Vanadate improves cardiac function and myocardial energy metabolism in diabetic rat hearts

Vanadium mimicking the metabolic effects of insulin is known to decrease serum glucose levels and to influence glucose metabolism in diabetes mellitus. However, it is unclear whether vanadium ameliorates the metabolic disorder in diabetic hearts causing myocardial dysfunction. The purpose of this study was to assess the effects of vanadium on cardiac performance and energy metabolism in diabetic rat hearts. Four groups of Wistar rats were studied: untreated control rats (group C, n = 8). vanadate-treated rats (group V, n = 10), untreated diabetic rats (group DM, n = 9) induced by streptozotocin. and vanadate-treated diabetic rats (group DMV, n = 8). Vanadate-treated rats drank a 1.5 mM sodium orthovanadate (Na3VO4) solution during a 4 week diabetic condition. Hearts were perfused with Krebs-Henseleit buffer after the diabetic duration. After the maximum left ventricular dP/dt and cardiac efficiency were calculated, the myocardial contents of ATP and creatine phosphate (P-Cr) and myocardial energy metabolism were assessed by cytosolic phosphorylation potential. Peak positive and negative dP/dt, and cardiac efficiency decreased significantly in group DM compared with group C, while there were no significant differences between groups C and DMV. The myocardial contents of ATP (micromol/g wet heart) and P-Cr (micromol/g wet heart), and cytosolic phosphorylation potential (M(-1)) increased from 2.72 +/- 0.46. 1.45 +/- 0.58. and 3,530 +/- 1,220 in group DM to 3.88 +/- 0.76, 3.81 +/- 1.36, and 11,200 +/- 2,400 in group DMV, respectively. It is concluded that vanadium restored the production of high energy phosphates in the myocardium and improved myocardial dysfunction by regulating metabolic processes in diabetic rat hearts.