Prevention of oxidative modifications in the heart of NO-deficient rats by (-)-epicatechin in the diet.

VALERIA CALABRÓ; BÁRBARA PIOTRKOWSKI; MANUEL BARRIOS; MÓNICA GALLEANO; CÉSAR G. FRAGA

San Pablo

Congreso; Free Radicals. VII Meeting of the SFRBM South American Group.; 2011

VII Meeting of the SFRBM South American Group

Modifications in dietary habits may be a possible strategy to prevent hypertension and its secondary effects. The aim of this study was to evaluate factors that may contribute to oxidative stress in myocardium during the initial stages of hypertension induced by L-NAME treatment, and its modulation by (-)-epicatechin (Epi). Sprague-Dawley rats were divided into 3 groups: Control (C), L-NAME (L: 360 mg/L), L-NAME + epicatechin (L+Epi: 360 mg/L + 0.4 mg/g diet). L and Epi were co-administered for 4 d in the drinking water and with solid diet, respectively. Animals were sacrificed and hearts were excised. Blood pressure in L group was significantly higher than in C, and Epi treatment prevented the increase. Heart to body weight ratio was similar in the 3 groups. Superoxide production by NADPH oxidase (determined by lucigenin assay) was significantly increased in L with respect to C, and Epi restored the activity to C values (C:1.0±0.1; L:1.4±0.1; L+Epi:0.9±0.1 cpm/mg protein) (p< 0.05 L vs C and L+Epi). This increase was not associated to a higher expression of p47phox subunit, which was similar in the 3 groups. Total SOD activity was not modified by the treatments, but Mn-SOD activity in L and L+Epi was significantly lower than in C (C:2.9±0.4; L:1.9±0.2; L+Epi:2.1±0.3 U MnSOD/mg protein) (p<0.05 vs C). In accordance, Mn-SOD expression was also lower in L with respect to the other groups studied (21% decrease respect to C and L+Epi). There was no significant change in catalase activity but glutathione peroxidase activity was higher in L group compared to C and L+Epi. These results point out that in the initial stages of hypertension oxidant production is increased in cardiac tissue, possibly related to both, a higher NADPH oxidase activity and a lower Mn-SOD activity. Dietary Epi prevented the effects associated with L treatment in the heart, and this effect could be interpreted as a protection from the increased oxidant production related to hypertension.  UBACyT 01/1111