[beta 1, beta 2-effects of ritodrine in pregnant animal experiments (author's transl)]

beta 2-Stimulant are at present the most effective tocolytic agents. The purpose of this paper is to outline the beta 1-, beta 2-effects of ritodrine in animal experiments. 1) In the pregnant rat uterus at term, ritodrine and terbutaline showed the potent effect. The c-GMP level in the bath medium was significantly decreased by the administration of ritodrine, while the c-AMP levels was significantly increased. 2) When the changes in the maternal serum c-AMP and c-GMP levels after the administration of ritodrine were examined, these results coincided with those obtained experiments in vitro. But decreased in c-AMP and c-GMP levels by administering beta-blocker. The c-AMP and c-GMP levels of placenta, liver, uterus and fetus showed similar patterns, especially c-AMP in the uterine and fetal tissues increased when ritodrine was administered. 3) The administration of ritodrine and terbutaline at the last trimester of pregnancy led to the increased, showing dose-response relationship, in the heart rate of mother and fetus in rabbits. 4) The effect of ritodrine on fetal and neonatal serum glucose concentrations was examined in rats. Sustained hypoglycemia was observed in fetus and neonate delivered within 18 hours of the termination of administration (ritodrine, 10-20 mg, sc).