We studied the effect of phosphatidylcholine (PDC) (50 mg/L) on the peritoneal ultrafiltration and permeability in vivo and in vitro. Our in vivo studies with normal rabbits confirmed previous observations of increased ultrafiltration mainly by decreasing the reabsorption phase. We observed no effect on glucose absorption rate. In in vitro studies, using isolated section of rabbit's mesentery, phosphatidylcholine increased the permeability of the mesothelium to water, urea and glucose from the vascular to the mesothelial side but not in the opposite direction. Following exposure of the peritoneal membrane to Alcian blue, a positively charged dye, phosphatidylcholine had no effect on mesothelial permeability. Our observations suggest that necessary for the action of phosphatidylcholine is its attachment to the anionic sites of the mesothelium. We speculate that improvement in UF is achieved by diminishing the thickness of the stagnant fluid layers trapped between the microvilli.
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