Synaptosomal factors, regulating the activity of Na,K-ATPase and its sensitivity to neurotransmitters

The factors regulating the activity of synaptosomal Na,K-ATPase have been found in nerve endings cytosol. One of these (Mr 10,000) essentially inhibits, whereas the other one (Mr 60,000) in the presence of norepinephrine, 5-hydroxytryptamine and dopamine activates the Na,K-ATPase of synaptosomes. Regardless of their direct action on Na,K-ATPase, the effect of the activating factor increases in the presence of neurotransmitters. In cell ksap obtained by microsome precipitation the activating factor is absent.