The action of ouabain in promoting the release of catecholamines.

It is suggested that ouabain promotes catecholamine release by causing a rise in intracellular Na+ which, in turn, causes an elevated steady-state level of intracellular Ca2+. It is suggested that the Na+-K+-ATPase is not directly involved in exocytosis at either adrenergic or cholinergic synapses.