Pulmonary hypertension and edema induced by platelet-activating factor in isolated, perfused rat lungs are blocked by BN52021

The experimental intravenous administration of platelet activating factor (PAF) induces pulmonary hypertension and directly or indirectly increases capillary permeability. Selective PAF antagonists BN52021 and L652-731 have been shown to inhibit the action of PAF in vitro and in vivo. Using a unique isolated perfused rat lung model, we measured the effect of these PAF antagonists on PAF-induced pulmonary hypertension and edema. Isolated rat lungs were perfused with Krebs-Henseleit solution. The right and left pulmonary arteries were dissected so that they could be perfused selectively, permitting the use of one lung as an internal control for a specific pharmacologic challenge. Exposure of one lung to PAF induced an increase of perfusion pressure and wet/dry lung weight ratio in a dose-dependent manner compared with the control lung. The PAF antagonists attenuated the increase in perfusion pressure and wet/dry lung weight caused by PAF (0.75 micrograms) in a dose-dependent manner. In addition, prostaglandin F2 alpha induced an equivalent increase in pulmonary pressure without causing a similar increase in lung edema. PAF-induced pulmonary hypertension and the increase in wet/dry lung weight ratio appear to be PAF receptor-mediated processes, and the use of specific antagonists and this technique may be useful probes to determine the role of PAF in pathophysiologic states.