Intestinal hemodynamics in dogs with chronic one-kidney, one-wrapped hypertension

Abstract

In pentobarbital-anesthetized dogs with chronic one-kidney, one-wrapped perinephritic hypertension, the status of blood flow and resistance differs among vascular beds. There is normal blood flow with elevated resistance in the limb and elevated blood flow with normal resistance in the ileum. In the present study we investigated the mechanism of elevated flow and normal resistance in the ileum by measuring blood flow, pressure, O2 consumption, reactive hyperemia, pressure-flow relationships, resistance at maximal vasodilation, and nonentrapment (shunting) of 9-microns microspheres in vascularly isolated, blood-perfused ilea of 11 24-h fasted dogs with chronic (greater than 4 wk duration) one-kidney perinephritic hypertension [1KH; PA = 163 +/- 8 (SD) mmHg] and 15 fasted normotensive one-kidney, sham-wrapped dogs (1KC; PA = 108 +/- 7 mmHg). In 1KH ileal blood flow was elevated by 35% (P less than 0.001), but ileal vascular resistance was unchanged. Pressure-flow relationships were similar in hypertensive and normotensive ilea, with little evidence for significant autoregulation in either. We also noted no significant differences in ileal O2 consumption, reactive hyperemia, or resistance at maximal vasodilation. However, we found nonentrapment of microspheres to be a positive function of perfusion pressure (P less than 0.02) and to be increased by 40% during ileal perfusion at levels of perfusion pressure within the hypertensive range (150-200 mmHg). Thus the increased ileal blood flow in 1KH may reflect the effects of a poorly autoregulating tissue, as well as "shunt" flow through pressure-activated channels.(ABSTRACT TRUNCATED AT 250 WORDS)