Long-term nitric oxide deficiency causes muscarinic supersensitivity and reduces beta(3)-adrenoceptor-mediated relaxation, causing rat detrusor overactivity

Br J Pharmacol. 2008 Apr;153(8):1659-68. doi: 10.1038/bjp.2008.39. Epub 2008 Feb 25.


Background and purpose: Overactive bladder is a complex and widely prevalent condition, but little is known about its physiopathology. We have carried out morphological, biochemical and functional assays to investigate the effects of long-term nitric oxide (NO) deficiency on muscarinic receptor and beta-adrenoceptor modulation leading to overactivity of rat detrusor muscle.

Experimental approach: Male Wistar rats received N(omega)-nitro-L-arginine methyl ester (L-NAME) in drinking water for 7-30 days. Functional responses to muscarinic and beta-adrenoceptor agonists were measured in detrusor smooth muscle (DSM) strips in Krebs-Henseleit solution. Measurements of [(3)H]inositol phosphate, NO synthase (NOS) activity, [(3)H]quinuclidinyl benzilate ([(3)H]QNB) binding and bladder morphology were also performed.

Key results: Long-term L-NAME treatment significantly increased carbachol-induced DSM contractile responses after 15 and 30 days; relaxing responses to the beta(3)-adrenoceptor agonist BRL 37-344 were significantly reduced at 30 days. Constitutive NOS activity in bladder was reduced by 86% after 7 days and maintained up to 30 days of L-NAME treatment. Carbachol increased sixfold the [(3)H]inositol phosphate in bladder tissue from rats treated with L-NAME. [(3)H]QNB was bound with an apparent K(D) twofold higher in bladder membranes after L-NAME treatment compared with that in control. No morphological alterations in DSM were found.

Conclusions and implications: Long-term NO deficiency increased rat DSM contractile responses to a muscarinic agonist, accompanied by significantly enhanced K(D) values for muscarinic receptors and [(3)H]inositol phosphate accumulation in bladder. This supersensitivity for muscarinic agonists along with reductions of beta(3)-adrenoceptor-mediated relaxations indicated that overactive DSM resulted from chronic NO deficiency.

MeSH terms

  • Adrenergic beta-3 Receptor Agonists
  • Adrenergic beta-Agonists / pharmacology
  • Animals
  • Carbachol / pharmacology
  • Inositol Phosphates / metabolism
  • Male
  • Muscarinic Agonists / pharmacology
  • Muscle Contraction / drug effects*
  • Muscle, Smooth / metabolism
  • NG-Nitroarginine Methyl Ester
  • Nitric Oxide / deficiency*
  • Nitric Oxide Synthase / metabolism
  • Rats
  • Rats, Wistar
  • Receptors, Adrenergic, beta-3 / metabolism*
  • Receptors, Muscarinic / drug effects
  • Receptors, Muscarinic / metabolism*
  • Urinary Bladder / metabolism
  • Urinary Bladder / physiopathology
  • Urinary Bladder, Overactive / physiopathology*


  • Adrenergic beta-3 Receptor Agonists
  • Adrenergic beta-Agonists
  • Inositol Phosphates
  • Muscarinic Agonists
  • Receptors, Adrenergic, beta-3
  • Receptors, Muscarinic
  • Nitric Oxide
  • Carbachol
  • Nitric Oxide Synthase
  • NG-Nitroarginine Methyl Ester