Identification of alpha1-adrenoceptor subtypes involved in contraction of young CD rat epididymal vas deferens.
Contraction of rat epididymal vas deferens is regulated via a release of neurotransmitters from autonomic nerves and is mediated by alpha(1)-adrenoceptors. This study was directed to the characterization of alpha(1)-adrenoceptors involved in the contraction of the epididymal portion of young CD rat vas deferens, that were selectively discriminated in two populations through the irreversible blockade of two beta-chloroethyamines, 1 and 2. The antagonist activity of known subtype-selective alpha(1)-adrenoceptor antagonists, WB4101, 5-MU, and RS17053 (alpha(1A)), (+)-cyclazosin (alpha(1B)), and BMY7378 (alpha(1D)), was evaluated in the alpha(1)-adrenoceptors of the studied tissue as such and after pre-treatment with a proper discriminating concentration of beta-chloroetylamines 1 and 2, comparing the results with the affinities determined in classical Wistar rat models: prostatic vas deferens (alpha(1A)), spleen (alpha(1B)), and thoracic aorta (alpha(1D)). The results suggested that two alpha(1A)-adrenoceptors are involved in the contraction of the epididymal vas deferens of young CD rats. These may represent two alpha(1A)-adrenoceptor isoforms that are selectively and irreversibly blocked by beta-chloroetylamines 1 and 2, and reversibly antagonized by RS17053. The minor population, preferentially blocked by 1, seems correspond to a classical alpha(1A)-adrenoceptor subtype, while the major population, preferentially blocked by 2 and antagonized by RS17053 with low affinity, seems to correspond to an alpha(1L)-adrenoceptor.
Buccioni
Michela
M
Department of Chemical Sciences, University of Camerino, Camerino, Italy.
Kandhavelu
Meenakshisundaram
M
Angeli
Piero
P
Cristalli
Gloria
G
Dal Ben
Diego
D
Giardinà
Dario
D
Lambertucci
Catia
C
Lammi
Carmen
C
Volpini
Rosaria
R
Marucci
Gabriella
G
D058668:Adrenergic alpha-1 Receptor Antagonists; D000588:Amines / Q000494:pharmacology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004822:Epididymis / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D020128:Inhibitory Concentration 50; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D018340:Receptors, Adrenergic, alpha-1 / Q000145:classification* / Q000378:metabolism*; D014649:Vas Deferens / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
D058668:Adrenergic alpha-1 Receptor Antagonists; D000588:Amines; D018340:Receptors, Adrenergic, alpha-1; D009638:Norepinephrine