PAF induces relaxation of pulmonary arteries but contraction of pulmonary veins in the ferret.
The present study was designed to determine whether platelet-activating factor (PAF) has different effects on pulmonary arteries and veins. Third-order pulmonary arterial and venous rings of the ferret were suspended in organ chambers filled with modified Krebs-Ringer bicarbonate solution (95% O2-5% CO2, 37 degrees C) and their isometric tension was recorded. Under basal conditions, PAF had no effect on the resting tension of arteries but induced an endothelium-dependent contraction of veins. The contraction was not affected by BW-755C (an inhibitor of cyclooxygenase and lipoxygenase), BQ-123 [an antagonist of endothelin (ET) A (ETA) receptors)], or IRL-1038 (an antagonist of ETB receptors). PAF had no effect on veins during contraction to prostaglandin F2 alpha (PGF 2 alpha) but induced an endothelium-dependent relaxation of arteries. The relaxation was abolished by N omega-nitro-L-arginine. Incubation with PAF for 30 min augmented contractions of veins with endothelium to PGF 2 alpha. The augmentation was not affected by BW-755C, BQ-123, or IRL-1038. Pretreatment with PAF had no effect on the response of veins to phenylephrine or on the response of arteries to either PGF 2 alpha or phenylephrine. These observations demonstrated that, in the ferret, PAF affected differently the response of pulmonary arteries and veins and that the endothelium plays a critical role in the PAF-induced effects. Furthermore, the PAF-induced effects appear not to be mediated by metabolites of arachidonic acid and ET.
Gao
Y
Y
Department of Pediatrics, University of California, Los Angeles (UCLA) School of Medicine, USA.
Zhou
H
H
Raj
J U
JU
D000818:Animals; D004730:Endothelium, Vascular / Q000502:physiology; D005289:Ferrets; D066298:In Vitro Techniques; D008297:Male; D010972:Platelet Activating Factor / Q000494:pharmacology*; D011651:Pulmonary Artery / Q000187:drug effects*; D011667:Pulmonary Veins / Q000187:drug effects*; D014661:Vasoconstriction; D014664:Vasodilation
D010972:Platelet Activating Factor