To test the hypothesis that increased endoneurial fluid pressure (EFP) causes a reduction in nerve blood flow (NBF) in the vasa nervorum, we adapted a noninvasive method for measurement of nerve blood flow which was originally developed for measurement of local cerebral blood flow. This technique measures tissue distribution of the radioisotope, 14C-iodoantipyrine, and was used to compare NBF in sciatic nerves of rats with increased EFP induced by feeding them hexachlorophene (HCP), a neurotoxin which causes edema exclusively to the nervous system and confined to the myelin sheath. Elevation of interstitial fluid pressure in peripheral nerves from control values of 2.0 plusmn; 1.0 cm H2O to over approximately 6 cm H2O was associated with a statistically significant reduction in nerve blood flow from 14.8 plusmn; 5.9 to 7.8 plusmn; 2.5 ml/100 g of tissue/minute (min). These results support the hypothesis that increased endoneurial fluid pressure exacerbates the neuropathy by diminishing local blood flow.
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