Essential role of nitric oxide in descending inhibition in the rat proximal colon

Biochem Biophys Res Commun. 1990 Nov 15;172(3):1400-6. doi: 10.1016/0006-291x(90)91605-r.


Possible mediators of descending inhibition in the rat proximal colon were studied. Localized distension with a small balloon caused relaxation of the circular muscle on the anal side of the distended region. This relaxation was still observed after the colonic segment had been desensitized to ATP, neurotensin and vasoactive intestinal peptide, so these compounds seem unlikely to mediate descending inhibition. Nitro-arginine inhibited the relaxation induced by the distension, and L-arginine counteracted the effect of nitro-arginine. Nitric oxide, isoamylnitrate and sodium nitroprusside caused relaxation. These results strongly suggest an essential role of nitric oxide in descending relaxation in the rat proximal colon.

MeSH terms

  • Adenosine Triphosphate / pharmacology
  • Animals
  • Arginine / analogs & derivatives
  • Arginine / pharmacology
  • Colon / drug effects*
  • Colon / physiology
  • Male
  • Muscle Relaxation / drug effects*
  • Neurotensin / pharmacology
  • Nitrates / pharmacology
  • Nitric Oxide / pharmacology*
  • Nitroarginine
  • Nitroprusside / pharmacology
  • Pentanols / pharmacology
  • Rats
  • Rats, Inbred Strains
  • Vasoactive Intestinal Peptide / pharmacology


  • Nitrates
  • Pentanols
  • Nitroprusside
  • Nitroarginine
  • Nitric Oxide
  • Vasoactive Intestinal Peptide
  • Neurotensin
  • Adenosine Triphosphate
  • Arginine
  • amyl nitrate