Intestinal ischemia-induced changes in the activity of NADPH-d and energy metabolism enzymes in rat myenteric and splanchnic plexus

The changes in the activity of NADPH-d and energy metabolism enzymes, lactate dehydrogenase (LDG) and succinate dehydrogenase (SDG), in the neurons of splanchnic and myenteric plexus (SP and MP, respectively), induced by 1-h-long ischemization of a part of the small intestine, were studied using cytophotometric technique; the measurements were performed under conditions when synthesis of nitric oxide (NO) was either blocked or activated. The activity of NADPH-d, SDG, and LDG in MP neurons was shown to be enhanced by ischemia. In SP neurons, the LDG activity increased, while the NADPH-d and SDG activities did not change. The blockade of NO synthesis with nitro-L-arginine methyl ester was followed by a decrease in the NADPH-d level in SP and MP neurons, but was maintained at a level lower than the control one during ischemia. Administration of L-arginine, the NO precursor, increased NADPH-d activity in MP and SP neurons, while at ischemization of the intestine this activity remained at a level higher than in the control. It is concluded that NO-ergic mechanisms (mostly at the MP level) are significantly involved in regulation of the functions of the small intestine in ischemia.