A ouabain-sensitive hyperpolarization in rat striatal neurones in vitro.

Intracellular recordings were made from rat striatal neurones in vitro. In the presence of intracellular caesium and extracellular tetraethylammonium chloride (TEA) (5 mM) and barium (3 mM), long-lasting plateau potentials developed followed by a prominent voltage independent hyperpolarization which lasted several seconds. A similar afterhyperpolarization was observed when calcium was replaced by barium. The afterhyperpolarization was reduced in a potassium free medium and reversibly abolished in a Na+-free solution or by cooling the slice to 21-24 degrees C. It was also irreversibly blocked by ouabain (50 microM). This hyperpolarization may therefore result from the activation of a Na+,K+-ATPase electrogenic pump.