[Stimulation by cyclic adenosine-3'5'-monophosphate by Na+, K+-activated ATPase from rabbit kidney]

Cyclic 3',5-AMP in vitro increased the activity of Na+, K+-ATPase, isolated from cortex and medulla of rabbit kidney. Maximal stimulating effect was observed in kidney cortex at 10(-6) M concentration and in medulla at 10(-4) M concentration of 3',5'-AMP. Under these conditions the enzymatic activity was increased by 24.6 +/- 4.1% and 27.9 +/- 7.7%, respectively. These data suggest that Na+, K+-ATPase, activated by cyclic 3',5'-AMP, is directly involved in the mechanism of Na+ transport in cells of osmoregulating organs.