Effect of ileo-jejunal transposition on ileal longitudinal smooth muscle contractility in vitro in rats.

The aim of the present paper was to study the effects of ileo-jejunal transposition (IJT) on ileal contractile activity in vitro in rats. Male Sprague-Dawley rats were divided into three groups: control, IJT, and sham. In rats with IJT, the distal ileum was interposed isoperistaltically into the proximal jejunum. The jejunoileum was transected and anastomosed at three sites in the sham group. Rats were sacrificed 17-20 weeks postoperatively and the ileal segment was removed. Isometric contractile activity of the isolated ileal longitudinal muscle was measured in tissue chambers. Spontaneous contractile activity was decreased in the IJT group (0.16 +/- 0.03 g/min per mg tissue) as compared with the control group (0.25 +/- 0.02 g/min per mg tissue, p < 0.05). The motor response to cholinergic agonist bethanechol in the IJT group was greater than in the control group above 10(-6) M dosage. The dose-response curves to adrenergic agonist norepinephrine did not differ between groups. A nitric oxide synthase inhibitor reversed electrical field stimulation-induced inhibition of spontaneous activity in all groups. These results indicate that the response to bethanechol in the IJT group was enhanced in rat ileal longitudinal smooth muscle and this may be an adaptive response to compensate for decreased spontaneous contractile activity.