve in the positive direction, indicating that imipramine-induced inhibition of Kv channels was mediated by influencing the voltage sensors of the channels. The recovery time constants from Kv-channel inactivation were increased in the presence of imipramine. Furthermore, the application of train pulses (of 1 or 2 Hz) progressively augmented the imipramine-induced inhibition of Kv channels, suggesting that the inhibitory effect of imipramine is use (state) dependent. The magnitude of Kv current inhibition by imipramine was similar during the first, second, and third depolarizing pulses. These results indicate that imipramine-induced inhibition of Kv channels mainly occurs in the closed state. The imipramine-mediated inhibition of Kv channels was associated with the Kv1.5 channel, not the Kv2.1 or Kv7 channel. Inhibition of Kv channels by imipramine caused vasoconstriction. From these results, we conclude that imipramine inhibits vascular Kv channels in a concentration- and use (closed-state)-dependent manner by changing their gating properties regardless of its own function.

scholarly journals Calcium Channels and Nifedipine Inhibition of Serotonin-Induced [3H]Thymidine Incorporation in Cultured Cerebral Smooth Muscle Cells

1992 ◽  
Vol 12 (1) ◽  
pp. 139-146 ◽  
Author(s):  
Thomas A. Kent ◽  
Allahyar Jazayeri ◽  
J. Marc Simard
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Thymidine Incorporation ◽  
Membrane Surface ◽  
Muscle Cells ◽  
Thymidine Uptake ◽  
Patch Clamp Technique ◽  
Whole Cell Patch Clamp ◽  
Voltage Dependent ◽  
Alternate Mechanism

Cultures of smooth muscle cells were prepared from the basilar artery of adult guinea pigs. Passaged cultures (10–30 passages) that expressed serotonin receptors were studied using [3H]thymidine incorporation. When tested in quiescent medium, serotonin potently stimulated [3H]thymidine incorporation (EC50 of 31 n M) by as much as 400% at 24 h. The number of cells was not significantly increased at 24 or 48 h. At concentrations of 10−8–10−5 M 5-HT, [3H]thymidine uptake was reduced 40–50% by the dihydropyridine Ca2+ channel blocker, nifedipine (1 μ M). To demonstrate a possible mechanism for the sensitivity to nifedipine, Ca2+ currents were measured using the whole cell patch clamp technique. The cells expressed dihydropyridine-sensitive L-type Ca2+ channels, but not other subtypes of Ca2+ channels, as indicated by the kinetic and voltage-dependent characteristics of the current and by the stimulatory effect of Bay K 8644. The magnitude of the Ca2+ currents was related exponentially to the membrane surface area, measured as cell capacitance. These data support the association of dihydropyridine-sensitive Ca2+ channels with mitogenesis in vascular smooth muscle, and suggest an alternate mechanism of action for the beneficial effect of dihydropyridines in prophylaxis of cerebral vasospasm.

Protriptyline, a tricyclic antidepressant, inhibits voltage-dependent K+ channels in rabbit coronary arterial smooth muscle cells

2020 ◽  
Vol 52 (3) ◽  
pp. 320-327 ◽  
Author(s):  
Jin Ryeol An ◽  
Hojung Kang ◽  
Hongliang Li ◽  
Mi Seon Seo ◽  
Hee Seok Jung ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Steady State ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Tricyclic Antidepressant ◽  
Dependent Manner ◽  
Kv Channels ◽  
State Dependent ◽  
Voltage Dependent ◽  
Arterial Smooth Muscle Cells

Abstract In this study, we explore the inhibitory effects of protriptyline, a tricyclic antidepressant drug, on voltage-dependent K+ (Kv) channels of rabbit coronary arterial smooth muscle cells using a whole-cell patch clamp technique. Protriptyline inhibited the vascular Kv current in a concentration-dependent manner, with an IC50 value of 5.05 ± 0.97 μM and a Hill coefficient of 0.73 ± 0.04. Protriptyline did not affect the steady-state activation kinetics. However, the drug shifted the steady-state inactivation curve to the left, suggesting that protriptyline inhibited the Kv channels by changing their voltage sensitivity. Application of 20 repetitive train pulses (1 or 2 Hz) progressively increased the protriptyline-induced inhibition of the Kv current, suggesting that protriptyline inhibited Kv channels in a use (state)-dependent manner. The extent of Kv current inhibition by protriptyline was similar during the first, second, and third step pulses. These results suggest that protriptyline-induced inhibition of the Kv current mainly occurs principally in the closed state. The increase in the inactivation recovery time constant in the presence of protriptyline also supported use (state)-dependent inhibition of Kv channels by the drug. In the presence of the Kv1.5 inhibitor, protriptyline did not induce further inhibition of the Kv channels. However, pretreatment with a Kv2.1 or Kv7 inhibitor induced further inhibition of Kv current to a similar extent to that observed with protriptyline alone. Thus, we conclude that protriptyline inhibits the vascular Kv channels in a concentration- and use-dependent manner by changing their gating properties. Furthermore, protriptyline-induced inhibition of Kv channels mainly involves the Kv1.5.

