THE BLOOD PRESSURE OF THE FETAL RAT AND ITS RESPONSE TO RENIN AND ANGIOTONIN

Abstract

A technique is described for the study of heart rates and blood pressure in the mother and fetus simultaneously in rats (Rattus norvegicus). Curves are presented to summarize the data at different stages of gestation. Inj. of an effective dose of renin into the blood-stream of rats in late pregnancy does not affect the fetal blood pressure. Inj. of even larger doses of renin, angiotonin and adrenaline into the maternal blood-stream causes a profound fall in fetal blood pressure. Recovery is slow and incomplete. Injs. of renin, angiotonin and adrenaline into the fetal blood-stream cause a pronounced rise in fetal blood pressure. With renin, tachyphylaxis was demonstrated in both mother and fetus independently but was not transferred from one to the other. Injs. of renin and angiotonin large enough to raise the maternal blood pressure, when injected directly into the maternal circulation, fail to do so if injected into the fetal circulation. The fetus is very much less responsive to renin, angiotonin and epinephrine than the mother.