REVIEWS AND ORIGINAL ARTICLES PERITONEAL FLUID AND TRACER ALBUMIN KINETICS IN THE RAT. EFFECTS OF INCREASES IN INTRAPERITONEAL HYDROSTATIC PRESSURE

.Objectives: To study the peritoneal fluid loss rate, the clearance (CI) of radioactive tracer albumin (RISA) eliminated from the peritoneal cavity (PC), as well as the peritoneal-to-plasma RISA clearance (CI-+ P) during acute peritoneal dialysis (PD) at large elevations in intraperitoneal hydrostatic pressure (IPP)..Design: Experimental study in anesthetized Wistar rats..Methods: The intraperitoneal volume (IPV) was assessed using RISA dilution, correcting for the RISA CI from the PC. Volume recovery at termination of the dwells was obtained using graduated cylinders and preweighed gauze tissues. Measurements of CI and CI-+ P were obtained by repeated micro-sampling of dialysate and plasma, respectively. The IPP was continuously measured, and could be varied by external concentric abdominal compression using an inflatable cuff. On termination of the experiments, samples from tissues lining the PC were analyzed with respect to their content of RISA and edema, the latter being assessed from wet/dry weight ratios..Results: At 2 mm Hg of IPP (control) the RISA CI was 27.1:1:2.0(:1:SE)μL.min-l,whereas CI→ Pwasonly 8.07:1:0.67 μL.min-l, at a total fluid loss rate of 10.1:1:5.4μL.min-1 for 1.36 % Dianeal. At an IPP of 14 mm Hg, the CI increased to 55.3±4.1 μL.min-1 and the peritoneal fluid absorption rate was 34.4±5.6 μL.min-l, whereas CI-+ P was just moderately increased as compared to control (11.2:1:1.4 μL.min-I). Furthermore, a pleural effusion of 1.16:1:0.08 mL was detectable at elevated IPPs. The degree of edema formation in the anterior abdominal muscles (AAM) and the diaphragm (DIA) was largely insignificant during 15