Methods of investigation of the nervous system: the problem of the permeability of the frog sciatic nerve sheath: submitted for the Ellis Prize in Physiology

Abstract

1. Previous evidence on tine question of the permeability of the frog sciatic nerve sheath is reviewed.2. Methods used by previous investigators are also reviewed.3. A perfusion method for the study of the behaviour of the intact frog sciatic nerve, with Dextran and gelatin perfusates and a non-perfused symmetrical control is described.4. Na free perfusates block conduction in as little as 6.5 minutes.5. Na free, 0.12 M KCl and 0.10 M BaCl₂ solutions produce block very much more rapidly in perfused than in non-perfused nerves.6. 10 vol.% acetone and 10 vol.% ethyl alcohol block perfused and non-perfused nerves with about equal rapidity.7. It is suggested that the results obtained are good evidence that the frog sciatic nerve sheath is an effective barrier to the diffusion of electrolytes.