Effect of long-term administration of beta 2-sympathomimetic drug in the diet-restricted pregnant rat model.

To assess whether the maternal-fetal balance could be altered in favor of the fetus during malnutrition by increasing uteroplacental blood flow, 0.5 mg of hexoprenaline per day was added to the diet of one group of diet-restricted rats, while another group served as controls. The radionuclide-labeled microsphere method was used to determine blood flow to the maternal placentas and other organs. Maternal carcass weight but not fetal or placental weights were increased in the hexoprenaline-fed rats. Blood flow to the ileum, jejunum, hepatic artery, kidneys, and placentas was significantly greater in the hexoprenaline group compared with those rats fed the restricted diet alone. Although the placental blood flow was increased in the hexoprenaline-fed rats, the supply of nutrients remained restricted, and in the mother the inherent maternal-fetal balance was maintained by an increase in the blood flow to the liver and small intestine.