title: Inhibition of intravascular platelet aggregation in the rat by adrenaline.
abstract: Intravascular platelet aggregation to adenosine diphosphate (ADP) was measured in anesthetized rats using 111indium-labelled platelets. Acute adrenalectomy increased the aggregatory effect of ADP in vivo, whereas infusions of low concentrations of adrenaline into adrenalectomized rats suppressed ADP-induced platelet aggregation. Similar antiaggregatory effects were seen with the alpha 2 agonist B-HT 933 and the alpha 1 agonist methoxamine, but not with isoprenaline. The effect of adrenaline was inhibited by phentolamine, yohimbine, the selective alpha 2 adrenoceptor antagonist WY 26392 and by indomethacin, but not by propranolol or prazosin. Adrenaline thus inhibits ADP-induced aggregation in vivo by a mechanism that may involve stimulation of an alpha 2 adrenoreceptor and may be dependent on activation of cyclooxygenase enzyme.
authors: Department of Pharmacology, King's College, London, U.K.
authors: J H
authors: JH
authors: Botting
authors: A O
authors: AO
authors: Oyekan
authors: F
authors: F
authors: Hammady
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000311:Adrenal Glands / Q000502:physiology; D000818:Animals; D001012:Aorta, Abdominal; D004837:Epinephrine / Q000494:pharmacology*; D007213:Indomethacin / Q000494:pharmacology; D007275:Injections, Intravenous; D008297:Male; D008751:Methylene Blue / Q000494:pharmacology; D010975:Platelet Aggregation Inhibitors; D051381:Rats; D011919:Rats, Inbred Strains; D013565:Sympatholytics / Q000494:pharmacology; D013566:Sympathomimetics / Q000494:pharmacology
chemical_list: D010975:Platelet Aggregation Inhibitors; D013565:Sympatholytics; D013566:Sympathomimetics; D000244:Adenosine Diphosphate; D008751:Methylene Blue; D007213:Indomethacin; D004837:Epinephrine