Evidence for the role of alpha1D- and alpha1A-adrenoceptors in contraction of the rat mesenteric artery.
We investigated the alpha(1)-adrenoceptor subtype(s) involved in contraction of the isolated rat mesenteric artery by the use of the agonists noradrenaline (NA), phenylephrine (PHE), oxymetazoline (OXY), and methoxamine (MET), the competitive antagonists 8-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-8-azaspiro(4.5)decane-7,9-dione dihydrochloride (BMY 7378) and 5-methylurapidil, and the alkylating agent chloroethylclonidine (CEC). Agonists showed the potency order NA> or =PHE>OXY>MET; pA(2) values for 5-methylurapidil and BMY 7378 were 7.74+/-0.11 and 8.72+/-0.28, respectively, while Schild slopes were not different than unity; alpha(1)-adrenoceptor alkylation with CEC showed a drastic decrease in maximal agonists-induced contraction and a shift to the right of about 46-, 122-, 2-, and 15-fold higher than controls for NA, PHE, OXY, and MET, respectively. Data suggest that alpha(1D)-adrenoceptors predominate for contraction in mesenteric artery of the Wistar rat, with a second population of alpha(1A)-adrenoceptors responding at high agonist concentrations.
Arévalo-León
Luz Elena
LE
Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Mich., Mexico.
Gallardo-Ortíz
Itzell A
IA
Urquiza-Marín
Héctor
H
Villalobos-Molina
Rafael
R
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D003000:Clonidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects* / Q000502:physiology; D008729:Methoxamine / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology; D010109:Oxymetazoline / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D018340:Receptors, Adrenergic, alpha-1 / Q000187:drug effects / Q000502:physiology*
C547715:Adra1a protein, rat; C547721:Adra1d protein, rat; D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D010879:Piperazines; D018340:Receptors, Adrenergic, alpha-1; C057446:5-methylurapidil; D010656:Phenylephrine; C051731:chlorethylclonidine; D010109:Oxymetazoline; D008729:Methoxamine; C053428:BMY 7378; D003000:Clonidine; D009638:Norepinephrine