Endoneurial lipid composition of normal human sural nerve.

The endoneurial lipid composition was determined in 7 human sural nerves from subjects without known neurological disease. The nerves were morphologically normal, with myelinated fiber density of 7,710 +/- 1,210/mm2 (mean +/- SD). Endoneurium contained 30.7 +/- 1.5 mg total lipid per 100 mg of dry weight. Cholesterol was the predominant lipid (9.1 +/- 1.0 mg). Cholesterol ester was present only in very small quantities (0.2 +/- 0.1 mg). Cerebroside concentration was 4.5 +/- 0.3 mg, and sulfatide was 1.5 +/- 0.3 mg. The most abundant phospholipid was sphingomyelin (4.3 +/- 0.3 mg), followed by phosphatidylethanolamine (4.1 +/- 0.2 mg), phosphatidylcholine (3.8 +/- 0.2 mg), and phosphatidylinositol-phosphatidylserine (1.7 +/- 0.2 mg). Eighty-one percent of cerebroside nonhydroxy fatty acids were long chain (C20 to C26), and 67% were saturated. Technological advances now permit microchemical lipid analysis of human sural nerve biopsies in cases of neuropathy. When compared with our normative data, such studies may further the understanding of peripheral nerve disorders.