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Peripheral relaxant activity of apomorphine and of a D1 selective receptor agonist on human corpus cavernosum strips

International Journal of Impotence Research volume 17, pages 127–133 (2005)Cite this article

Abstract

Apomorphine is used in the erectile dysfunction therapy and its action has been ascribed to the stimulation of central dopamine receptor. At the present stage, very little is known about the peripheral action of apomorphine on human corpus cavernosum (HCC). We have investigated the peripheral action of apomorphine and the role of dopamine receptors in HCC. We here demonstrate that both D1 and D2 receptors were expressed in the HCC, D1 receptors were two-fold more abundant than D2 and that both receptors were mainly localized on the smooth muscle cell component. Apomorphine in vitro exerted an anti-α1 adrenergic activity in human cavernosal strips since it prevented contraction induced by phenylephrine (PE), but not by U46619 or endothelin. Apomorphine elicited endothelium-independent and concentration-dependent relaxation of the strips contracted by PE, U46619 or endothelin. The EC50 values (μM) for apomorphine, in the presence and absence of endothelium, were 51.0±16 and 16.0±14, 120±19 and 150±18, 59.0±15 and 140±50 on PE-, U46619- or endothelin-induced contraction, respectively. Selective dopamine receptor agonist A-68930 (D1-like), but not quinpirole (D2-like), caused concentration-dependent relaxation of the cavernosal strips, which was partially prevented by endothelium removal or by treatment with an inhibitor of nitric oxide (NO) synthase. In conclusion, we show that (1) apomorphine has a peripheral relaxant direct effect as well as an antiadrenergic activity, (2) HCC possesses more D1-like (D1 and D5) than D2-like (D2, D3 and D4) receptors, (3) both D1- and D2-like receptors are mainly localized on smooth muscle cells and (4) the relaxant activity is most probably mediated by D1-like receptor partially through NO release from endothelium.

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Acknowledgements

We thank Abbott Italia for supporting this study.

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Authors and Affiliations

  1. Dipartimento di Farmacologia Sperimentale, Università di Napoli-Federico II, Napoli, Italia

    R d'Emmanuele di Villa Bianca, R Sorrentino, F Roviezzo & G Cirino

  2. Dipartimento di Urologia, Facoltà di Medicina, Università di Napoli-Federico II, Napoli, Italia

    C Imbimbo, A Palmieri & V Mirone

  3. Anatomia Patologica, Ospedale Cardarelli, Napoli, Italia

    G De Dominicis

  4. Dipartimento di Urologia, Università Vita-Salute San Raffaele, Milano, Italia

    F Montorsi

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  1. R d'Emmanuele di Villa Bianca
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  2. R Sorrentino
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  3. F Roviezzo
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  8. G Cirino
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  9. V Mirone
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Correspondence to G Cirino.

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d'Emmanuele di Villa Bianca, R., Sorrentino, R., Roviezzo, F. et al. Peripheral relaxant activity of apomorphine and of a D1 selective receptor agonist on human corpus cavernosum strips. Int J Impot Res 17, 127–133 (2005). https://doi.org/10.1038/sj.ijir.3901293

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  • DOI: https://doi.org/10.1038/sj.ijir.3901293

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