[Effects of vesnarinone on L-type single Ca2+ channel current in cultured ventricular myocytes of embryonic chick].
The effects of vesnarinone on L-type Ca2+ channel current of embryonic chick ventricular myocytes were studied with cell-attached patch clamp technique. Vesnarinone was used in the concentrations of 10(-5), 2 x 10(-5) and 10(-4) mol/L; the availability (P8) of Ca2+ channel activity was increased (P < 0.001) markedly (about 2-3 fold). The increasing of the open probability (Po) of Ca2+ channel by vesnarinone showed concentration-dependence. The increase was 2.25 (10(-5)mol/L), 3(2 x 10(-5)mol/L) and 4.3(10(-4)mol/L) fold. The open time rate constant (tau 0) and close time rate constant (tau 1 and tau 2) of Ca2+ channel were not changed in the concentrations of 10(-5) and 2 x 10(-5) mol/L, but the tau 0 was slightly decreased in the concentration of 10(-4) mol/L. The actions of vesnarinone on single Ca2+ current were compared with those of milrinone (it is known as an PDE inhibitor which had inotropic effect associated with an increase in cytoplasmic cAMP level.) The effects of milrinone on P8, tau 0 and tau 1 were similar with those of vesnarinone (10(-4) mol/L), but the increase of Po was 2 fold less than that of vesnarinone. The results showed that apart from the role of PDE inhibitor, vesnarinone has other effects on myocytes.
Zhang
Y
Y
Department of Physiology, Luzhou Medical College.
Li
H
H
Lan
T
T
Zeng
X
X
D000818:Animals; D015220:Calcium Channels / Q000187:drug effects*; D002316:Cardiotonic Agents / Q000494:pharmacology*; D002478:Cells, Cultured; D002642:Chick Embryo; D020105:Milrinone; D009206:Myocardium / Q000166:cytology*; D018408:Patch-Clamp Techniques; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D011719:Pyrazines; D011728:Pyridones / Q000494:pharmacology; D011804:Quinolines / Q000494:pharmacology*
D015220:Calcium Channels; D002316:Cardiotonic Agents; D010726:Phosphodiesterase Inhibitors; D011719:Pyrazines; D011728:Pyridones; D011804:Quinolines; C041667:vesnarinone; D020105:Milrinone