Alpha 1-adrenoceptor subtypes in aorta (alpha 1A) and liver (alpha 1B).
The effect of several alpha 1 adrenoceptor antagonists on the alpha 1-adrenoceptor-mediated stimulation of phosphatidylinositol labeling was studied comparatively in rat hepatocytes and rabbit aorta. It was observed that 5-methyl urapidil and WB 4101 were much more potent in rabbit aorta than in hepatocytes. The orders of potency were prazosin much greater than 5-methyl urapidil greater than or equal to WB 4101 in liver cells and WB 4101 greater than or equal to 5 methyl urapidil = prazosin in aorta. Treatment with chlorethylclonidine inhibited 70-80% of the stimulation of labeling induced by epinephrine in rat liver, but only 30-40% of that in aorta. Our data suggest the existence of two pharmacologically distinct receptors in these tissues i.e.m alpha 1A-adrenoceptors in aorta and alpha 1B in liver cells.
Torres-Márquez
M E
ME
Departamento de Bioenergética, Instituto de Fisiología Celular, UNAM, Mexico City, D.F.
Villalobos-Molina
R
R
García-Sáinz
J A
JA
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D003000:Clonidine / Q000031:analogs & derivatives / Q000494:pharmacology; D004146:Dioxanes / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D066298:In Vitro Techniques; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000378:metabolism; D010879:Piperazines / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011817:Rabbits; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*
D000317:Adrenergic alpha-Antagonists; D004146:Dioxanes; D010716:Phosphatidylinositols; D010879:Piperazines; D011942:Receptors, Adrenergic, alpha; C057446:5-methylurapidil; C051731:chlorethylclonidine; C010654:(2-(2',6'-dimethoxy)phenoxyethylamino)methylbenzo-1,4-dioxane; D003000:Clonidine; D011224:Prazosin; D004837:Epinephrine