scholarly journals Inactivation of the voltage-dependent Ca2+ channel current in smooth muscle cells isolated from the guinea-pig detrusor.

1993 ◽  
Vol 471 (1) ◽  
pp. 107-127 ◽  
Author(s):  
S Nakayama ◽  
A F Brading
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Channel Current ◽  
Voltage Dependent

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.

scholarly journals Calcium channel current of vascular smooth muscle cells: extracellular protons modulate gating and single channel conductance.

1994 ◽  
Vol 103 (4) ◽  
pp. 665-678 ◽  
Author(s):  
U Klöckner ◽  
G Isenberg
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Single Channel ◽  
Muscle Cells ◽  
Surface Charges ◽  
Channel Conductance ◽  
Channel Current ◽  
Voltage Dependent

Modulation of L-type Ca2+ channel current by extracellular pH (pHo) was studied in vascular smooth muscle cells from bovine pial and porcine coronary arteries. Relative to pH 7.4, alkaline pH reversibly increased and acidic pH reduced ICa. The efficacy of pHo in modulating ICa was reduced when the concentration of the charge carrier was elevated ([Ca2+]o or [Ba2+]o varied between 2 and 110 mM). Analysis of whole cell and single Ca2+ channel currents suggested that more acidic pHo values shift the voltage-dependent gating (approximately 15 mV per pH-unit) and reduce the single Ca2+ channel conductance gCa due to screening of negative surface charges. pHo effects on gCa depended on the pipette [Ba2+] ([Ba2+]p), pK*, the pH providing 50% of saturating conductance, increased with [Ba2+]p according to pK* = 2.7-2.log ([Ba2+]p) suggesting that protons and Ba2+ ions complete for a binding site that modulates gCa. The above mechanisms are discussed in respect to their importance for Ca2+ influx and vasotonus.

ω-3 Polyunsaturated fatty acids—modulation of voltage-dependent L-type Ca2+ current in guinea-pig tracheal smooth muscle cells

1998 ◽  
Vol 355 (2-3) ◽  
pp. 257-266 ◽  
Author(s):  
Hisanori Hazama ◽  
Toshiaki Nakajima ◽  
Michiko Asano ◽  
Kuniaki Iwasawa ◽  
Toshihiro Morita ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Smooth Muscle ◽  
Guinea Pig ◽  
Polyunsaturated Fatty Acids ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Tracheal Smooth Muscle ◽  
Voltage Dependent
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