Permeability of the diaphragm and fluid resorption from the peritoneal cavity in the rat

The ability to remove fluid from the peritoneal cavity is greatly impaired in rats after sealing the diaphragm (abrading such that fibrous tissue forms). The in vivo resorptive capacity of rats with sealed diaphragms was significantly reduced from 12.3 +/- 1.77% . hr-1 in controls to 5.05 +/- 2.53% . hr-1 in rats with sealed diaphragms. The in vitro permeability of isolated diaphragms for mannitol, inulin, and dextrans of mol wt 16,000 and 75,000 was 4.69 +/- 0.74, 1.16 +/- 0.22, 0.54 +/- 0.11, and 0.22 +/- 0.04 cm . sec-1 . 10(-6) for controls, and 0.54 +/- 0.24, 0.19 +/- 0.19, 0.09 +/- 0.03, and 0.08 +/- 0.02 cm . sec-1 . 10(-6) for sealed diaphragms, respectively. The reduction in the permeability of the fibrosed diaphragm to larger molecules could account for the reduced resorptive capacity.