Noncholinergic penile erection in mice lacking the gene for endothelial nitric oxide synthase

A. L. Burnett, A. G. Chang, J. K. Crone, P. L. Huang, S. F. Sezen

Research output: Contribution to journalArticlepeer-review

67 Scopus citations


With the current understanding that nitric oxide (NO) mediates penile erection, the endothelial isoform of NO synthase (eNOS) has been implicated in this function. We undertook this study applying transgenic mice with targeted deletion of the eNOS gene (eNOS-/- mice) as an experimental approach to evaluate the importance of eNOS in cholinergically stimulated erectile function in vivo. Combined pharmacostimulation with intracavernosal carbachol (3 ng) administration and submaximal cavernous nerve (CN) electrical stimulation (16 Hz, 5 millisecond, 1 V) simultaneous with intracavernosal pressure (ICP) monitoring, and both biochemical assay of NO synthase activity and Western blot analysis of eNOS protein content in penile tissue, were performed on eNOS-/- mice and wild-type controls. Combined intracavernosal carbachol administration and submaximal CN electrical stimulation raised the recorded ICP, elicited by CN electrical stimulation alone in wild-type mice (from 35.7 ± 2.7 to 48.1 = 5.5 mm Hg, P < .05) but not in eNOS-/- mice (from 54.9 ± 6.3 to 51.0 ± 9.5 mm Hg, not significant [NS]). Pretreatment with the nonselective nitric oxide synthase inhibitor nitro-L-arginine methyl ester (L-NAME; 100 mg intracavernosally) blocked electrically stimulated ICP responses in eNOS-/- mice to baseline levels (37.8 ± 4.4 vs 12.7 ± 4.0 mm Hg, P < .05). In penes of eNOS-/- mice, approximately 60% NO synthase activity of wildtype penis levels was retained (NS), and eNOS protein was absent. We concluded that eNOS-/- mice preserve erectile function on the basis of a noncholinergic but NO-dependent mechanism and that eNOS physiologically mediates penile erection under cholinergic stimulation.

Original languageEnglish (US)
Pages (from-to)92-97
Number of pages6
JournalJournal of andrology
Issue number1
StatePublished - Jan 1 2002


  • Carbachol
  • Cholinergic
  • Endothelium
  • Penis
  • Transgenic mice

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Reproductive Medicine
  • Endocrinology
  • Urology


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