Endobain E, a brain Na+, K+ -ATPase inhibitor, decreases norepinephrine uptake in rat hypothalamus.

The ability of an endogenous brain Na+, K+ -ATPase inhibitor, termed endobain E, to increase [3H]norepinephrine release in rat hypothalamus was previously reported. Endobain E effect on neurotransmitter uptake was studied by assaying [3H]norepinephrine uptake in rat hypothalamus preparations, to observe uptake inhibition, which reached 60% with endobain E equivalent to 100 mg fresh cerebral cortex, an effect achieved with 40 or 400 microM ouabain. Results support the proposal that endobain E behaves as an ouabain-like substance. Taken jointly results obtained on neurotransmitter release and uptake, the suggestion that endobain E may enhance norepinephrine availability in the synaptic gap and thus lead to an increase in noradrenergic activity is advanced.