Platelet activating factor modulates peptidoleukotriene effects on the permeability of bovine aortic endothelial cell to albumin

The purpose of the present experiments was to study the potency of various inflammatory mediators to modulate the clearance rate of¹²⁵I-albumin through bovine aortic endothelial cell (BAEC) monolayer on polycarbonate micropore membrane. The incubation of BAEC with LTD₄ (10⁻⁸–10⁻⁶M) increased dose-dependently the permeability to radioactive albumin. The effect was potentiated by addition of PAF (10⁻⁵M). LTC₄ had a less potent action on the clearance rate of¹²⁵I-albumin, since only the highest dose of LTC₄ used (10⁻⁶M) had a significant effect, and it was not potentiated by PAF (10⁻⁵M). The treatment with PAF alone at concentration up to 10⁻⁵M did not increase the¹²⁵I-albumin clearance rate. Our results suggest that BAEC may bear specific receptors for LTC₄ and LTD₄ or that LTC₄ is not converted to LTD₄ by BAEC. Our results also suggest that LTD₄ could possibly stimulate the expression of PAF receptors on BAEC.