title: Improvement in relaxation response in corpus cavernosum from trained rats.
abstract: OBJECTIVE
  To evaluate the contractile and relaxing responses in rat corpus cavernosum (RCC) from rats after 8 weeks of run training, because erectile function is highly dependent on nitric oxide (NO) from nitrergic fibers or endothelium. Physical activity enhances NO production and improves endothelial function, with beneficial effects on cardiovascular disease.
  
  
  METHODS
  The training program consisted of 8 weeks of run training, 5 days/wk, and each session lasted 60 minutes. The RCC was isolated, and concentration-response curves to NO, acetylcholine, sodium nitroprusside, phenylephrine, and endothelin were obtained. The excitatory and inhibitory effects of electrical field stimulation (2 to 32 Hz) were also evaluated.
  
  
  RESULTS
  NO (0.1 to 100 microM) and sodium nitroprusside (0.01 to 1000 microM) produced a relaxing effect in RCC in a dose-dependent manner, with the maximal responses to NO (control 62% +/- 4%, trained 88% +/- 3%) and sodium nitroprusside (control 83% +/- 3%, trained 95% +/- 2%) significantly enhanced after 8 weeks of run training. However, acetylcholine-induced relaxations were not affected by exercise. Similarly, electrical field stimulation-induced relaxations were significantly increased in RCC from trained rats at 2 Hz (control 2.4% +/- 0.3%, trained 4.2% +/- 0.5%) and 4 Hz (control 5.3% +/- 1.2%, trained 12.5% +/- 1.7%). The contractile sensitivity of RCC to phenylephrine (0.01 to 100 microM) and endothelin (0.01 to 100 nM) was not modified by training exercise.
  
  
  CONCLUSIONS
  Our findings suggest that run training enhances functional responses in rat RCC that involves increases in the NO-cyclic guanosine monophosphate signaling pathway by endothelium-independent mechanisms that is not accompanied by changes in contractile sensitivity.
authors.affiliation: Department of Pharmacology, Faculty of Medical Sciences, UNICAMP, Campinas, São Paulo, Brazil.
authors.forename: Mário A
authors.initials: MA
authors.lastname: Claudino
authors.forename: Fernanda B M
authors.initials: FB
authors.lastname: Priviero
authors.forename: Cleber E
authors.initials: CE
authors.lastname: Teixeira
authors.forename: Gilberto
authors.initials: G
authors.lastname: de Nucci
authors.forename: Edson
authors.initials: E
authors.lastname: Antunes
authors.forename: Angelina
authors.initials: A
authors.lastname: Zanesco
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D016232:Endothelins / Q000494:pharmacology; D045462:Endothelium-Dependent Relaxing Factors / Q000494:pharmacology; D008297:Male; D009569:Nitric Oxide / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D010413:Penis / Q000187:drug effects / Q000502:physiology*; D010656:Phenylephrine / Q000494:pharmacology; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D016232:Endothelins; D045462:Endothelium-Dependent Relaxing Factors; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D009599:Nitroprusside; D010656:Phenylephrine; D009569:Nitric Oxide; D000109:Acetylcholine