Increased ouabain binding after repeated noradrenergic stimulation.

Acute noradrenergic stimulation has previously been shown to stimulate brain (Na+, K+)-adenosine triphosphatase activity. Effects of repeated stimulation with piperoxane were examined in the present study. Daily piperoxane increased ouabain binding, measured 24 h after the last dose, after 4 days or 3 weeks treatment; K+-p-nitrophenylphosphatase was increased after 3 weeks. Prazosin, which, like piperoxane, activates presynaptic noradrenergic neurons but, unlike piperoxane, blocks postsynaptic receptors, did not increase K+-p-nitrophenylphosphatase, and decreased ouabain binding after 3 weeks.