Subtyping of α1-adrenoceptors responsible for the contractile response in the rat corpus cavernosum

Yat-Ching Tong, Juei Tang Cheng

Research output: Contribution to journalArticle

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Abstract

The subtyping of α1-adrenoceptors responsible for mediating contraction in isolated corpus cavernosum of mature male Wistar rats was studied pharmacologically. Concentration-response studies of the cavernosal smooth muscle to three agonists: methoxamine, norepinephrine and octopamine showed that methoxamine exhibited the highest potency in inducing contractile response; the respective pD2 values were: 6.22, 5.83 and 5.38. In the presence of 2-(2,6-dimethoxyphenoxyethyl)aminomethyl (WB4101), a specific antagonist for α(1A)-adrenoceptors, a parallel rightward shift of the concentration-response curve to methoxamine was observed. On the other hand, chloroethylclonidine (CEC) caused a rightward shift of the concentration-response curve to methoxamine with significant suppression of the maximum response. The pA2 value for WB4101 obtained from Schild plot was 9.03 ± 0.06 with slope (95% CL) equal to 0.955 (1.088-0.832). In the absence of extracellular calcium ions, the methoxamine-induced contraction was reduced by 92%. Ca2+-Channel blockers, nifedipine 10-6 M and diltazem 10-6 M decreased the contractile response by 18 and 23%, respectively. The present findings suggest that α(1A)-adrenoceptors are responsible for the methoxamine-induced contraction of the rat cavernosal smooth muscle.

Original languageEnglish
Pages (from-to)159-162
Number of pages4
JournalNeuroscience Letters
Volume228
Issue number3
DOIs
Publication statusPublished - 1997 Jun 13

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Methoxamine
Adrenergic Receptors
Smooth Muscle
Octopamine
Nifedipine
Wistar Rats
Norepinephrine
Ions
Calcium

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)

Cite this

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title = "Subtyping of α1-adrenoceptors responsible for the contractile response in the rat corpus cavernosum",
abstract = "The subtyping of α1-adrenoceptors responsible for mediating contraction in isolated corpus cavernosum of mature male Wistar rats was studied pharmacologically. Concentration-response studies of the cavernosal smooth muscle to three agonists: methoxamine, norepinephrine and octopamine showed that methoxamine exhibited the highest potency in inducing contractile response; the respective pD2 values were: 6.22, 5.83 and 5.38. In the presence of 2-(2,6-dimethoxyphenoxyethyl)aminomethyl (WB4101), a specific antagonist for α(1A)-adrenoceptors, a parallel rightward shift of the concentration-response curve to methoxamine was observed. On the other hand, chloroethylclonidine (CEC) caused a rightward shift of the concentration-response curve to methoxamine with significant suppression of the maximum response. The pA2 value for WB4101 obtained from Schild plot was 9.03 ± 0.06 with slope (95{\%} CL) equal to 0.955 (1.088-0.832). In the absence of extracellular calcium ions, the methoxamine-induced contraction was reduced by 92{\%}. Ca2+-Channel blockers, nifedipine 10-6 M and diltazem 10-6 M decreased the contractile response by 18 and 23{\%}, respectively. The present findings suggest that α(1A)-adrenoceptors are responsible for the methoxamine-induced contraction of the rat cavernosal smooth muscle.",
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Subtyping of α1-adrenoceptors responsible for the contractile response in the rat corpus cavernosum. / Tong, Yat-Ching; Cheng, Juei Tang.

In: Neuroscience Letters, Vol. 228, No. 3, 13.06.1997, p. 159-162.

Research output: Contribution to journalArticle

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