Effects of Intraperitoneal Captopril on Peritoneal Transport in Rats

We studied the effects of various doses of intraperitoneal (I.P.) captopril, (an angiotensin-converting enzyme inhibitor) during peritoneal dialysis, on urea dialysate/plasma (DIP) ratios, dialysate protein (Dpo), dialysate glucose (DG), and drainage volume (VD) in 19 Sprague-Dawley male rats with normal renal function. Similarly, these parameters were measured in five control rats.

Among the study group, 14 rats received 20 to 100 mg/kg of intraperitoneal captopril without effect. Following a larger intraperitoneal dose (75 mg/exchange (ex)) five rats had delayed increases in urea D/P ratios and dialysate protein losses by 30% (p < 0.05) and by 286% (p < 0.025), respectively. During and following intraperitoneal captopril the rats showed enhanced glucose absorption and consequently significant decreases in dialysate glucose concentration. The rats receiving IP captopril, 75 mg/ex remained hypotensive throughout the drug exchanges and three subsequent exchanges.

Increases in dialysate protein concentration and decreases in the dialysate glucose concentration seen with captopril (75 mg/ex) returned to near baseline values only after four to five hours of drug-free exchanges.

These changes, despite systemic hypotension, may reflect an increase in blood flow, capillary permeability and/or surface area subsequent to blockade of the renin-angiotensin system, suggesting some angiotensin II modulation of the peritoneal microcirculation and solute transport during peritoneal dialysis.