Nitric oxide pathways in circular muscle of the rat jejunum before and after small bowel transplantation

Previous studies suggest that nitric oxide synthase is upregulated after sm all bowel transplantation which may have implications in enteric dysfunctio n after small bowel transplantation. The aim of this study was to determine the role of nitric oxide in nonadrenergic, noncholinergic inhibitory funct ion after small bowel transplantation in rat jejunal circular muscle. The f ollowing four groups of rats (n = greater than or equal to 8 mts per group) were studied: Neurally intact control animals; 1 week after anesthesia and sham celiotomy, and either 1 week or 8 weeks after isogeneic, orthotopic s mall bowel transplantation. Full-thickness jejunal circular muscle strips w ere evaluated under isometric conditions for spontaneous contractile activi ty, response to electrical field stimulation, and effects of exogenous nitr ic oxide and nitric oxide antagonists. Spontaneous activity did not differ among groups. Electrical field stimulation inhibited activity similarly in all groups. Exogenous nitric oxide, n(G)-monomethy L-arginine monoacetate s alt (a nitric oxide synthase inhibitor), and methylene blue (cGMP antagonis t) had no effect on spontaneous activity Neither nitric oxide antagonist al tered the inhibitory response to neural excitation by electrical field stim ulation in any group. Nitric oxide, a known inhibitory neurotransmitter in other gut smooth muscle, has no apparent role in rat jejunal circular muscl e before or after small bowel transplantation.