Platelet-activating factor (PAF-acether) and microcirculation: effect of Lyso-PAF and PAF-antagonists.
Topical application of a standard dose of noradrenaline (NA) to the anesthetized rat mesentery evoked a vasoconstrictor response the latency of which was increased in a dose-dependent way by previous addition of PAF-acether or histamine but not by Lyso-PAF. Lyso-PAF, however, blocked the antagonistic effect of PAF-acether to NA, the blockade being equivalent to that observed with PAF-antagonists (BN 52021 or WEB 2086) either injected iv, or applied topically. In contrast, the antagonistic action of histamine towards NA was not affected by Lyso-PAF or PAF-antagonists. Since platelet aggregation and leukocyte accumulation did not occur, PAF-acether appears to interact directly with microvessels to block vasoconstrictor stimuli, an effect antagonized by PAF-antagonists and the metabolite/precursor, Lyso-PAF.
Lagente
V
V
Departamento de Farmacologia, Universidade de São Paulo, Brasil.
Fortes
Z B
ZB
Garcia-Leme
J
J
Vargaftig
B B
BB
D000818:Animals; D001381:Azepines / Q000494:pharmacology; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects*; D008833:Microcirculation; D009638:Norepinephrine / Q000494:pharmacology*; D010972:Platelet Activating Factor / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors*; D051381:Rats; D011919:Rats, Inbred Strains; D014227:Triazines / Q000494:pharmacology; D014230:Triazoles; D014661:Vasoconstriction / Q000187:drug effects*
D001381:Azepines; C029271:O-deacetyl platelet activating factor; D010972:Platelet Activating Factor; D014227:Triazines; D014230:Triazoles; C052518:WEB 2086; D009638:Norepinephrine