Green tea modulation of inducible nitric oxide synthase in hypoxic/reoxygenated cardiomyocytes

Hypoxia/reoxygenation (H/R) is one of the causes of the increased expression of inducible nitric oxide synthase (iNOS) in cardiomyocytes. Since an aberrant NOS induction has detrimental consequences, we evaluated the effect of a green tea extract (GTE) on the NOS induction and activity in HIR-cardiomyocytes to define a nutritional strategy. Cultured rat cardiomyocytes were exposed to H/R in the presence of two concentrations of a green tea extract (GTE), which is reported to inhibit NOS expression and activity in different cells. In cultured cardiomyocytes two NOS isoforms were constitutively expressed, but only iNOS was induced by H/R. GTE supplementation at the lowest concentration, comparable to that in human plasma after dietary consumption, was ineffective, while the highest, comparable to that achievable by dietary supplements, counteracted the effect of H/R on iNOS induction and activity. It is necessary to verify in humans the relationship between the modulation of NO production and green tea dietary consumption. (c) 2005 Elsevier SAS. All rights reserved.