Noradrenaline release induced by ouabain and vanadate in cat cerebral and peripheral arteries.

The effects of 10(-4) M ouabain and 10(-3) M vanadate (Na3VO4) on [3H]noradrenaline release from cat cerebral and femoral arteries was studied. Ouabain induced tritium secretion in cerebral arteries, but not in femoral ones, which was reduced by Ca suppression and potentiated by extracellular Na reduction to 11.9 mM. However, vanadate evoked tritium release from both kinds of vessels was unaffected under these experimental conditions. These data suggest: ouabain elicited secretion from adrenergic nerve endings is likely due to inhibition of the Na, K-ATPase and subsequent Ca influx through Na-Ca exchange, and vanadate action is mediated by another mechanism different to the Na pump blockade.