Short term regulation of endothelial Na⁺-K⁺-pump activity by cGMP: A ¹³³Cs 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.

Key Words:

• ¹³³Cs NMR
• in vitro
• nitric oxide
• ion transport
• SIN-1
• L-NAME