title: Nitric oxide mediates neurogenic relaxation induced in rabbit cavernous smooth muscle by electric field stimulation.
abstract: We investigated the relaxant effect of electric field stimulation (EFS) on rabbit cavernous smooth muscle strips in vitro precontracted by phenylephrine. Effects of EFS were monitored alone, and following muscarinic receptor blockade, and inhibition of nitric oxide (NO) formation by L-N-monomethylarginine (L-NMMA) or by L-N-nitroarginine (L-NOARG). Atropine only slightly reduced the relaxant effect of EFS to 89.0 +/- 6.1 percent. Additional application of L-NMMA further reduced the relaxant effect to 37.3 +/- 15.3 percent. Substitution of L-NOARG for L-NMMA led to a more pronounced inhibition of relaxant effects to 16.2 +/- 8.7 percent. The results indicate that neurogenically induced relaxation of rabbit cavernous smooth muscle is mediated mainly by NO formation and argue against a substantial role of relaxing peptidergic neurotransmitters, such as vasoactive intestinal polypeptide and calcitonin-gene-related peptide, in penile erection.
authors.affiliation: Department of Urology, Klinikum Steglitz, Free University of Berlin, Germany.
authors.forename: H H
authors.initials: HH
authors.lastname: Knispel
authors.forename: C
authors.initials: C
authors.lastname: Goessl
authors.forename: R
authors.initials: R
authors.lastname: Beckmann
mesh_terms: D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D004558:Electric Stimulation; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D009569:Nitric Oxide / Q000494:pharmacology*; D019335:Nitroarginine; D010410:Penile Erection / Q000187:drug effects / Q000502:physiology*; D010413:Penis / Q000294:innervation / Q000502:physiology*; D010656:Phenylephrine / Q000494:pharmacology; D011817:Rabbits; D019323:omega-N-Methylarginine
chemical_list: D010656:Phenylephrine; D019335:Nitroarginine; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D001120:Arginine