1. ¹Department of Urology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
2. ²Department of Physiology and Biophysics, Seoul National University College of Medicine, Seoul, South Korea
3. ³Department of Urology, Chonbuk National University Medical School and Chonbuk National University Institute for Medical Sciences and Research Institute of Clinical Medicine of Chonbuk National University Hospital, Chonju, South Korea

Correspondence: Dr SW Lee, Department of Urology, Samsung Medical Center, Sungkyunkwan University School of Medicine, No 50, Irwon-Dong Gangnam-Gu, Seoul 135-710, South Korea. E-mail: drswlee@uasis.com

Received 10 March 2007; Revised 5 October 2007; Accepted 24 October 2007; Published online 20 December 2007.

Abstract

In this study, we investigated the effect of dopamine receptor agonists on potassium channels' activity and their signal transduction pathway in corporal smooth muscle cells. We used cultured human corporal smooth muscle cells. The whole cell and cell-attached configuration of the patch-clamp technique were used for electrophysiological recordings, and enzyme immunoassay was used for measuring cyclic AMP (cAMP) and cyclic GMP levels. Extracellular application of 10 M dopamine and apomorphine significantly increased whole-cell K⁺ currents by 283.555.7% (at +60 mV; n=12, P<0.001), 292.458.8.0% (at +60 mV; n=9, P<0.005), respectively. We confirmed that the increase in whole-cell currents was mainly due to activation of the tetraethylammonium-sensitive large conductance Ca²⁺-activated K⁺ channels (BK_Ca channels). Enzyme immunoassay indicated that dopamine and apomorphine stimulates cAMP levels in corporal smooth muscle cells in a concentration-dependent fashion. The activation of BK_Ca channels by dopamine receptor agonists in corporal smooth muscle cells might be one of the mechanisms in inducing penile erection.