Cardiovascular effects of Acanthaster planci venom in the rat: possible involvement of PAF in its hypotensive effect.
Cardiovascular effects of the crowns-of-thorns starfish (Acanthaster planci) venom were examined in rats. The crude venom extracted from the spines of A. planci caused systemic hypotension associated with an increase in heart rate and a decrease in renal cortical blood flow when given i.v. The hypotensive effect of the venom was not inhibited by pretreatment with atropine, indomethacin or aprotinin, but was significantly inhibited by SRI 63-441, a platelet activating factor (PAF) antagonist. The venom caused dose-dependent vasorelaxation of the isolated rat aortic ring preparation precontracted by noradrenaline, an effect which was significantly attenuated by pretreatment with SRI 63-441, methylene blue or parabromophenacyl bromide. Denudation of the endothelium also diminished the vasorelaxing effect of the venom. Both the vasorelaxing and the hypotensive effects showed tachyphylaxis. These results suggest the release of PAF or a PAF-like substance from the endothelium by the venom.
Yara
A
A
Department of Pharmacology, School of Medicine, Faculty of Medicine, University of the Ryukyus, Okinawa, Japan.
Noguchi
K
K
Nakasone
J
J
Kinjo
N
N
Hirayama
K
K
Sakanashi
M
M
D000818:Animals; D001011:Aorta / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects*; D003864:Depression, Chemical; D004730:Endothelium, Vascular / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D009130:Muscle, Smooth / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D010972:Platelet Activating Factor / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012079:Renal Circulation / Q000187:drug effects; D013215:Starfish; D014688:Venoms / Q000494:pharmacology*
D010972:Platelet Activating Factor; D014688:Venoms