Abstract
The mechanism by which yohimbine relaxes the human corpus cavernosum remains unclear. Using the human corpus cavernosum strips immersed in isometric baths containing Krebs–Henseleit solution, this study investigates the effect of yohimbine on the relaxation of the human corpus cavernosum through nitrergic pathways involving the activation of ATP-dependent potassium channels (KATP). The maximal relaxation induced by yohimbine in the human corpus cavernosum strips pre-contracted with phenylephrine was 100±0% and only 30.5±5.0% when they were pre-contracted with 60-mM potassium (K+) solution. The maximal relaxation induced by yohimbine in phenylephrine pre-contracted tissues was significantly inhibited by tetrodotoxin, 1H-[1,2,4] oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) or 7-nitroindazole (43.6, 36.1 and 42.6%, respectively). Neither the combination charybdotoxin–apamin nor tetraethylammonium altered the response of the human corpora cavernosa strips to yohimbine. Nevertheless, glibenclamide decreased the maximum relaxant response to yohimbine by 29.8% (P<0.05; n=12). The results suggest that yohimbine relaxes the human corpus cavernosum by a non-adrenergic, non-cholinergic mechanism, probably activating the nitrergic-soluble guanylate cyclase (NO-sGc) pathway and KATP.
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Freitas, F., Nascimento, N., Cerqueira, J. et al. Yohimbine relaxes the human corpus cavernosum through a non-adrenergic mechanism involving the activation of K+ATP-dependent channels. Int J Impot Res 21, 356–361 (2009). https://doi.org/10.1038/ijir.2009.41
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DOI: https://doi.org/10.1038/ijir.2009.41
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