Inhibitory Effects of Isradipine on Spontaneous and Oxytocin- and Carbachol-Stimulated Contractions of Rat Myometrium

Abstract

Our aim was to investigate the effect of isradipine, a second-generation calcium channel blocker, on spontaneous and oxytocin- and carbachol-stimulated contractions of myometrium isolated from nonpregnant and pregnant rats. Amplitude, frequency, duration and integrated area of spontaneous and oxytocin- and carbachol-stimulated contractions of nonpregnant and pregnant rat myometrium were compared before and after the treatment with isradipine (10^–6 to 10^–4 mol/l). Isradipine inhibited contractions of myometrial strips isolated from nonpregnant and pregnant rats in a concentration-dependent manner, with a significant effect on the amplitude (10^–5 to 10^–4 mol/l) and integrated area (3 × 10^–6 to 10^–4 mol/l) of spontaneous and oxytocin- and carbachol-stimulated contractions. Isradipine induced similar concentration-dependent effects on the frequency and duration of spontaneous and carbachol-stimulated contractions at higher concentrations (3 × 10^–5 to 10^–4 mol/l) but had no effect on frequency and duration of oxytocin-stimulated contractions. Isradipine appears to be an effective relaxant in rat myometrium. This effect of isradipine may become therapeutically advantageous in clinical application for preterm labor.

Effect of magnesium sulfate, isradipine, and ritodrine on contractions of myometrium: pregnant human and rat

“…By inhibiting contraction coupling, dihydropyridines decrease the frequency and intensity of myometrial activity (20). Our results agree with previous studies (19, 21, 22) where isradipine has been shown to inhibit myometrial activity of rat uterus by decreasing the frequency and amplitude of contractions. The results obtained from the pregnant human uterus were quantitatively quite similar with those from the rat uterus.…”

“…Calcium channel blockers are a diverse group of organic compounds, which inhibit the influx of extracellular calcium ions across the cell membrane during the slow inward calcium current of the action potential (5, 18). Members of the dihydropyridine class, which include nifedipine, isradipine, and nicardipine, share similar properties and act mainly on l ‐type voltage‐dependent channels where inhibition of the influx of extracellular calcium ions results in myometrial relaxation (8, 19). By inhibiting contraction coupling, dihydropyridines decrease the frequency and intensity of myometrial activity (20).…”

Interactive effect of sevoflurane with isradipine or indomethacin on spontaneous contractile activity of isolated pregnant rat myometrium

“…Myometrial strips were prepared as described. 3,6,14 The myometrial strips were mounted in tissue baths containing Krebs solution, for recording of isometric tension. Preliminary time control experiments with no drug additions showed that strips exhibit stable uterine activity for at least 4 h after preparation.…”

“…4,5 It has been previously shown that isradipine decreased the amplitude and frequency of myometrial contractions in both non-pregnant and pregnant rats in a concentration-dependent manner. 6 Non-steroidal anti-inflammatory drugs (NSAIDs) are potent tocolytic agents that prolong pregnancy for more than seven days. 7,8 Indomethacin, a non-selective cyclooxygenase (COX) inhibitor, is used to prevent preterm delivery.…”

Kronik Sigara ve Alkol Maruziyetinin Gebe Rat Miyometriyum Oksitosin- ve Diltiazem- Aracılı Fonksiyonel Yanıtları Üzerine Etkileri

“…As previously described, the rats were killed by a cervical subluxation at 19th or 21th day of gestation. 18,19 Myometrial strips (approximately 8mm x 2mm x 2mm) were isolated from the middle of uterine horns in the longitudinal direction. The strips were immediately placed and mounted in the organ chambers for isometric tension measurement in modified Kreb's buffer (NaCl 125 mM, KCl 2.4 mM, CaCl2 1.8 mM, MgCl2 0.5 mM, NaHCO3 23.9 mM, and glucose 11 mM) aerated with a gas mixture of 95% O2 and 5% CO2 (pH = 7.4).…”