Effects of the gap junction blocker glycyrrhetinic acid on gastrointestinal smooth muscle cells

2005 ◽  
Vol 288 (4) ◽  
pp. G832-G841 ◽  
Author(s):  
Yukari Takeda ◽  
Sean M. Ward ◽  
Kenton M. Sanders ◽  
Sang Don Koh
Keyword(s):  
Smooth Muscle ◽  
Patch Clamp ◽  
Smooth Muscle Cells ◽  
Gap Junctions ◽  
Lucifer Yellow ◽  
Muscle Cells ◽  
Glycyrrhetinic Acid ◽  
Delayed Rectifier ◽  
Dependent Manner ◽  
Patch Clamp Technique

In the tunica muscularis of the gastrointestinal (GI) tract, gap junctions form low-resistance pathways between pacemaker cells known as interstitial cells of Cajal (ICCs) and between ICC and smooth muscle cells. Coupling via these junctions facilitates electrical slow-wave propagation and responses of smooth muscle to enteric motor nerves. Glycyrrhetinic acid (GA) has been shown to uncouple gap junctions, but previous studies have shown apparent nonspecific effects of GA in a variety of tissues. We tested the effects of GA using isometric force measurements, intracellular microelectrode recordings, the patch-clamp technique, and the spread of Lucifer yellow within cultured ICC networks. In murine small intestinal muscles, β-GA (10 μM) decreased phasic contractions and depolarized resting membrane potential. Preincubation of GA inhibited the spread of Lucifer yellow, increased input resistance, and decreased cell capacitance in ICC networks, suggesting that GA uncoupled ICCs. In patch-clamp experiments of isolated jejunal myocytes, GA significantly decreased L-type Ca2+ current in a dose-dependent manner without affecting the voltage dependence of this current. The IC50 for Ca2+ currents was 1.9 μM, which is lower than the concentrations used to block gap junctions. GA also significantly increased large-conductance Ca2+-activated K+ currents but decreased net delayed rectifier K+ currents, including 4-aminopyridine and tetraethylammonium-resistant currents. In conclusion, the reduction of phasic contractile activity of GI muscles by GA is likely a consequence of its inhibitory effects on gap junctions and voltage-dependent Ca2+ currents. Membrane depolarization may be a consequence of uncoupling effects of GA on gap junctions between ICCs and smooth muscles and inhibition of K+ conductances in smooth muscle cells.

scholarly journals Endothelium-independent, ouabain-sensitive relaxation of bovine coronary arteries by EETs

2001 ◽  
Vol 280 (3) ◽  
pp. H1113-H1121 ◽  
Author(s):  
Phillip F. Pratt ◽  
Pinlan Li ◽  
Cecilia J. Hillard ◽  
Jason Kurian ◽  
William B. Campbell
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Potassium Chloride ◽  
Coronary Arteries ◽  
Muscle Tone ◽  
Muscle Cells ◽  
Resting Membrane Potential ◽  
Dependent Manner ◽  
Independent Manner ◽  
Concentration Dependent Manner

