title: Compartments and barriers in the sciatic nerve of the rabbit.
abstract: Near constant concentration of various radioactively labelled polar nonelectrolytes were maintained in the blood plasma of renal ligated rabbits. The uptake of [14C]urea, [51Cr]EDTA and [14C]inulin into sciatic nerve was interpreted in terms of a two-compartment model. There was a rapidly equilibrating space representing about 20% of the tissue weight which is almost certainly the interstitial fluid of the epineurium and outer layers of the perineurium. Urea penetrated the blood-nerve barrier at a similar rate to the entry of this compound into brain. Sucrose, chromium-EDTA and sulphate passed into the true interstitial fluid approaching a total volume of distribution of about 36% of the tissue weight at 6-8 h. Since movement of these 3 solutes is severely restricted by the blood-barrier, the blood-nerve barrier in the  rabbit must contain channels of greater than 1 nm which are not present in the developed blood-brain barrier. Uptake of [3H]3-O-methylglucose into nerve was examined but the results did not give a conclusive answer to the question of whether there is specific transport of sugars at the blood-nerve barrier. The wet nerve contained (in mmole/kg) sodium 74.3; potassium 42.6 and chloride 48.8. Water was 64.6 ml/100 g. Intracellular electrolyte concentrations were estimated. Approximately 30% of the total sodium content cannot be accounted for as being free in the interstitial fluid at a Gibbs-Donnan distribution with plasma. Analysis of metabolically poisoned nerves which have equilibrated with salt solution in vitro suggests that negatively charged polyelectrolyte molecules retain about 14 mmole of sodium/kg wet normal nerve.
mesh_terms: D000818:Animals; D050260:Carbohydrate Metabolism; D002712:Chlorides / Q000097:blood / Q000378:metabolism; D003486:Cyanides; D005110:Extracellular Space / Q000378:metabolism; D005260:Female; D007444:Inulin / Q000378:metabolism*; D007461:Iodoacetates / Q000494:pharmacology; D008297:Male; D008757:Methylglucosides / Q000378:metabolism; D008970:Molecular Weight; D011188:Potassium / Q000378:metabolism; D011817:Rabbits; D012584:Sciatic Nerve / Q000187:drug effects / Q000378:metabolism*; D012964:Sodium / Q000097:blood / Q000378:metabolism; D013395:Sucrose / Q000378:metabolism; D013431:Sulfates / Q000378:metabolism; D014508:Urea / Q000378:metabolism*; D014867:Water / Q000378:metabolism
chemical_list: D002712:Chlorides; D003486:Cyanides; D007461:Iodoacetates; D008757:Methylglucosides; D013431:Sulfates; D014867:Water; D013395:Sucrose; D014508:Urea; D007444:Inulin; D012964:Sodium; D011188:Potassium