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Run training ameliorates the established erectile dysfunction in rats under long-term nitric oxide (NO) blockade
© Claudino et al; licensee BioMed Central Ltd. 2007
Published: 25 July 2007
Stimulation of nitrergic neurons and endothelial cells in the erectile tissue results in release of NO that diffuse to surrounding smooth muscle cells where it activates the soluble guanylate cyclase (sGC), facilitating the conversion of GTP to cGMP. This second messenger diminishes the intracellular levels of calcium thereby causing penile smooth muscle relaxation and penile erection . Epidemiological studies have shown a strong association between erectile dysfunction (ED) and arterial hypertension , where the deficiency of the NO-cGMP pathway seems to greatly contribute to such association . Regular physical exercise has been shown to increase the NO production thus ameliorating cardiovascular diseases [2, 4]. Recently, we have shown that prior physical conditioning improves the erectile function in normotensive rats  and prevents the impaired corpus cavernosum relaxation secondary to chronic NO blockade in rats .
The aim of this work was to evaluate whether regular run training restores the established ED in made hypertensive by chronic treatment with the NO synthesis inhibitor L-NAME.
Wistar rats were divided into control sedentary (C-SD), control trained (C-TR), L-NAME sedentary (LN-SD) and L-NAME trained (LN-TR) groups. Rats were treated with L-NAME (10 mg/rat/day) or tap water alone for 8 weeks. The run training program initiated after 4 weeks of L-NAME treatment. It consisted in 4 weeks in a treadmill, 5 days/week, each session lasting 60 min. The nitregic relaxing responses were evaluated by both electrical field stimulation (EFS) of corpus cavernosum in vitro and measurement of intracavernosal pressure (ICP) in response to electrical stimulation of the cavernous nerve (in vivo experiments). The plasma levels of nitrite/nitrate (NOx) were also measured.
Experimental values were obtained from control sedentary (C-SD), control trained (C-TR), L-NAME sedentary (LN-SD) and L-NAME trained (LN-TR) animals. Data are mean ± S.E.M of 4–8 experiments. *P < 0.05 compared to C-SD group; #P < 0.05 compared to LN-SD group; †P < 0.05 compared to C-TR.
Our findings show that run training significantly reverses the established erectile dysfunction due to impairment of the NO-GMPc signalling pathway in rats.
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