Endoneurial ATPase activity in Tangier disease and other peripheral neuropathies.

Endoneurial sodium, potassium adenosine triphosphatase (Na+,K+-ATPase) and Mg2+-ATPase activities were determined in routine sural nerve biopsies from patients being evaluated for peripheral neuropathy. A significant reduction of endoneurial Na+,K+-ATPase and Mg2+-ATPase activities was shown in six sural nerve biopsies from patients with Tangier disease complicated by mononeuropathy multiplex or progressive axonal neuropathy. Peripheral nerve ATPase activities did not correlate with myelinated or unmyelinated nerve fiber densities in these biopsies. Other peripheral neuronal disorders with reduced endoneurial Na+,K+-ATPase and Mg2+-ATPase activities included severe vasculitic neuropathy, diabetic neuropathy, tomaculous neuropathy, and motoneuron disease. Such reduced levels of ATPase activity in peripheral nerve may relate to altered endoneurial lipid metabolism and impaired axoplasmic flow.