Use of transgenic (knockout) mice reveals a site distinct from the alpha2A-adrenoceptors for agmatine in the vas deferens.
The inhibitory effect of agmatine on electrically induced contractions was studied in vas deferens of Adra 2a transgenic mice lacking alpha(2A)-adrenoceptors. Agmatine and clonidine caused a concentration-dependent inhibition of twitches. However, while agmatine showed a similar pIC(50) value in control and transgenic mice, the pIC(50) value for clonidine was about 30-fold lower in knockout mice. In both strains, yohimbine shifted the curve for clonidine, but not for agmatine, even when a 100-fold higher concentration of yohimbine was employed. Our results indicate that inhibition by agmatine in mouse vas deferens is not simply due to interactions with alpha(2)-adrenoceptors in our experimental conditions.
Santos
Wilson C
WC
Departamento de Farmácia e Administração Farmaceutica, Faculdade de Farmácia, Universidade Federal Fluminense, Rua Mário Viana, 523-Santa Rosa, CEP 24241-000, Niterói, RJ, Brasil. wsantos@vm.uff.br
Garcez-do-Carmo
Lucia
L
da Silva
Eliane C
EC
de Pascual
Ricardo
R
Jurkiewicz
Neide H
NH
Jurkiewicz
Aron
A
Gandía
Luis
L
D000376:Agmatine / Q000494:pharmacology*; D000818:Animals; D003000:Clonidine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009119:Muscle Contraction / Q000187:drug effects; D018341:Receptors, Adrenergic, alpha-2 / Q000187:drug effects / Q000502:physiology*; D014649:Vas Deferens / Q000187:drug effects* / Q000502:physiology
C547769:Adra2a protein, mouse; D018341:Receptors, Adrenergic, alpha-2; D000376:Agmatine; D003000:Clonidine