Neurovascular effects of L-carnitine treatment in diabetic rats.

The aims were to ascertain whether L-carnitine could prevent nerve blood flow and conduction deficits in 1-month diabetic rats and to examine potential neurovascular mechanisms using co-treatment with the nitric oxide synthase inhibitor, NG-nitro-L-arginine. A 19.8% diabetic deficit in sciatic motor conduction velocity was 57.4% attenuated by L-carnitine treatment. Similarly, a 47.7% reduction in sciatic nutritive (capillary) endoneurial blood flow was 48.6% blocked by L-carnitine. Joint treatment with NG-nitro-L-arginine completely abolished the effects on nerve conduction and nutritive flow. However, L-carnitine treatment did not alter a 50.8% diabetic deficit in total sciatic endoneurial flow, which was further depressed (61%) by NG-nitro-L-arginine co-treatment. Thus, the effect of L-carnitine on nerve conduction in diabetic rats depends on changes in the endoneurial perfusion pattern by an action that may involve the nitric oxide system of vasa nervorum.