Gating charge immobilization and sodium current inactivation in internally perfused crayfish axons.

摘要: The sodium permeability in nerve is regulated by two gating processes, activation and inactivation1. Their relationship to one another has been described as ‘independent’1 or ‘coupled’2,3. An independent model, the Hodgkin Huxley formulation, makes testable predictions regarding current. First, inactivation voltage sensitive, it requires its own sensor might be expected generate Second, current associated with should unaffected inactivation. Although charge movement well characterized4, no described. Instead, depolarizations long enough produce were found diminish channel closing5. Inactivation temporarily immobilized a substantial fraction of charge. These observations suit coupled model which gains dependence coupling activation3, may turn influence activation. However, relative time course development immobilization (τimmob) was same3, same some ranges6 slower than that for (τinact). In crayfish axons roughly five times faster squid, providing an interesting opportunity compare immobilization. Further, so rapid easily visible. No τimmob equals τinact.