Pharmacological characterization of adrenoceptors in horse corpus cavernosum penis.
1. The presence and types of alpha and beta-adrenoceptors in the corpus cavernosum of the horse were studied in vitro by using selected ligands of adrenoceptors and isometric tension recording. 2. Noradrenaline and phenylephrine induced concentration-dependent contractions in corpus cavernosum preparations. B-HT 920 had no effect. 3. Phentolamine and prazosin produced a shift to the right of the dose-response curve of noradrenaline, while the alpha(2)-antagonist, rauwolscine had no effect on the response to noradrenaline. Phenylephrine-evoked contractions of corporal strips were significantly inhibited by the alpha(1)-adrenoceptor antagonist, prazosin. 4. Isoprenaline and salbutamol each relaxed precontracted corpus cavernosum preparations in a concentration-dependent manner; the isoprenaline effect was blocked by propranolol, practolol and butoxamine. The salbutamol effect was blocked by butoxamine. 5. These results suggest that presence of postjunctional alpha(1)-adrenoceptors in horse corpus cavernosum. There is also a heterogenous population of beta-adrenoceptors in this tissue, belonging to the beta(1) and beta(2) subtypes.
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Departamento de Fisiología, Facultad de Veterinaria, Universidad Complutense, Madrid, Spain.
López
P G
PG
Fernández
J L
JL
Garcia-Sacristán
A
A
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D006736:Horses / Q000033:anatomy & histology*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009130:Muscle, Smooth / Q000187:drug effects / Q000648:ultrastructure*; D010413:Penis / Q000187:drug effects / Q000648:ultrastructure*; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects* / Q000502:physiology; D011943:Receptors, Adrenergic, beta / Q000187:drug effects* / Q000502:physiology
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta