BIDIRECTIONAL PERITONEAL TRANSPORT OF IMMUNOGLOBULIN IN RATS - COMPARTMENTAL KINETICS

Protein transport to and from fluid in the peritoneal cavity is observed during clinical procedures. Dialysate osmolality is a major determinant of net fluid flux into the cavity. We carried out experiments in rats to determine the plasma, peritoneal, and tissue concentrations of immunoglobulin (Ig) G resulting from either intravenous (iv) or intraperitoneal (ip) administration during hypertonic or isotonic dialyses. After iv injection of IgG, overall mass transfer into the cavity was not affected by the osmolality. After ip injection, tissue concentrations were dependent on the dialysis duration. Protein absorption from the hypertonic dialysate into the surrounding tissue was quantitatively less than the absorption from an isotonic dialysis solution at 20 min. By 200 min, total protein transport was not affected by dialysate osmolality. Lymphatic transport to the plasma amounted to 20-25% of the total protein loss from the peritoneal cavity; approximately 60% of the absorbed dose was found in tissues surrounding the cavity at both 20 and 200 min, with particularly high concentrations in parietal areas. We conclude that immunoglobulin transport in the peritoneal tissue, resulting from either iv or ip injection, is influenced by route of administration but is little affected by dialysate osmolality. Peritoneal absorption of proteins occurs directly into the surrounding tissue interstitial space as a result of hydrostatic pressure-driven convection and diffusion.