Short term regulation of endothelial Na+-K+-pump activity by cGMP: A133Cs magnetic resonance study

Abstract
The effect of nitric oxide radicals (NO) on the activity of porcine aortic endothelial Na+-K+-ATPase is reported. Measurements were made using an in vitro cell system and 133Cs magnetic resonance (NMR). It is shown that NO, through stimulation of guanylate cyclase, results in a reduction of pump activity. Similar observations were made using 8-Br-cGMP. Measurement of the cytosolic volume indicated no changes in volume during incubation with 8-Br-cGMP. Our measurements indicate a continuous regulation of endothelial Na+-K+-ATPase activity by endogenous NO. This regulation could be removed by L-Name, resulting in a small increase in pump activity.