Experimental observations on peritoneal transport in rabbits.

Peritoneal transfer kinetics of substances differing in molecular size and lipophilic properties were studied in anuric adult rabbits with ligated ureters. In conscious animals, the dialysate/plasma concentration ratios of creatinine (Cr) and inulin (In) rose exponentially up to 200 min of dwelling. Peritoneal CIn was 0.24 ml/min/kg, and CCr was 0.10 ml/min/kg of body wt. The transfer rate for dipropyl acetic acid (VPA) was higher than for its more lipophilic analogue dibutyl acetic acid (DBA); the apparent equilibrium of the dialysate/plasma concentration ratio for VPA was 0.3 to 0.6 and 0.15 to 0.20 for DBA. Correspondingly, the peritoneal CVPA was higher (0.08 to 0.16 ml/min/kg) than CDBA (0.04 to 0.05 ml/min/kg); peritoneal clearances were 8% vs. 1.5% of the plasma clearances. The addition of nitroglycerin, dopamine, isoprenalin, fenoterol, and nitroprusside sodium to the dialysate did not increase significantly the peritoneal CCr and CIn during 30-min cycles. In conclusion, the peritoneal transport kinetics of creatinine, inulin, and protein are qualitatively similar to clinical data, but of different magnitude. The efficiency of peritoneal dialysis depends on the lipophilic characteristics of the substance to be transferred. The vasoactive drugs studied seem not to be promising for increasing the efficiency of peritoneal transport.