Effect of lithium and sodium valproate ions on resting membrane potentials in neurons: an hypothesis.

In an attempt to understand the therapeutic effects of lithium and sodium valproate in stabilizing the moods in manic depressive illness, the well-known Goldman-Hodgkin-Katz (G-H-K) equation is modified to include a fourth ion, such as a lithium ion or a sodium ion. The modified G-H-K equation is used to calculate the resting membrane potential in neurons. These calculations show that the resting membrane potential is depolarized depending upon the relative concentration of the lithium ion and upon its relative permeability. These calculations suggest that the resting membrane potential may be hyperpolarized in bipolar patients before treatment, and that the lithium ion perhaps depolarizes the resting membrane potential back to the normal level. They further support the prevailing hypothesis that manic-depressive illness may be caused by the hyperpolarization of the resting membrane potential, which, in turn, may be caused by the changes in ionic conductance (permeability) of the membranes. Sodium ions in sodium valproate do not significantly affect the resting membrane potential since they do not significantly change in the serum.