Endothelium-derived hyperpolarizing factor (EDHF) is released in response to agonists such as ACh and bradykinin and regulates vascular smooth muscle tone. Several studies have indicated that ouabain blocks agonist-induced, endothelium-dependent hyperpolarization of smooth muscle. We have demonstrated that epoxyeicosatrienoic acids (EETs), cytochrome P-450 metabolites of arachidonic acid, function as EDHFs. To further test the hypothesis that EETs represent EDHFs, we have examined the effects of ouabain on the electrical and mechanical effects of 14,15- and 11,12-EET in bovine coronary arteries. These arteries are relaxed in a concentration-dependent manner to 14,15- and 11,12-EET (EC50 = 6 × 10−7 M), bradykinin (EC50 = 1 × 10−9 M), sodium nitroprusside (SNP; EC50 = 2 × 10−7 M), and bimakalim (BMK; EC50 = 1 × 10−7 M). 11,12-EET-induced relaxations were identical in vessels with and without an endothelium. Potassium chloride (1–15 × 10−3 M) inhibited [3H]ouabain binding to smooth muscle cells but failed to relax the arteries. Ouabain (10−5 to 10−4 M) increased basal tone and inhibited the relaxations to bradykinin, 11,12-EET, and 14,15-EET, but not to SNP or BMK. Barium (3 × 10−5 M) did not alter EET-induced relaxations and ouabain plus barium was similar to ouabain alone. Resting membrane potential ( E m) of isolated smooth muscle cells was −50.2 ± 0.5 mV. Ouabain (3 × 10−5 and 1 × 10−4 M) decreased E m(−48.4 ± 0.2 mV), whereas 11,12-EET (10−7 M) increased E m (−59.2 ± 2.2 mV). Ouabain inhibited the 11,12-EET-induced increase in E m. In cell-attached patch clamp studies, 11,12-EET significantly increased the open-state probability ( NP o) of a calcium-activated potassium channel compared with control cells (0.26 ± 0.06 vs. 0.02 ± 0.01). Ouabain did not change NP o but blocked the 14,15-EET-induced increase in NP o. These results indicate that: 1) EETs relax coronary arteries in an endothelium-independent manner, 2) unlike EETs, potassium chloride does not relax the coronary artery, and 3) ouabain inhibits bradykinin- and EET-induced relaxations as has been reported for EDHF. These findings provide further evidence that EETs are EDHFs.

Dual effect of phosphatase inhibitors on calcium channels in intestinal smooth muscle cells

1993 ◽  
Vol 264 (2) ◽  
pp. C296-C301 ◽  
Author(s):  
K. Obara ◽  
H. Yabu
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Patch Clamp Technique ◽  
Pipette Solution ◽  
Phosphatase Inhibitors ◽  
Inward Current ◽  
Whole Cell Patch Clamp ◽  
Voltage Dependent ◽  
High Concentrations

The effects of okadaic acid (OA) and calyculin A (CL-A), potent inhibitors of protein phosphatases type 1 (PP1) and type 2A (PP2A), on inward current carried by Ba2+ through voltage-dependent Ca2+ channel in guinea pig teniae coli smooth muscle cells were investigated using whole-cell patch-clamp technique. High concentrations of OA (5 x 10(-8)-5 x 10(-6) M) and CL-A (10(-9)-10(-7) M) dose dependently increased the inward current. The concentration producing apparent half-maximum enhancing effect values for OA and CL-A were 1.12 x 10(-7) and 1.78 x 10(-9) M, respectively. CL-A appeared to be approximately 100-fold more potent in increasing the inward current than OA. Lower concentrations of OA (10(-10)-2 x 10(-8) M) and CL-A (10(-11)-10(-9) M) decreased the inward current. The maximum inhibitory effects of OA and CL-A were observed at 10(-8) M OA and 5 x 10(-10) M CL-A, respectively. CL-A is approximately 100 times more effective inhibitor of PP1 than OA, and lower concentrations of OA and CL-A used in the present study inhibit PP2A activity, but they have no or little effect on PP1 activity (Ishihara, H., B. L. Martin, D. L. Brautigan, H. Karaki, H. Ozaki, Y. Kato, N. Fusetani, S. Watabe, K. Hashimoto, D. Uemura and D. J. Hartshorne. Biochem. Biophys. Res. Commun. 159: 871-877, 1989). In the absence of ATP in pipette solution, OA and CL-A did not affect the inward current.(ABSTRACT TRUNCATED AT 250 WORDS)

ATP-sensitive potassium channels in cultured arterial segments

1996 ◽  
Vol 271 (6) ◽  
pp. H2462-H2468 ◽  
Author(s):  
T. Kleppisch ◽  
B. Winter ◽  
M. T. Nelson
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Katp Channels ◽  
Muscle Cells ◽  
Mesenteric Arteries ◽  
Force Density ◽  
Dependent Manner ◽  
Growth Responses ◽  
Patch Clamp Technique ◽  
Arterial Smooth Muscle

