Chronic Ethanol Consumption Induces Cavernosal Smooth Muscle Dysfunction in Rats - 06/08/11
Reprint requests: Luis Fernando Tirapelli, Ph.D., Department of Surgery and Anatomy, University of São Paulo, Faculty of Medicine of Ribeirão Preto, Avenida Bandeirantes 3900, 14,049-900, Ribeirão Preto, SP, BrazilRésumé |
Objectives |
To investigate the effects of chronic ethanol consumption on nitric oxide (NO)–mediated relaxation in rat cavernosal smooth muscle (CSM).
Methods |
Male wistar rats were divided into 2 groups: control and ethanol. CSM obtained from both groups were mounted in organ chambers for measurement of isometric tension. Contraction of the strips was induced by electrical field stimulation (EFS, 1-32 Hertz) and phenylephrine. We also evaluated the effect of ethanol consumption on the relaxation induced by acetylcholine (0.01-1000 μmol L−1), sodium nitroprusside (SNP, 0.01-1000 μmol L−1), or EFS (1-32 Hz) in strips precontracted with phenylephrine (10 μmol L−1). Blood ethanol, serum testosterone levels, and basal nitrate generation were determined. Immunoexpression of endothelial NO synthase (eNOS) and inducible NO synthase (iNOS) was also accessed.
Results |
Ethanol intake for 4 weeks significantly increased noradrenergic nerve-mediated contractions of CSM in response to EFS. The endothelium-dependent relaxation induced by acetylcholine decreased after the ethanol treatment. Ethanol consumption decreased serum testosterone levels but did not affect the nitrate levels on rat CSM. The mRNA and protein levels for eNOS and iNOS receptors were increased in CSM from ethanol-treated rats.
Conclusions |
Ethanol consumption reduces endothelium-dependent relaxation induced by acetylcholine, but does not affect SNP or EFS-induced relaxation, suggesting that ethanol disrupts the endothelial function. Despite the overexpression of eNOS and iNOS in ethanol-treated rats, the impaired relaxation induced by acetylcholine may suggest that chronic ethanol consumption induces endothelial dysfunction.
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| This work was supported by CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior). |
Vol 74 - N° 6
P. 1250-1256 - décembre 2009 Retour au numéro
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