title: Rilmenidine differs from clonidine in that it lacks histamine-like activity.
abstract: Studies were carried out to determine whether rilmenidine, a recently introduced antihypertensive agent with a similar mechanism of action of clonidine, possesses histamine-like activity on tissues responding to histamine H2-receptor agonists. In guinea-pig isolated atria, both histamine and clonidine caused concentration-dependent positive chronotropic effects which were blocked by the histamine H2-receptor antagonist cimetidine (5 microM); in contrast, rilmenidine produced a concentration-dependent negative chronotropic effect which was not altered by cimetidine. In stilboestrol-treated rat isolated uterus contracted by KCl, histamine and clonidine produces concentration-dependent relaxations which were blocked by cimetidine (5 microM); rilmenidine also produced relaxation, but this was not affected by cimetidine (5 microM). These findings suggest that rilmenidine, unlike clonidine, does not activate histamine H2-receptors in either guinea-pig atria or rat uterus.
authors.affiliation: Department of Pharmacology, University of Melbourne, Vic., Australia.
authors.forename: C G
authors.initials: CG
authors.lastname: Li
authors.forename: M J
authors.initials: MJ
authors.lastname: Rand
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000818:Animals; D003000:Clonidine / Q000494:pharmacology*; D005260:Female; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006632:Histamine / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009206:Myocardium / Q000378:metabolism; D010080:Oxazoles / Q000494:pharmacology*; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011970:Receptors, Histamine H2 / Q000187:drug effects / Q000378:metabolism; D000077769:Rilmenidine; D014590:Uterine Contraction / Q000187:drug effects; D014599:Uterus / Q000187:drug effects / Q000378:metabolism
chemical_list: D000316:Adrenergic alpha-Agonists; D010080:Oxazoles; D011970:Receptors, Histamine H2; D011189:Potassium Chloride; D006632:Histamine; D003000:Clonidine; D000077769:Rilmenidine