The effects of lithium and sodium on the potassium conductance of snail neurones.

1. The iontophoretic injection of lithium into snail neurones reversibly increased the resting relative potassium permeability (PK). 2. Long exposures to snail Ringer containing 25 mM-Li and correspondingly reduced Na also caused an increase in PK. This did not occur with Ringer in which the same reduction of Na was made by replacing it with Tris. 3. Replacement of part of the Ringer Na by either Li or Tris led to proportional decreases in internal Na. 4. Injecting large quantities of Na into ouabain-treated cells caused effects similar to those of Li injection. Without ouabain, Na injection stimulated the electrogenic Na pump. 5. A number of tests failed to produce any clear evidence that intracellular Ca was involved in the response to Li.