[Sites responsible for stimulation of brain Na,K-ATPase by serotonin]

Serotonin (10(-6)-10(-3) M) stimulates Na,K-ATPase in the rat brain cortex homogenate with a maximal effect at 10(-4) M. Deseril (10(-5) M), antagonist of serotonin receptors, removes the stimulating effect. Deseril has no influence on noradrenaline-induced ATPase activation; the alpha-adrenergic blocker phentolamine does not affect serotonin activation. The effects of the two transmitters are additive. It is assumed that the mediators interact with different membrane sites, serotonin activation being initiated via the serotonin receptors.