Milovanović S R, Ognjanović J, Varagić V M, Bosković B
Military Technical Institute, Katanicéva, Belgrade, Yugoslavia.
Arch Int Pharmacodyn Ther. 1988 Sep-Oct;295:291-304.
Increasing concentrations of nicardipine 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 nicardipine depends on the type of activation. Nicardipine showed an exceptionally high efficacy in inhibiting contractions induced by electrical stimulation and of spontaneous rhythmic activity. For inhibition of these contractions, even femtomolar concentrations of nicardipine were sufficient. The relaxant effect of nicardipine depends on the concentration of extracellular calcium and the temperature of the medium. Nicardipine shows high selectivity for the uterine smooth muscle because even in very high concentrations it exerts an insignificant relaxation of the other isolated smooth muscles (oesophagus, bladder, colon descendens) as well as of the isolated intercostal muscle of the rat. Our experiments indicate that nicardipine might have a role in the therapy of premature delivery and abortion because of its great selectivity for the uterine smooth muscle. Nicardipine causes a stronger inhibition of the tonic than of the phasic component of contraction induced by potassium chloride and oxytocin. These findings suggest that potassium chloride and oxytocin act through various populations of calcium channels.
研究发现，随着尼卡地平浓度的增加，它能抑制多种类型的肌肉激活（电刺激、乙酰胆碱、催产素、氯化钾）以及离体大鼠子宫的自发节律性活动。尼卡地平的抑制作用程度取决于激活类型。尼卡地平在抑制电刺激诱导的收缩和自发节律性活动方面表现出极高的效力。对于抑制这些收缩，即使是飞摩尔浓度的尼卡地平也足够了。尼卡地平的松弛作用取决于细胞外钙的浓度和培养基的温度。尼卡地平对子宫平滑肌具有高度选择性，因为即使在非常高的浓度下，它对其他离体平滑肌（食管、膀胱、降结肠）以及大鼠离体肋间肌的松弛作用也不明显。我们的实验表明，由于尼卡地平对子宫平滑肌具有高度选择性，它可能在早产和流产的治疗中发挥作用。尼卡地平对氯化钾和催产素诱导的收缩的强直成分的抑制作用比对相性成分的抑制作用更强。这些发现表明，氯化钾和催产素通过不同群体的钙通道发挥作用。
