title: Characterization of alpha-adrenoceptors mediating sympathetic vasoconstriction in rat autoperfused hindlimb: effects of SK&F 104078.
abstract: In the autoperfused hindlimb of pithed rats, vasoconstrictor responses to intra-arterial infusions of the selective alpha 2-adrenoceptor agonist, B-HT 933, were antagonized by the alpha 2-adrenoceptor antagonist, rauwolscine (1 mg/kg i.v.), and by the selective postjunctional alpha 2-adrenoceptor antagonist, SK&F 104078 (1 mg/kg), but not by the selective alpha 1-adrenoceptor antagonist, prazosin (0.1 mg/kg). In contrast, responses to the selective alpha 1-adrenoceptor agonist, methoxamine, were antagonized by prazosin, but not by rauwolscine or SK&F 104078. Vasopressor responses to stimulation of sympathetic nerves were inhibited by prazosin, increased by rauwolscine, and not affected by SK&F 104078. The results indicate that vascular neuroeffector transmission in rat hindlimb is mediated by postjunctional alpha 1-adrenoceptors, and that SK&F 104078 is a selective antagonist of postjunctional alpha 2-adrenoceptor, and lacks the prejunctional alpha 2-adrenoceptor antagonist action of rauwolscine.
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D001381:Azepines / Q000494:pharmacology; D001552:Benzazepines / Q000494:pharmacology*; D008297:Male; D008729:Methoxamine / Q000494:pharmacology; D010477:Perfusion; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects* / Q000502:physiology; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects*; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D000317:Adrenergic alpha-Antagonists; D001381:Azepines; D001552:Benzazepines; D011942:Receptors, Adrenergic, alpha; C054935:SK&F 104078; D015016:Yohimbine; C015603:azepexole; D008729:Methoxamine; D011224:Prazosin