Splanchnic circulatory changes during development of renal hypertension.

Total and regional splanchnic blood flows were measured with radiolabeled microspheres (15 micron) in one-kidney, one-clip renal hypertensive rats at 2, 4, and 6 wk after induction of hypertension. Arterial pressures (mean +/- SE, mmHg) for the normotensive rats (N) and age-matched hypertensive rats (H) were 110 +/- 5 and 114 +/- 6 at 2 wk, 104 +/- 4 and 148 +/- 13 at 4 wk, and 117 +/- 6 and 164 +/- 11 at 6 wk, respectively. Total splanchnic blood flow was increased in H compared with N at 4 wk but not at 2 or 6 wk. The blood flow changes among individual splanchnic organs varied in N and H. For example, at 2 and 4 wk, stomach, small intestine, large intestine, pancreas, hepatic artery, and portal venous blood flows in H were unchanged compared with N. At 6 wk, small intestinal and hepatic arterial blood flows were increased in H compared with N, and pancreatic blood flow was decreased. Vascular resistance was not different for any splanchnic organs between N and H at 2 wk, but it was elevated in H for all organs at 4 and 6 wk except for the hepatic artery. In another group of rats, the renal and superior mesenteric arteries (SMA) were instrumented with ultrasonic Doppler flow probes. Acute one-kidney, one-clip hypertension was produced by removing one kidney and mechanically reducing flow to the remaining kidney with a pneumatic occluder. After 2 h of stenosis, mean arterial pressure and SMA flow velocity was decreased by 6%.(ABSTRACT TRUNCATED AT 250 WORDS)