Hamada S, Kawarabayashi T, Ikeda M, Sugimori H, Hamasaki Y, Kumamoto T, Tsukamoto T
Department of Obstetrics and Gynecology, Saga Medical School.
Nihon Sanka Fujinka Gakkai Zasshi. 1990 Jun;42(6):605-11.
We investigated the effects of Ritodrine (10(-10)-10(-7) g/ml) on spontaneous contractions of rat myometrium at gestational days 14, 16, 18 and 21. 1. More than 10(-8)g/ml Ritodrine obviously suppressed the spontaneous contractions more than smaller doses. The inhibitory effects of smaller doses on days 14 and 16 were different from those on days 18 and 21, the former being more effective. 2. Smaller doses of Ritodrine (10(-10)-10(-8)g/ml) caused transient excitation, which was inhibited by pretreatment with Phentolamine. 3. Rebound excitation was observed in most of the specimens. 4. Spontaneous contractions reappeared during long-term administration of Ritodrine and the patterns could be classified into three types. These results suggested that the effects of Ritodrine might vary according to the number of pregnant days and that the critical Ritodrine dose for a suppressive effect is 10(-8)g/ml, and there are a transient alpha-excitatory effect, rebound excitation and three types of suppression as a result of long-term administration.
我们研究了利托君（10⁻¹⁰ - 10⁻⁷克/毫升）对妊娠第14、16、18和21天大鼠子宫肌层自发收缩的影响。1. 超过10⁻⁸克/毫升的利托君比小剂量更明显地抑制自发收缩。小剂量在第14天和第16天的抑制作用与第18天和第21天不同，前者更有效。2. 小剂量的利托君（10⁻¹⁰ - 10⁻⁸克/毫升）引起短暂兴奋，酚妥拉明预处理可抑制这种兴奋。3. 在大多数标本中观察到反跳性兴奋。4. 在长期给予利托君期间，自发收缩重新出现，其模式可分为三种类型。这些结果表明，利托君的作用可能因妊娠天数而异，产生抑制作用的临界利托君剂量为10⁻⁸克/毫升，并且存在短暂的α-兴奋作用、反跳性兴奋以及长期给药导致的三种类型的抑制。
