A highly potent and selective H3 agonist relaxes rabbit middle cerebral artery, in vitro.
An H3-agonist, R alpha methylhistamine strongly relaxed isolated and perfused rabbit middle cerebral artery precontracted with K+. This vasodilatation was not antagonized by either mepyramine or cimetidine but was competitively antagonized by an H3-antagonist, a mixture of impromidine and cimetidine. Histamine activated the H3-sites in this artery since its concentration-response curve (obtained with mepyramine and cimetidine) was parallel to that of R alpha methylhistamine. Our data indicate that H3-sites could exist in the rabbit cerebral artery.
Ea-Kim
L
L
Laboratoire de Pharmacologie, UFR de Pharmacie, Limoges, France.
Oudart
N
N
D000818:Animals; D002536:Cerebral Arteries / Q000187:drug effects; D002927:Cimetidine / Q000494:pharmacology; D006632:Histamine / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D017446:Impromidine; D066298:In Vitro Techniques; D008297:Male; D008761:Methylhistamines / Q000494:pharmacology*; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D011188:Potassium / Q000494:pharmacology; D011738:Pyrilamine / Q000494:pharmacology; D011817:Rabbits; D011968:Receptors, Histamine / Q000187:drug effects*
D007093:Imidazoles; D008761:Methylhistamines; D011968:Receptors, Histamine; D002927:Cimetidine; D006632:Histamine; D017446:Impromidine; D011738:Pyrilamine; D011188:Potassium; C048140:N-methylhistamine