Nitric oxide modulates the gastrointestinal plasma extravasation following intraabdominal surgical manipulation in rats.

The actions of nitric oxide (NO) on gastrointestinal plasma loss, assessed by the leakage of [125I]human serum albumin, provoked by intraabdominal surgery and organ manipulation has been investigated in pentobarbitone-anaesthesized rats. Gentle manipulation (3 min) of the stomach or the small intestine following laparotomy leads to an increase in albumin extravasation in the stomach, duodenum, jejunum and colon over 1 h. Administration of the NO synthase inhibitors, N(G)-nitro-L-arginine methyl ester (1-5 mg kg(-1), s.c.) and N(G)-monomethyl-L-arginine (12.5-50 mg kg(-1), s.c.), provoked a further substantial elevation of gastrointestinal albumin extravasation in the surgically manipulated rat, but not in control rats. This effect could be prevented by the pretreatment (15 min) with L-arginine (300 mg kg(-1), s.c.) or by the concurrent infusion of the NO donor, S-nitroso-glutathione (5 microg kg(-1) min(-1), i.v.). Endogenous NO, most likely formed by endothelial NO synthase, thus appears to maintain microvascular integrity during surgery and organ manipulation of the gastrointestinal tract.