Nitric oxide and cyclic GMP are elevated in the hearts of copper-deficient rats

Copper deficiency depresses cardiac contractile function. Nitric oxide, via stimulation of cyclic GMP production, impairs cardiac contraction. We examined the hypothesis that cardiac nitric oxide and cyclic GMP production increase in copper deficiency, which would provide a possible explanation for reduced contractile force in copper-deficient animals. Rats were fed diets that were either copper-adequate (6.3 mu g Cu/g diet) or copper-deficient (0.4 mu g Cu/g diet) and given water with or without nitric oxide synthase inhibitor (L-NAME, 0.7 g/l) for 5 weeks. Copper deficiency was confirmed by depressed organ copper concentration, anaemia and enlarged hearts. Combined nitrate and nitrite concentrations (NOx) were elevated in the hearts and urine of copper-deficient rats. Cyclic GMP was elevated in hearts of copper-deficient rats. NOx concentrations in hearts and urine were depressed by chronic L-NAME treatment. These findings suggest that nitric oxide and cyclic GMP could contribute to the depressed cardiac contraction of copper deficiency. Med Sci Res 26:495-497 (C) 1998 Lippincott-Raven Publishers.