Effect of prostaglandin E₁ on leukotriene C₄-induced increases in vascular permeability of hamster cheek pouch

Our goal was to determine whether there is a synergistic effect of prostaglandin E₁, (PGE₁) on eukotriene C₄ (LTC₄)-induced increases in vascular permeability of the hamster cheek pouch in vivo. Changes in permeability were quantified by counting venular leaky sites (LS) and calculating clearance (CLR) of fluorescein isothiocyanate (FITC)-dextran 70kDa, during suffusion of the cheek pouch with LTC₄ in the absence or presence of PGE₁,. LTC₄ produced a dose-related increase in LS and CLR, and PGE₁, (0.01 μM) significantly potentiated the effect of LTC₄. During suffusion with LTC₄ (15.0 nM) in the absence of PGE₁, LS increased from 0 to 19±3/0.11 cm² and CLR increased from 0.3±0.1 to 1.0±0.2 × 10^-6 ml/sec. During superfusion with LTC₄ (15.0 nM) in the presence of PGE₁, LS increased from 0 to 40±3/0.11 cm², and CLR increased from 0.4±0.1 to 2.1±0.5×10^-6 ml/sec. To determine whether the effect of PGE, on LTC₄-induced increases in vascular permeability was related to the vasodilatory effect of PGE₁, we examined the effect of isoproterenol (ISO). In contrast to that observed with PGE₁, ISO decreased LTC₄-induced increases in LS and CLR. Our data suggest that there is a synergistic effect of PGE₁, on LTC₄-induced increases in venular permeability that is not mediated by a vasodilatory action of PGE₁.