Effects of BN 52063 and other agents inhibiting platelet-activating factor-induced contractile responses in rat portal vein.
Platelet-activating factor (PAF-acether) is a potent agonist (EC50: 3.2 x 10(-8) M) of isolated rat portal vein. BN 52063 (composed of BN 52020, BN 52021 and BN 52022; molar ratio 2:2:1) specifically inhibits PAF-acether (10(-7) M) induced tone (IC50: 3.9 x 10(-5) M). Salbutamol (IC50: 3.1 x 10(-7) M), forskolin (IC50: 3.1 x 10(-6) M) and theophylline (IC50: 2.25 x 10(-4) M) are also effective in inhibiting PAF-acether-induced contractile responses and all excepting forskolin, show a certain specificity in this action. The basal myogenic activity of the rat portal vein is dose-dependently decreased by salbutamol (IC50: 1.2 x 10(-7) M), forskolin (IC50: 2.6 x 10(-6) M) and theophylline (IC50: 2.3 x 10(-4) M) whereas BN 52063 has no effect. The data suggest that rat portal veins possess specific PAF-acether receptors sensitive to BN 52063 and that PAF-acether effects could be inhibited by compounds which can bypass these putative receptors and modulate cAMP levels.
Hellegouarch
A
A
I.H.B. Research Labs, ZA de Courtaboeuf, Les Ulis, France.
Auguet
M
M
Clostre
F
F
Braquet
P
P
D000420:Albuterol / Q000494:pharmacology; D000818:Animals; D005576:Colforsin / Q000494:pharmacology; D066298:In Vitro Techniques; D007783:Lactones; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D010936:Plant Extracts / Q000494:pharmacology*; D010972:Platelet Activating Factor / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D011169:Portal Vein / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D013806:Theophylline / Q000494:pharmacology
D007783:Lactones; D010936:Plant Extracts; D010972:Platelet Activating Factor; C050422:BN 52063; D005576:Colforsin; D013806:Theophylline; D000420:Albuterol