EFFECT OF HYPERCARBIA ON SURFACE-PROTEINS OF CULTURED BOVINE ENDOTHELIAL-CELLS

Hypercarbia is a common complication of respiratory failure, and the t echnique of ''permissive hypercapnia'' is used to ventilate individual s with increased peak airway pressures on mechanical ventilators, resu lting in elevated arterial PCO2. We studied the effects of hypercarbia on cultured bovine aortic and main pulmonary artery endothelial cell surface proteins, assessing cell surface iodination using lactoperoxid ase bound to latex microspheres. We found that 4 h of exposure to 10% CO2 increased the display of substances of apparent molecular masses o f 27, 47, and 52 kDa. This effect was not mimicked by acidotic media. Western blots of detergent extracts of main pulmonary artery endotheli al cell monolayers did not show increased expression of carbonic anhyd rase TV (molecular mass = 52 kDa) after incubation under hypercarbic c onditions. Hypercarbia did not change the pattern of [S-35]methionine incorporation into endothelial cell proteins. We conclude that hyperca rbia of 4-h duration changes iodinated endothelial cell surface protei ns. We speculate that this effect may be related to changes in secreti on or display of apical cell membrane-associated proteins.