In this study, we examined the effect of
vanadate treatment on cardiac changes recognized in diabetic rats. In addition, the possible contribution of
thyroid hormones to
vanadate's effect on
alloxan-diabetic atria was also investigated. Administration of
alloxan to rats, as expected, resulted in
hyperglycemia; hypoinsulinemia reduced
thyroid hormone levels, decreased
body weight and depressed cardiac function.
Vanadate treatment of diabetic rats normalized
blood glucose and serum
thyroid hormone levels, neither were serum
insulin levels of diabetic animals corrected after
vanadate treatment.
Vanadate treatment, however, did not affect the
body weights of diabetic rats. Spontaneously-beating atria from diabetic rats were found to have decreased rates but increased forces of contractions compared with those from controls. On the other hand, the responsiveness of diabetic atria to both inotropic and chronotropic effects of
isoprenaline was found to be decreased.
Vanadate treatment resulted in the normalization of these alterations observed in diabetic atria. These results thus indicate that the normalizing effect of
vanadate on diabetes-induced
hypothyroidism may contribute to its effect in preventing cardiac changes observed at the early stage of diabetes.