Organ cultures of arteries have been used to study growth responses, proliferation, and contractility. However, the function of specific-ion channels in cultured arteries has not been investigated. ATP-sensitive K+ (KATP) channels play an important role in the control of arterial tone. The goal of this study was to determine the functional state of KATP channels in arteries kept in culture. Segments from rabbit mesenteric arteries were cultured in for 2-7 days. To explore the properties of KATP channels, the effects of KATP-channel modulators and other vasoactive substances on isometric force, density, and modulation of KATP currents in single smooth muscle cells isolated from cultured vessels were examined. Isometric contractions were measured with a resistance-vessel myograph. Whole cell KATP currents were recorded with the patch-clamp technique. Membrane capacitance and KATP-current density in single smooth muscle cells from freshly dissected (control) and cultured arteries were not altered. At -60 mV, glibenclamide-sensitive currents in the presence of the K(+)-channel opener pinacidil were -4.7 +/- 1.2, -4.7 +/- 0.6, and -4.6 +/- 0.7 pA/pF for control and 2- and 4-day arteries, respectively. Inhibitory modulation of KATP currents in arterial smooth muscle also remained intact for 4 days in culture; the vasoconstrictor histamine (10 microM) reduced glibenclamide-sensitive currents in the presence of pinacidil by 61.2 +/- 2.8, 42.4 +/- 10.1, and 41.2 +/- 6.1% for control and 2- and 4-day arteries, respectively. Pinacidil relaxed control and cultured arteries (1-7 days) in a dose-dependent manner. Half-maximal effective concentrations of pinacidil were 0.42, 0.24, 0.23, and 0.51 microM for control and 2-, 4-, and 7-day arteries, respectively, whereas maximal relaxations to pinacidil were 62.9, 47.5, 37.5, and 55.7% for control and 2-, 5-, and 7-day arteries, respectively. Histamine, norepinephrine, and serotonin constricted cultured arteries, although responses to histamine and norepinephrine diminished by 30-50% after 5 days in culture. The relaxant effect of acetylcholine was not maintained in cultured arteries. Sodium nitroprusside, however, effectively relaxed arteries cultured for 2-7 days. The data indicate that with the culture model described, KATP channels in arterial smooth muscle remained functional and contractile responses in arterial segments were maintained for up to 7 days. These results suggest that this approach can be used to study either long-term regulation of KATP channels or the role of this channel type in growth responses.

Effect of chronic hypoxia on K+ channels: regulation in human pulmonary vascular smooth muscle cells

1997 ◽  
Vol 272 (4) ◽  
pp. C1271-C1278 ◽  
Author(s):  
W. Peng ◽  
J. R. Hoidal ◽  
S. V. Karwande ◽  
I. S. Farrukh
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Chronic Hypoxia ◽  
Muscle Cells ◽  
K Channel ◽  
Resting Membrane Potential ◽  
Delayed Rectifier ◽  
Voltage Dependent ◽  
Dependent Protein ◽  
Pulmonary Arterial

We investigated the effects of chronic hypoxia on the major outward K+ currents in early cultured human main pulmonary arterial smooth muscle cells (HPSMC). Unitary currents were measured from inside-out, outside-out, and cell-attached patches of HPSMC. Chronic hypoxia depolarized resting membrane potential (Em) and reduced the activity of a charybdotoxin (CTX)- and iberiotoxin-sensitive, Ca2+-dependent K+ channel (KCa). The 4-aminopyridine-sensitive and CTX-insensitive channel or the delayed rectifier K+ channel was unaffected by chronic hypoxia. Chronic hypoxia caused a +33- to +53-mV right shift in voltage-dependent activation of K(Ca) and a decrease in K(Ca) activity at all cytosolic Ca2+ concentrations ([Ca2+]i) in the range of 0.1-10 microM. Thus the hypoxia-induced decrease in K(Ca) activity was most likely due to a decrease in K(Ca) sensitivity to Em and [Ca2+]i. Chronic hypoxia reduced the ability of nitric oxide (NO.) and guanosine 3',5'-cyclic monophosphate (cGMP) to activate K(Ca). The cGMP-dependent protein kinase-induced activation of K(Ca) was also significantly inhibited by chronic hypoxia. In addition, inhibiting channel dephosphorylation with calyculin A caused significantly less increase in K(Ca) activity in membrane patches excised from chronically hypoxic HPSMC compared with normoxic controls. This suggests that the mechanism by which hypoxia modulates NO.-induced K(Ca) activation is by decreasing the NO./cGMP-mediated phosphorylation of the channel.

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