MICRO-VASCULAR AND CLINICAL EFFECTS OF ALTERED PERITONEAL-DIALYSIS SOLUTIONS

Blood flow in the peritoneum is important in efficient peritoneal dialysis. No previous studies have related alterations and control of the peritoneal microcirculation to dialysis efficiency. Closed-circuit television microscopy was used to quantitate in vivo response (changes in vessel diameter) to dialysis solutions of the small arteries on the mesothelial surface of the rat cecum and arterioles of the rat cremaster muscle. These responses were correlated with solute clearances from multiple peritoneal dialysis performed in humans. In the cremaster, a transient vasconstriction was followed by a prolonged vasodilation. pH adjustments of the dialysis solution from 5.6 to 7.4 had no effect on the microvascular response and no effect on solute clearances during human peritoneal dialysis. In the cecum, dialysis solution caused a prolonged dilation which reached a maximum in about 10 min. Since dilation appears to be an important determinant of solute clearances during human peritoneal dialysis, the effects of a vasodilator, sodium nitroprusside, were determined. Sodium nitroprusside decreased the time to maximal dilation, which correlated clinically with an increased solute clearance during exchanges with this drug. Since nitroprusside increased clearances of the larger MW solutes proportionally more than of smaller MW solutes, nitroprusside apparently increases solute clearances by both a vasodilatory effect and by an effect on vascular membrane permeability and area for solute exchange.