Sodium nitroprusside regulates the relaxation of the longitudinal muscle in the gut

Nitric oxide (NO) has been shown to mediate nonadrenergic-noncholinergic relaxation in gastrointestinal (GI) smooth muscle cells. As GI smooth muscles relaxations are partly dependent on NO, we decided to investigate the effect of sodium nitroprusside (SNP) on the longitudinal muscle contraction of...

Full description

Saved in:

Bibliographic Details
Published in:	Pharmazie Vol. 63; no. 2; p. 151
Main Authors:	Tepavcević, S N, Isenović, E R, Varagić, V M, Milovanović, S R
Format:	Journal Article
Language:	English
Published:	Germany 01-02-2008
Subjects:	Animals Arginine - pharmacology Female Free Radical Scavengers - pharmacology Gastrointestinal Tract - drug effects Guanylate Cyclase - metabolism Guinea Pigs Ileum - drug effects In Vitro Techniques Male Muscle Relaxation - drug effects Muscle, Smooth - drug effects Nitroprusside - pharmacology Solutions Superoxide Dismutase - pharmacology Vasodilator Agents - pharmacology
Online Access:	Get more information
Tags:	Add Tag No Tags, Be the first to tag this record!

Description
Summary:	Nitric oxide (NO) has been shown to mediate nonadrenergic-noncholinergic relaxation in gastrointestinal (GI) smooth muscle cells. As GI smooth muscles relaxations are partly dependent on NO, we decided to investigate the effect of sodium nitroprusside (SNP) on the longitudinal muscle contraction of the isolated guinea pig ileum. Increasing concentrations of SNP (10(-10)M, 10(-9)M, 10(-8)M, 10(-7)M, 10(-6)M and 10(-5)M) reduced ileum contractions stimulated by electrical stimulation (ES) (8-76%; p < 0.05) and by acetylcholine (Ach) (23-62%; p < 0.05) significantly and in a concentration-dependent manner. Furthermore, treatment with an inhibitor of the soluble guanylate cyclase, methylene blue (10 mM), antagonized significantly the relaxing effect of SNP (0-39%; p < 0.05, p < 0.01, p < 0.001 for ES- and 4-27%; p < 0.05 for Ach-induced contractions). The results show that treatment with 1 microM manganese-containing superoxide dismutase (MnSOD) and 10 microM L-arginine (L-arg) caused a significant decrease in SNP induced relaxations (6-55%; p < 0.05, p < 0.001 and 2-46%; p < 0.05, p < 0.01 for ES- and 15-28%; p < 0.05, p < 0.01, p < 0.001 and 12-32%; p < 0.05, p < 0.01 for Ach-induced contractions, respectively). In conclusion, our data suggest that SNP, which releases NO, is able to depress longitudinal muscle contraction of the isolated guinea pig ileum, suggesting that exogenous application of NO inhibits intestinal contractions of smooth muscle cells and that cGMP mediates the response to NO. In addition, MnSOD and L-arg decreased the relaxing effect of SNP on the isolated ileum of the guinea pig.
ISSN:	0031-7144
DOI:	10.1691/ph.2008.7649