Sodium channel activity of lobster nerve membrane treated with purified phospholipase A2.

Sodium channel activity was determined by measuring the veratridine-tetrodotoxin-sensitive sodium influx in reconstituted vesicles prepared from lobster nerve membrane and soybean lipids. The sodium channel activity was abolished by treatment of membranes, prior to reconstitution, with purified phospholipase A2. When the treatment with phospholipase A2 was carried out in the presence of bovine serum albumin the channel activity was fully preserved. Electron microscopy revealed that the normal vesicular appearance of the membranes was changed to an amorphous mass by treatment of the membranes with enzyme alone. A population of preserved vesicular structures was observed when bovine serum albumin was present during the enzyme treatment. Analysis of the membrane components indicate that there is no relationship between phospholipid composition and sodium channel activity.