Characterization of post-junctional alpha-adrenoceptors in the rat isolated perfused femoral artery.
A comparison was made of contractile responses to alpha-adrenoceptor agonists in the rat aorta and in the rat isolated perfused femoral artery. Dose-response curves were constructed to noradrenaline (alpha 1/alpha 2), methoxamine (alpha 1-selective) and B-HT 920 (alpha 2-selective). Methoxamine behaved as a full agonist in both tissues as compared with noradrenaline, while B-HT 920 was only a partial agonist in the aorta and produced small responses in the femoral artery preparation which were not dose-dependent. pA2 or -log KB values were calculated for prazosin and idazoxan against noradrenaline and methoxamine. Similar -log KB values for prazosin against both agonists were obtained in both tissues, while idazoxan was approximately ten times more potent in the femoral artery preparation than in the aorta. These results suggest that the aorta contains a single population of alpha 1-adrenoceptors, while the perfused femoral artery preparation contains predominantly alpha 1-adrenoceptors but also a small population of alpha 2-adrenoceptors.
D000818:Animals; D001011:Aorta / Q000032:analysis / Q000187:drug effects; D001381:Azepines / Q000494:pharmacology; D004146:Dioxanes / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005263:Femoral Artery / Q000032:analysis / Q000187:drug effects*; D019329:Idazoxan; D066298:In Vitro Techniques; D008297:Male; D008729:Methoxamine / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000032:analysis / Q000187:drug effects*; D014661:Vasoconstriction / Q000187:drug effects
D001381:Azepines; D004146:Dioxanes; D011942:Receptors, Adrenergic, alpha; C024763:talipexole; D008729:Methoxamine; D009638:Norepinephrine; D011224:Prazosin; D019329:Idazoxan