Effect of ritodrine on the maternal and fetal endocrine pancreas of the rat.

Pregnant Wistar rats received four high-dose intramuscular injections of ritodrine per day during the last 6 days of pregnancy. The injections provoked an immediate but transient increase in plasma insulin level, without affecting the plasma glucose concentration. At the end of the treatment, the morphology of the endocrine pancreas and the ultrastructure of the B cells of the ritodrine-treated mothers were similar to those of the control mothers. No lasting influence of the treatment was seen in the fetuses of these rats: body weights, blood glucose and insulin levels, morphology of the endocrine pancreas and ultrastructure of the B cells were all normal.