Ischemic conduction failure and energy metabolism in experimental diabetic neuropathy

We examined the effect of ischemia on nerve conduction in experimental diabetic neuropathy (EDN) and related electrophysiological changes to nerve adenosine triphosphate (ATP), creatine phosphate (CP), and lactate under anoxic conditions. Rats rendered diabetic with streptozotocin had a resistance to ischemic conduction block (RICB). Caudal nerve action potential (NAP) was well maintained for 10 min in controls and for 15 min in EDN, after which time NAP declined in both groups but more rapidly in normal rats. Time to 50% reduction in nerve ATP and CP was 10 and 3 min, respectively, in controls and delayed to 20 and 8 min in EDN. Rate of utilization of high-energy phosphate (approximately P) was linear for 5 min in controls to be followed by a progressive decline. In EDN rate of utilization of approximately P was linear to 15 min to be followed by a more gradual decline than in normal nerves. These findings suggest that the maintenance of nerve transmission in anoxic-ischemic states depends on anaerobic metabolism and that RICB in EDN is due in part to the ability of diabetic nerves to maintain a higher level of anaerobic glycolysis and for a longer time than normal nerves.