Role of endothelium-derived nitric oxide in stimulation of Na(+)-K(+)-ATPase activity by endothelin in rabbit aorta

Abstract

An endothelium-derived factor with the properties of nitric oxide (NO) has recently been implicated in the regulation of basal Na(+)-K(+)-adenosinetriphosphatase (ATPase) activity in vascular smooth muscle. To determine whether this factor also plays a role in the stimulation of ouabain-sensitive (OS) 86Rb uptake by specific agonists, studies were carried out using rabbit aortic rings. In endothelium-intact rings incubated for 3 h with Krebs-Henseleit solution containing 5.5 mM glucose, endothelin (ET) caused a concentration-dependent increase in OS 86Rb uptake (maximal increase = 205%, with 100 nM ET). Incubation with phenylephrine (Phe; 0.1 and 1 microM) or phorbol 12,13-dibutyrate (PDBu; 0.1 microM), under the same conditions, increased OS 86Rb uptake by 128, 144, and 140%, respectively. Removal of endothelium before incubation decreased the ability of ET to stimulate OS 86Rb uptake by 38-45%, but it did not diminish the stimulation of OS 86Rb uptake by Phe or PDBu. An increase in the concentration of glucose from 5.5 to 44 mM diminished ET-stimulated OS 86Rb uptake by 50% in endothelium-intact rings but had no effect on Phe- or PDBu-induced increases in OS 86Rb uptake. Addition of the NO synthase inhibitor NG-monomethyl-L-arginine (L-NMMA; 0.3 mM) to the medium decreased ET-stimulated OS 86Rb uptake by 40%. Guanosine 3',5'-cyclic monophophate (cGMP) formation in endothelium-intact rings was also increased (65%) by ET but not by Phe or PDBu. The increase in cGMP by ET was totally inhibited by L-NMMA or endothelium denudation.(ABSTRACT TRUNCATED AT 250 WORDS)