INHIBITORY EFFECTS OF ISRADIPINE ON SPONTANEOUS AND OXYTOCIN-STIMULATED AND CARBACHOL-STIMULATED CONTRACTIONS OF RAT MYOMETRIUM

Our aim was to investigate the effect of isradipine, a second-generati on calcium channel blocker, on spontaneous and oxytocin- and carbachol -stimulated contractions of myometrium isolated from nonpregnant and p regnant rats. Amplitude, frequency, duration and integrated area of sp ontaneous and oxytocin- and carbachol-stimulated contractions of nonpr egnant and pregnant rat myometrium were compared before and after the treatment with isradipine (10(-6) to 10(-4) mol/l). Isradipine inhibit ed contractions of myometrial strips isolated from nonpregnant and pre gnant rats in a concentration-dependent manner, with a significant eff ect on the amplitude (10(-5) to 10-4 mol/l) and integrated area (3 x 1 0(-6) to 10(-4) mol/1) of spontaneous and oxytocin- and carbachol-stim ulated contractions. Isradipine induced similar concentration-dependen t effects on the frequency and duration of spontaneous and carbachol-s timulated contractions at higher concentrations (3 x 10(-5) to 10(-4) mol/1) but had no effect on frequency and duration of oxytocin-stimula ted contractions. Isradipine appears to be an effective relaxant in ra t myometrium. This effect of isradipine may become therapeutically adv antageous in clinical application for preterm labor.