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2006, Number 1

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Gac Med Mex 2006; 142 (1)

Testosterone inhibits the contractile responses to phenilephrine associated with the release of intracellular calcium in rat aorta.

Castillo C, Castillo EF, López J, López RM

Language: Spanish
References: 30
Page: 1-8
PDF size: 145.95 Kb.


ABSTRACT

Using endothelium-denuded rat aortic rings incubated in Ca2+-free solution, we assessed the ability of testosterone to influence the contractile effect of phenylephrine, and the increase in resting tone (IRT) associated with Ca2+ ability to cross the plasma membrane. The addition of testosterone [10-5–10-4 M] 5 min before phenylephrine [10-6 M], inhibited both phenylephrine-induced contraction and IRT. These changes were not affected by cycloheximide (10-5 M; a protein synthesis inhibitor of), flutamide (10-5 M; an androgenic receptor antagonist), or by adding aminoglutethimide (10-5 M; an aromatase inhibitor). Testosterone also blocked the contractile response to serotonin [10-5 M] but not to caffeine [10-2 M]. On the other hand, testosterone inhibited the contractile responses to cyclopiazonic acid (10-6 M; a selective Ca2+-ATPase inhibitor) or ryanodine (10-5 M; an activator of sarcoplasmic reticulum Ca2+-release channels) associated with capacitative Ca2+ influx through non-L-type Ca2+ channels. These data suggest that by acting on the cellular membrane, testosterone interferes with the signal transduction pathway of Gq-11 protein-coupled receptors, and inhibits capacitative Ca2+ influx through both L-type and non-L-type Ca2+ channels. These effects are non-genomic, non-mediated by the intracellular androgen receptor, and not due to the conversion of testosterone to estrogens.


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