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Nitric oxide-mediated corpus cavernosal smooth muscle relaxation is impaired in ageing and diabetes

J J Cartledge1, I Eardley, J F Morrison

  • 1Pyrah Department of Urology, St James's University Hospital, Leeds, UK. j.cartledge@ukgateway.net

BJU International
|March 17, 2001
PubMed

Insights

Diabetes significantly impairs nitric oxide (NO)-mediated smooth muscle relaxation in rat penile tissue. This dysfunction is not due to superoxide anions but may involve cholesterol or advanced glycation end products.

Area of Science:

  • Urology
  • Physiology
  • Endocrinology

Background:

  • Diabetes mellitus is associated with erectile dysfunction.
  • Nitric oxide (NO) mediates smooth muscle relaxation crucial for penile erection.
  • Previous studies suggested impaired NO-mediated relaxation in diabetic cavernosal tissue due to superoxide anions.

Purpose of the Study:

  • To investigate the impact of diabetes on NO-mediated relaxation in rat penile cavernosal smooth muscle.
  • To determine the mechanisms underlying this impairment, specifically examining the roles of NO availability, superoxide anions, and constrictor prostanoids.

Main Methods:

  • Diabetes was induced in male Wistar rats for 8 weeks.
  • Cavernosal smooth muscle strips were contracted and then relaxed using acetylcholine, electrical field stimulation (EFS), or sodium nitroprusside (SNP).
  • Relaxation responses were assessed in the presence of L-arginine, indomethacin, or superoxide dismutase (SOD).

Main Results:

  • Diabetes significantly impaired relaxation responses to acetylcholine and EFS but not SNP.
  • Neither L-arginine, indomethacin, nor SOD significantly reversed the diabetic impairment.
  • Aging also caused a significant impairment in EFS-mediated relaxation.

Conclusions:

  • Diabetes in rats leads to impaired endothelial and neuronal NO-mediated relaxation of penile smooth muscle in vitro.
  • The impairment is not explained by altered intracellular NO action, NO availability, superoxide inactivation of NO, or constrictor prostanoids.
  • Cholesterol or advanced glycation end products are potential contributors to diabetes-induced penile smooth muscle dysfunction.
Abstract

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