Regional circulatory responses to intestinal work in developing swine

Circulatory effects of intraduodenal feeding with 2 and 5% glucose were studied in 29 fasted swine (1 day to 1 mo old) anesthetized with pentobarbital. Recordings included aortic and intestinal venous pressures and intestinal, renal, and femoral blood flows. Calculations included vascular resistances, arterial and intestinal venous O2 contents, and intestinal O2 consumption. Observations were made before and at 15 and 30 min after a feeding and at end of experiments. Blood flow autoregulation was evaluated before and after feedings. Glucose induced increases in intestinal O2 consumption and blood flow at all ages, but intestinal blood flow autoregulation was enhanced only in 2 wk olds. Blood flow was redistributed to the working gut from the hindlimb, but not the kidney, at all ages. Renal blood flow autoregulation was sustained in 2-wk-old and 1-mo-old animals and became significant in 1 wk olds during intestinal hyperemia. We concluded that basic mechanisms governing blood flow redistribution from hindlimb to working gut are available at birth in swine and that maintenance of renal blood flow depends only partly on autoregulatory capability.