Study on the histamine-like activity of guanfacine.
The effects of guanfacine have been studied on guinea-pig isolated atria and diethylstilboestrol-treated rat isolated uterus to determine whether it possesses histamine-like activity. Guanfacine produced a concentration-dependent negative chronotropic effect which was not modified by ranitidine (0.1 microM). In rat isolated uterus contracted by KCl, clonidine (5-5000 microM) produced concentration-dependent relaxation which was blocked by ranitidine (0.1 microM), but guanfacine only produced relaxation at high concentrations (100-1000 microM), and this was not affected by ranitidine (0.1 microM). It is concluded that guanfacine, unlike clonidine, does not produce effects due to activation of H2-receptors in either guinea-pig atria or rat uterus.
Martinez-Mir
M I
MI
Departament de Farmacologia i Farmacotecnia, Universitat de Valencia, España.
Doñate
F
F
Estañ
L
L
Morales-Olivas
F J
FJ
Rubio
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E
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000818:Animals; D003000:Clonidine / Q000494:pharmacology; D004054:Diethylstilbestrol / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D016316:Guanfacine / Q000494:pharmacology*; D006168:Guinea Pigs; D006325:Heart Atria / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects*; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D014590:Uterine Contraction / Q000187:drug effects*
D000316:Adrenergic alpha-Agonists; D016316:Guanfacine; D011189:Potassium Chloride; D004054:Diethylstilbestrol; D003000:Clonidine