SURFACTANT BARRIER LINING PERITONEAL MESOTHELIUM - LUBRICANT AND RELEASE AGENT

Objective: Five studies are described to determine whether there is an outermost lining of surface-active phospholipid (SAPL) adsorbed to th e peritoneum and to quantify its ability to act as a release (antistic k) agent and boundary lubricant by standard tests. Methods: Using a hy drophobic probe (phosphin E), epifluorescence microscopy was used to d emonstrate an outermost lining of oligolamellar SAPL by spectral analy sis of the emitted light, a finding consistent with the appreciable hy drophobicity demonstrated on canine peritoneal mesothelium and its vir tual elimination by incubation with bile salt. Good release and excell ent lubricating capabilities of human peritoneal SAPL have been quanti fied as the release factor and coefficient of friction, respectively, by standard tests from the physical sciences. Results: A well-defined outermost layer was clearly visible on peritoneal mesothelium whose co lor spectrum was identical to that produced by pure phosphatidylcholin e ultrasonicated into its oligolamellar state. Further evidence for a SAPL lining was demonstrated by a parietal contact angle of 43 degrees (47 degrees visceral) on this surface and its virtual elimination by incubation with dilute bile salt. Human SAPL from continuous ambulator y peritoneal dialysis (CAPD) effluent proved an effective release agen t, reducing adhesion by 67%, and an excellent lubricant as quantified by a coefficient of friction of 0.091 under load (1.9 kg/cm(2)). Concl usions: The good release and excellent lubricating properties of SAPL adsorbed to mesothelial surfaces are highly desirable in reducing wear and exfoliation of epithelial cells. In spanning epithelial cells, th e same lining might also serve to render tight junctions tight and red uce macromolecular escape while compatible with many aspects of CAPD, including lipid permeability and conflicting results obtained from adm inistering exogenous SAPL.