Maternal organ distribution of cardiac output in the diet-restricted pregnant rat.

Maternal organ distribution of cardiac output was measured with 15-micron diameter, radioactively labeled microspheres in ad libitum-fed or 50% diet-restricted, term pregnant rats, and in ad libitum-fed nonpregnant rats. The diet-restricted dams had a 33% lower total cardiac output than the ad libitum-fed dams, but it was not significantly different from that of the nonpregnant rats. Placental blood flow in the diet-restricted rats was 30% lower than that in the ad libitum-fed rats. Except for a higher blood flow to the pancreas and a lower blood flow to the uterine tissue, blood flows to the other organs of the diet-restricted dams were not significantly different from those of ad libitum-fed pregnant dams. Blood flows to the lungs, small intestine and ovaries of the diet-restricted pregnant rats were higher than those in the nonpregnant rats. Dietary restriction resulted in a decreased percentage of the cardiac output being distributed to the pregnant uterus and an increased percentage to the hepatic portal circulation, thus maintaining a liver blood flow similar to that in nonpregnant rats. Thus, maternal liver blood flow, rather than that to the placentas, is protected during malnutrition.