Yarar Y, Cetin A, Kaya T
Department of Obstetrics and Gynecology, Cumhuriyet University School of Medicine, 58140 Sivas, Turkey.
J Soc Gynecol Investig. 2001 Jul-Aug;8(4):206-9. doi: 10.1016/s1071-5576(01)00113-7.
We compared in vitro relaxant effect of chloride channel modulators, such as 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) and anthracene-9-carboxylate (9-AC), and beta(2)-adrenergic agonists, such as ritodrine, in pregnant rat myometrium.
Isolated myometrial strips were obtained from eight pregnant rats, and the strips were mounted in organ baths for recording isometric tension. The effects of 10(-8)-10(-4) M ritodrine, 10(-6)-3 x 10(-4) M NPPB, and 10(-6)-10(-3) M 9-AC on spontaneous contractions were recorded.
Ritodrine (10(-8)-10(-5) M) completely inhibited the amplitude and frequency of spontaneous contractions in myometrial strips isolated from pregnant rats in a concentration-dependent manner, but the relaxant effect of ritodrine at 10(-4) M concentration resulted in tachyphylaxis. The chloride channel blocker NPPB (10(-6)-3 x 10(-4) M) and the chloride transport inhibitor 9-AC (10(-5)-10(-3) M) decreased the amplitude of spontaneous myometrial contractions in a concentration-dependent manner; the maximum inhibition produced by the highest tested concentration of each drug was 43.8% and 42.1% of the original degree of spontaneous contractions, respectively. The frequency of myometrial contractions was significantly inhibited by NPPB and 9-AC beginning with the concentration of 10(-4) M.
NPPB and 9-AC appear to be effective relaxants of pregnant rat myometrium. These effects of NPPB and 9-AC might be therapeutically advantageous in clinical management of preterm labor.
我们比较了氯通道调节剂，如5-硝基-2-(3-苯丙基氨基)苯甲酸（NPPB）和蒽-9-羧酸（9-AC），以及β₂肾上腺素能激动剂，如利托君，对妊娠大鼠子宫肌层的体外松弛作用。
从8只妊娠大鼠获取离体子宫肌条，并将肌条安装在器官浴槽中记录等长张力。记录10⁻⁸ - 10⁻⁴ M利托君、10⁻⁶ - 3×10⁻⁴ M NPPB和10⁻⁶ - 10⁻³ M 9-AC对自发收缩的影响。
利托君（10⁻⁸ - 10⁻⁵ M）以浓度依赖性方式完全抑制妊娠大鼠离体子宫肌条自发收缩的幅度和频率，但10⁻⁴ M浓度的利托君松弛作用出现快速耐受。氯通道阻滞剂NPPB（10⁻⁶ - 3×10⁻⁴ M）和氯转运抑制剂9-AC（10⁻⁵ - 10⁻³ M）以浓度依赖性方式降低子宫肌层自发收缩的幅度；每种药物最高测试浓度产生的最大抑制分别为原始自发收缩程度的43.8%和42.1%。从10⁻⁴ M浓度开始，NPPB和9-AC显著抑制子宫肌层收缩频率。
NPPB和9-AC似乎是妊娠大鼠子宫肌层有效的松弛剂。NPPB和9-AC的这些作用在早产的临床管理中可能具有治疗优势。
