Peritoneal absorption of macromolecules studied by quantitative autoradiography.

Transport experiments of 125I-human serum albumin from the peritoneal cavity to the plasma were conducted in 200-g female rats. Blood and peritoneal samples were collected at intervals over 2-3 h. After death and rapid freezing of the animal, transverse sections were cut in a cryomicrotome from several tissues surrounding the peritoneal cavity, and the distribution of the labeled albumin was measured by computerized quantitative macroautoradiography. Tissue concentrations (counts/min per wet tissue wt) in parietal tissues (anterior abdominal wall and the diaphragm) were relatively constant versus distance from the peritoneum and represented a large fraction (0.5-1.0) of the concentration in the peritoneal cavity. Fractional concentrations in visceral tissues (liver, stomach, intestine) decreased from 0.20-0.35 at the peritoneal surface to 0.03-0.06 at a distance of 900 micron from the peritoneum. Uterine tissue concentrations lay between those of the parietal tissues and those of the viscera. The data are related to mechanisms of interstitial and lymphatic transport in these tissues.