The functional alpha-adrenoceptor in dog caudal vesical arteries is mainly an alpha1A subtype.
1 The present study attempted to pharmacologically characterize the subtypes of alpha-adrenoceptors mediating the vasoconstriction in the isolated and perfused canine vesical artery. 2 Noradrenaline (NA) and phenylephrine (PE, an alpha1-adrenoceptor agonist) induced a dose-dependent vasoconstriction, whereas xylazine (an alpha2-agonist) did not induce any clear vascular constrictor response. 3 Prazosin at 0.01 microM and rauwolscine at 0.1 microM failed to affect the NA-induced vasoconstriction. Prazosin at 0.1 microM antagonized the vasoconstrictor responses to NA, with pKB value of 7.8. 4 WB 4101 at 0.01-0.1 microM dose-dependently inhibited the responses to NA, with a pKB value of 8.9. The vasoconstrictor responses to NA were not significantly affected by chloroethylclonidine (10-30 microM) or BMY 7378 (0.1 microM). 5 The present results indicate that the canine vesical arteries dominantly contain alpha1-adrenoceptors but have no alpha2-adrenoceptors, and the functional subtype of alpha1-adrenoceptor is characterized as an alpha1A-adrenoceptor subtype.
Nakazawa
M
M
Department of Pharmacology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan.
Taguchi
Y
Y
Yang
X P
XP
Chiba
S
S
D058646:Adrenergic alpha-1 Receptor Agonists; D058668:Adrenergic alpha-1 Receptor Antagonists; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D001158:Arteries / Q000187:drug effects / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects; D003000:Clonidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004146:Dioxanes / Q000494:pharmacology; D004285:Dogs; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D009638:Norepinephrine / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D018340:Receptors, Adrenergic, alpha-1 / Q000502:physiology*; D012039:Regional Blood Flow / Q000187:drug effects; D001743:Urinary Bladder / Q000098:blood supply; D014991:Xylazine / Q000494:pharmacology; D015016:Yohimbine / Q000494:pharmacology
D058646:Adrenergic alpha-1 Receptor Agonists; D058668:Adrenergic alpha-1 Receptor Antagonists; D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D004146:Dioxanes; D010879:Piperazines; D018340:Receptors, Adrenergic, alpha-1; D010656:Phenylephrine; D014991:Xylazine; D015016:Yohimbine; C051731:chlorethylclonidine; C010654:(2-(2',6'-dimethoxy)phenoxyethylamino)methylbenzo-1,4-dioxane; C053428:BMY 7378; D003000:Clonidine; D009638:Norepinephrine; D011224:Prazosin