The alpha(1A)-adrenoceptor subtype mediates contraction in rat femoral resistance arteries.
In this study, alpha(1)-adrenoceptor subtypes were characterised in rat femoral resistance arteries mounted on a small vessel myograph. A-61603 was found to be more potent than noradrenaline and phenylephrine in these arteries. Brimonidine (UK 14304) could not evoke any contractile responses and the sensitivity to noradrenaline and phenylephrine was not affected by (8aR,12aS,13aS)-5,8,8a,9,10,11,12,12a,13a-decahydro-3-methoxy-12-(ethylsulphonyl)-6H-isoquino[2,1-g][1,6]-naphthyridine (RS 79948), ruling out the presence of alpha(2)-adrenoceptors. Prazosin, 5-methyl-urapidil and 2-([2,6-dimethoxyphenoxyethyl]aminomethyl)-1,4-benzodioxane (WB 4101) produced rightward shifts in the sensitivity to noradrenaline, giving pA(2) values of 9.6, 9.4 and 10.4, respectively, in agreement with the presence of alpha(1A)-adrenoceptors. (8-[2-[4-(2-Methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4.5]decane-7,9-dione (BMY 7378; 1 microM) produced a small shift in the sensitivity of noradrenaline giving a pK(B) of 7.2. In the presence of 300 nM 5-methyl-urapidil, sensitivity to noradrenaline was not further shifted by 1 microM BMY 7378. Responses to noradrenaline were unaffected by the alpha(1B)-adrenoceptor alkylating agent chloroethylclonidine (1 microM). These results suggest alpha(1A)-adrenoceptors mediate contractile responses to noradrenaline in rat femoral resistance arteries.
Jarajapu
Y P
YP
Vascular Assessment Group, School of Biological and Biomedical Sciences, Glasgow Caledonian University, Cowcaddens Road, Glasgow G4 0BA, Scotland, UK.
Hillier
C
C
MacDonald
A
A
D058646:Adrenergic alpha-1 Receptor Agonists; D058668:Adrenergic alpha-1 Receptor Antagonists; D058669:Adrenergic alpha-2 Receptor Antagonists; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D000068438:Brimonidine Tartrate; D003000:Clonidine / Q000031:analogs & derivatives / Q000494:pharmacology; D004146:Dioxanes / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005263:Femoral Artery / Q000187:drug effects / Q000502:physiology*; D007093:Imidazoles / Q000494:pharmacology; D066298:In Vitro Techniques; D007546:Isoquinolines / Q000494:pharmacology; D008297:Male; D009287:Naphthyridines / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D018340:Receptors, Adrenergic, alpha-1 / Q000502:physiology*; D013764:Tetrahydronaphthalenes / Q000494:pharmacology; D014655:Vascular Resistance; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*
C094643:A 61603; C547715:Adra1a protein, rat; D058646:Adrenergic alpha-1 Receptor Agonists; D058668:Adrenergic alpha-1 Receptor Antagonists; D058669:Adrenergic alpha-2 Receptor Antagonists; D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D004146:Dioxanes; D007093:Imidazoles; D007546:Isoquinolines; D009287:Naphthyridines; D010879:Piperazines; D011810:Quinoxalines; C104875:RS 79948-197; D018340:Receptors, Adrenergic, alpha-1; D013764:Tetrahydronaphthalenes; C057446:5-methylurapidil; D010656:Phenylephrine; C051731:chlorethylclonidine; D000068438:Brimonidine Tartrate; C010654:(2-(2',6'-dimethoxy)phenoxyethylamino)methylbenzo-1,4-dioxane; C053428:BMY 7378; D003000:Clonidine; D009638:Norepinephrine; D011224:Prazosin