Effect of DOCA-NaCl hypertension on pre- and postcapillary resistance in isolated hindlimbs of dogs

Abstract

Measurements of precapillary resistance (Ra), postcapillary resistance (Ra), postcapillary resistance (Rv), capillary filtration coefficient (Kf), and mean capillary hydrostatic pressure (Pci) were made during constant-flow perfusion of isolated hindlimbs from control and deoxycorticosterone acetate (DOCA)-NaCl-treated hypertensive dogs by the isogravimetric method. Both Ra and Rv were found to be significantly increased in the hypertensive group, even after maximal vasodilatation with papaverine. The net decreases in Ra and Rv following papaverine infusion were not significantly different between control and hypertensive animals. These results suggest that the observed increases in Ra and Rv were due to structural adaptation (increased wall-to-lumen ratio). Nonpapaverinized hindlimbs from hypertensive dogs exhibited a significant 40% reduction in Kf, suggesting that capillary surface area for fluid exchange was decreased. The compliance of the hindlimb vascular bed was found to be significantly decreased in the hypertensive group. Pci of both groups of hindlimbs were not different between groups and was not affected by papaverine. This result suggests that net capillary permeability to plasma proteins in this preparation was not changed by hypertension.