Effect of cocaine on the time course of calcium contracture of isolated smooth muscle cells of guinea pig vas deferens

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.

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Depolarization-mediated intracellular calcium transients in isolated smooth muscle cells of guinea-pig urinary bladder.

The Journal of Physiology ◽

10.1113/jphysiol.1991.sp018505 ◽

1991 ◽

Vol 435 (1) ◽

pp. 187-205 ◽

Cited By ~ 66

Author(s):

Y a Ganitkevich V ◽

G Isenberg

Keyword(s):

Smooth Muscle ◽

Urinary Bladder ◽

Guinea Pig ◽

Smooth Muscle Cells ◽

Intracellular Calcium ◽

Muscle Cells ◽

Calcium Transients ◽

Isolated Smooth Muscle Cells

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Effects of nicorandil on isolated smooth muscle cells from guinea-pig taenia caeci

Comparative Biochemistry and Physiology Part C Comparative Pharmacology ◽

10.1016/0742-8413(88)90143-0 ◽

1988 ◽

Vol 89 (1) ◽

pp. 45-52

Author(s):

Yasushi Ito ◽

Kazuo Obara

Keyword(s):

Smooth Muscle ◽

Guinea Pig ◽

Smooth Muscle Cells ◽

Muscle Cells ◽

Isolated Smooth Muscle Cells

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The Effect of Intracellular Current Pulses in Smooth Muscle Cells of the Guinea Pig Vas Deferens at Rest and during Transmission

The Journal of General Physiology ◽

10.1085/jgp.50.10.2459 ◽

1967 ◽

Vol 50 (10) ◽

pp. 2459-2475 ◽

Cited By ~ 36

Author(s):

M. R. Bennett

Keyword(s):

Smooth Muscle ◽

Guinea Pig ◽

Action Potential ◽

Smooth Muscle Cells ◽

Vas Deferens ◽

Electrical Coupling ◽

Muscle Cells ◽

Active Response ◽

Current Pulses ◽

Passive Response

The effect of intracellular current pulses on the membrane of smooth muscle cells of the guinea pig vas deferens at rest and during transmission was studied. Two main response types were identified: active response cells, in which a spike was initiated in response to depolarizing currents of sufficient strength and duration; passive response cells, in which depolarizing currents gave only electrotonic potential changes. These cells were three times more numerous than the active response cells. During the crest of the active response the input resistance fell by about 25% of the resting value. Comparison of the active response with the action potential due to stimulating the hypogastric nerve showed that the former was smaller in amplitude and had a slower rate of rise and higher threshold. Electrical coupling occurred between the smooth muscle cells during the propagation of the action potential. Depolarizing current pulses had no effect on the amplitude of the excitatory junction potential (E.J.P.) in passive response cells, but in general did decrease its amplitude in active response cells. These results are discussed with respect to the mechanism of autonomic neuroeffector transmission.

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