Electrolyte and Fluid Transport in Mesothelial Cells

Abstract

Mesothelial cells are specialized epithelial cells, which line the pleural, pericardial, and peritoneal cavities. Accumulating evidence suggests that the monolayer of mesothelial cells is permeable to electrolyte and fluid, and thereby govern both fluid secretion and re-absorption in the serosal cavities. Disorders in these salt and fluid transport systems may be fundamental in the pathogenesis of pleural effusion, pericardial effusion, and ascites. In this review, we discuss the location, physiological function, and regulation of active transport (Na(+)-K(+)-ATPase) systems, cation and anion channels (Na(+), K(+), Cl(-), and Ca(2+) channels), antiport (exchangers) systems, and symport (co-transporters) systems, and water channels (aquaporins). These secretive and absorptive pathways across mesothelial monolayer cells for electrolytes and fluid may provide pivotal therapeutical targets for novel clinical intervention in edematous diseases of serous cavities.

Fig. 1

Electrolyte and fluid transport systems reported in mesothelial cells. The location of ion transport systems is indicated in either the apical or basolateral membrane. The specific inhibitor for each transport pathway is shown. AQP, aquaporins. Please see the legends of Table 1 and 2 for the full names of other abbreviations.

Fig. 2

Histology of human pleural mesothelial cells (adapted from Cagle and Churg with permission from Archives of Pathology & Laboratory Medicine. Copyright 2005. College of American Pathologists [34]). A. Type I mesothelial cells. High-power view shows flat, inconspicuous normal mesothelial cells lining the visceral pleural surface (hematoxylin-eosin, original magnification ×300). B. Type II mesothelial cells. A more conspicuous layer of relatively bland cuboidal cells regularly spaced along the pleural surface (hematoxylin-eosin, original magnification ×350).