title: An examination of age-related changes in pre- and postsynaptic alpha-adrenoceptors in the rat isolated vas deferens.
abstract: Age-related changes in pre- and postsynaptic alpha-adrenoceptors were investigated in prostatic and epididymal portions of vasa deferentia from young adult (2-3 month) and 24 month old Sprague-Dawley rats, using the selective alpha 1-agonist amidephrine and the selective alpha 2-agonist xylazine. Effects of agonists were assessed against the isometric contraction to single pulse field stimulation. There was no change in the pre- or postsynaptic potency of amidephrine, but the presynaptic inhibitory potency of xylazine was significantly reduced in old rats. Therefore, in old rats there is a reduced sensitivity of presynaptic alpha 2- but no change in pre- or postsynaptic alpha 1-adrenoceptors and this may result in increased peripheral sympathetic neurotransmission.
mesh_terms: D000375:Aging; D000818:Animals; D004983:Ethanolamines / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000502:physiology*; D013843:Thiazines / Q000494:pharmacology*; D014649:Vas Deferens / Q000187:drug effects; D014991:Xylazine / Q000494:pharmacology*
chemical_list: D004983:Ethanolamines; D011942:Receptors, Adrenergic, alpha; D013843:Thiazines; D014991:Xylazine; C016980:amidephrine