Na+/Ca2+EXCHANGER INHIBITOR AMELIORATES IMPAIRED ENDOTHELIUM-DEPENDENT Na+RELAXATION INDUCED BY HIGH GLUCOSE IN RAT AORTA

Role of the Na(+)/Ca(2+) exchanger on the development of diabetes mellitus and its chronic complications

Diabetes mellitus (DM) is a serious metabolic disorder with micro- and macrovascular complications that results in significant morbidity and mortality. It is well established that cytosolic Ca(2+) play an important role in controlling insulin secretion in pancreatic β-cells. The Na(+)/Ca(2+) exchanger (NCX), an ion transport protein, is expressed in the plasma membrane of virtually all animal cells. NCX is a reversible carrier that can mediate the transport of Ca(2+) across the plasma membrane in both directions. Therefore, great efforts have been made to identify NCX associated with DM. NCX is expressed in several tissues, and acts in the protection against intracellular calcium overload; in the regulation of insulin secretion by beta cells, and in improving vascular endothelium-dependent relaxation. All these mechanisms are associated with DM pathogenesis and its chronic complications. Therefore, NCX is a candidate protein for the development of these disorders. Only a few studies investigated NCX in relation to chronic complications of diabetes, with inconclusive results.

KB-R7943 inhibits high glucose-induced endothelial ICAM-1 expression and monocyte-endothelial adhesion

Hyperglycemia is the major cause of diabetic angiopathy. The aim of our study was to evaluate the impact of KB-R7943, an inhibitor of Na+/Ca2+ exchanger (NCX) on cell growth and function of human "diabetic" endothelial cells (EC). Intercellular adhesion molecule-1 (ICAM-1) expression and NCX activity were determined after EC were exposed to high glucose in the absence and presence of KB-R7943. Coincubation of EC with high glucose for 24 h resulted in a significant increase of monocyte-endothelial cell adhesion and the expression of ICAM-1. These effects were abolished by KB-R7943 and KB-R7943 significantly decreased the activation of NCX induced by high glucose. These findings suggested that KB-R7943 may play a role in inhibiting expression of adhesion molecules by inhibiting the reverse activation of NCX.