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Effect of Ritodrine Hydrochloride on Uterine Activity and Maternal and Fetal Circulations in the Pregnant Sheep
Author(s) -
Fujimoto Seiichiro,
Akahane Masuo,
Uzuki Katsuya,
Inagawa Akira,
Sakai Keiichiro,
Ichinoe Kihyoe
Publication year - 1983
Publication title -
asia‐oceania journal of obstetrics and gynaecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.597
H-Index - 50
eISSN - 1447-0756
pISSN - 0389-2328
DOI - 10.1111/j.1447-0756.1983.tb00640.x
Subject(s) - ritodrine , propranolol , oxytocin , uterine contraction , heart rate , fetus , medicine , endocrinology , tachycardia , blood pressure , uterus , pregnancy , biology , gestation , genetics
The effects of ritodrine hydrochloride on uterine activity and maternal and fetal circulations were investigated in chronically prepared pregnant sheep. Ritodrine inhibited oxytocin‐induced uterine contractions in a dose‐dependent manner. The inhibition of uterine activity at 3 mcg/kg/min of ritodrine was about 70%, and greater infusion rates resulted in only minimal further inhibition of the uterine activity. Maternal tachycardia but no hypotension were observed during ritodrine infusion. There were no significant changes in fetal heart rate or blood pressure. Uterine arterial blood flow decreased remarkably at higher doses of ritodrine. These changes were, however, less pronounced when ritodrine was infused at a constant dose of 3 mcg/kg/min, which was sufficient to inhibit the uterine activity. In addition, propranolol blocked the effect of ritodrine on uterine activity and maternal heart rate. This supports the view that ritodrine produces its effects through activation of adrenergic β ‐receptor.