[Effect of nitrendipine on isolated uterus and other smooth muscles of the rat].
Increasing concentrations of nitrendipine were found to inhibit various types of muscular activation (electrical stimulation, acetylcholine, oxytocin, potassium chloride), as well as the spontaneous rhythmic activity of the isolated rat uterus. The degree of the inhibitory effect of nitrendipine depends on the type of activation. Nitrendipine showed an exceptionally high efficacy in inhibiting contractions induced by electrical stimulation and of spontaneous rhythmic activity. For inhibition of these contractions even osmolar concentrations of nitrendipine were sufficient. The relaxant effect of nitrendipine depended on the concentration of extracellular calcium and the time of incubation of nitrendipine in the bathing medium. Nitrendipine showed high selectivity for the uterine smooth muscle because in a very high concentrations is exerted an insignificant relaxation of the other isolated smooth muscles (oesophagus, urinary bladder). Our experiments indicate that nitrendipine might have a role in therapy of premature delivery and abortion because of its great selectivity for the uterine smooth muscle. Addition of calcium into the medium restores completely all types of muscular activation after the inhibitory action of nitrendipine except its depressive action on the phasic component of oxytocin-induced contractions. These findings that individual types of activation, after inhibitory action of nitrendipine, are reestablished in various degrees by the addition of calcium into the medium, are also an additional confirmation about the existence of various types of calcium channels.
Milovanović
S
S
Institut technique militaire, Belgrade.
Prostran
M
M
Varagić
V
V
Bosković
B
B
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D004558:Electric Stimulation; D005260:Female; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D009568:Nitrendipine / Q000494:pharmacology*; D010121:Oxytocin / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D014590:Uterine Contraction / Q000187:drug effects*; D014599:Uterus / Q000187:drug effects / Q000502:physiology*
D010121:Oxytocin; D011189:Potassium Chloride; D009568:Nitrendipine; D000109:Acetylcholine; D002118:Calcium
Effet de la nitrendipine sur l'utérus isolé et autres muscles lisses du rat.