Exaggerated Protein Loss Complicating Sterile Peritonitis Results from Increased Diffusion

Abstract

To assess the mechanism of protein loss during chemical peritonitis, dialyses with sodium desoxycholate added to the instilled solution were compared to controls in rabbits. Sodium desoxycholate caused an inflammatory reaction characterized by increased protein loss, leukocyte exudation, decreased ultrafiltration and increased clearance of solutes including neutral dextrans. It is suggested that increased protein loss accompanying peritonitis which is due to increased diffusion through capillaries unrelated to effects of membrane anionic charge. Exaggerated protein loss is a recognized sequel of the peritonitis that complicates peritoneal dialysis (I, 2). Such excessive protein loss can contribute to malnutrition, impeding recovery from infection. It has been assumed that the augmented protein loss is due to increased diffusion but this has not been verified. Secretion from inflammed cells adjacent to the peritoneum could account for increased protein loss. Enhanced transfer of plasma proteins across the capillary wall may be due to an overall increase in permeability following capillary dilation which stretches pores, or alternatively it might represent a loss of the anionic charges, which line the pores and retard transport of anionic macromolecules. Previously the transfer rate of polydispersed dextrans from plasma to peritoneal dialysate has been used to assess peritoneal porosity, presumably reflecting capillary-wall permeability (3). The transfer of neutral dextrans should not be inhibited by the fixed anionic charges of the capillary wall interstices. Moreover, these carbohydrates would not be secreted by injured cells; their distribution is extracellular. An increased rate of transfer from plasma to peritoneal dialysate should indicate enhanced diffusion, when there is no increase in convective transport accompanying ultrafiltration. Sodium desoxycholate, the solvent used with amphotericin B, is an irritant that has been shown to induce a sterile peritonitis characterized by dialysate leukocytosis, increased diffusion of small solutes such as urea, and decreased ultrafiltration, owing to the loss of the glucose-induced osmotic gradient (4). These studies were designed to determine whether sodium desoxycholate would increase the peritoneal transfer rate of neutral dextrans from plasma to dialysate. The higher rate of dextran transfer observed with this agent is interpreted to support the hypothesis that proteins, lost excessively during peritonitis, derive from plasma.