The blood-nerve barrier is rich in glucose transporter

The glucose transporter of the facilitated diffusion type has been localized in sections of innervated rat diaphragm muscle and sciatic nerve by immunofluorescence, using affinity-purified antibodies against both the entire transporter and the carboxy-terminal peptide. In both tissues the transporter was very abundant in the perineurial sheath of cells surrounding the nerve fibres. The transporter also appeared to be abundant in the endoneurial blood vessels of the sciatic nerve. The identity of the antigen as the glucose transporter was established by extracting sciatic nerve with sodium dodecylsulphate and immunoblotting the extract. A single reactive polypeptide with the expected molecular weight of 55,000 was found. The high concentration of glucose transporter in the cells of the blood-nerve barrier presumably ensures an adequate supply of glucose to the nerve fibres.