Hyperglycemia increases endothelial superoxide that impairs smooth muscle cell Na+-K+-ATPase activity.

Publication/Presentation Date

3-1-2002

Abstract

Nitric oxide (NO) plays an important role in the control of numerous vascular functions including basal Na+-K+-ATPase activity in arterial tissue. Hyperglycemia inhibits Na+-K+-ATPase activity in rabbit aorta, in part, through diminished bioactivity of NO. The precise mechanism(s) for such observations, however, are not yet clear. The purpose of this study was to examine the role of superoxide in modulating NO-mediated control of Na+-K+-ATPase in response to hyperglycemia. Rabbit aorta incubated with hyperglycemic glucose concentrations (44 mM) demonstrated a 50% reduction in Na+-K+-ATPase activity that was abrogated by superoxide dismutase. Hyperglycemia also produced a 50% increase in steady-state vascular superoxide measured by lucigenin-enhanced chemiluminescence that was closely associated with reduced Na+-K+-ATPase activity. Specifically, the hyperglycemia-induced increase in vascular superoxide was endothelium dependent, inhibited by L-arginine, and stimulated by N(omega)-nitro-L-arginine. Aldose reductase inhibition with zopolrestat also inhibited the hyperglycemia-induced increase in vascular superoxide. In each manipulation of vascular superoxide, a reciprocal change in Na+-K+-ATPase activity was observed. Finally, a commercially available preparation of Na+-K+-ATPase was inhibited by pyrogallol, a superoxide generator. These data suggest that hyperglycemia induces an increase in endothelial superoxide that inhibits the stimulatory effect of NO on vascular Na+-K+-ATPase activity.

Volume

282

Issue

3

First Page

560

Last Page

566

ISSN

0363-6143

Disciplines

Diagnosis | Medicine and Health Sciences | Other Analytical, Diagnostic and Therapeutic Techniques and Equipment | Radiology

PubMedID

11832341

Department(s)

Department of Radiology and Diagnostic Medical Imaging

Document Type

Article

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