Role of NK2 receptors in gastric barosensitivity and in experimental ileusin rats

This study was performed to evaluate the role of tachykinin NK2 receptors i n gastric barosensitivity and in postsurgical intestinal atony, using a sel ective NK2 antagonist (MEN 11420). Gastric distensions were performed in ra ts equipped with a gastric balloon and electrodes implanted in the neck mus cles. Ileus was produced by laparotomy and caecum palpation in rats previou sly prepared with electrodes implanted on the proximal jejunum. Fifteen min utes before gastric distension or laparotomy, the animals received MEN 1142 0 (10, 100 or 200 mug kg(-1) intravenously) or saline. The first distending pressure to increase the integrated neck electromyogram > 100% was conside red the pain threshold. MEN 11420 (100 mug kg(-1)) increased significantly pain threshold (20.5 +/- 1.2 vs. 17.0 +/- 0.8 mm Hg) but did not modify gas tric volumes at the three doses tested. Abdominal surgery was followed by a total inhibition of jejunal spiking activity lasting 80.4 +/- 18.7 min. ME N 11420 (10 and 100 mug kg(-1)) shortened the duration of motor inhibition by 36 and 39%, and induced a premature recovery of the phase III of migrati ng myoelectric complex at the lowest dose tested (130 +/- 32 vs. 192 +/- 28 min). We conclude that NK2 receptors, probably located on afferent fibres, are involved in gastric barosensitivity and in postsurgical intestinal ato ny.