RESUMO
Oxidative stress has been implicated in the pathogenesis of cardiac hypertrophy and associated heart failure. Cardiac tissue grows in response to pressure or volume overload, leading to wall thickening or chamber enlargement. If sustained, this condition will lead to a dysfunctional cardiac tissue and oxidative stress. Calorie restriction (CR) is a powerful intervention to improve health and delay aging. Here, we investigated whether calorie restriction in mice prevented isoproterenol-induced cardiac hypertrophy in vivo by avoiding reactive oxygen species (ROS) production and maintaining antioxidant enzymatic activity. Additionally, we investigated the involvement of mitochondrial ATP-sensitive K+ channels (mitoKATP) in cardiac hypertrophy. CR was induced by 40% reduction in daily calorie ingestion. After 3 weeks on CR or ad libitum (Control) feeding, Swiss mice were treated intraperitoneally with isoproterenol (30 mg/kg per day) for 8 days to induce hypertrophy. Isoproterenol-treated mice had elevated heart weight/tibia length ratios and cardiac protein levels. These gross hypertrophic markers were significantly reduced in CR mice. Cardiac tissue from isoproterenol-treated CR mice also produced less H2O2 and had lower protein sulfydryl oxidation. Additionally, calorie restriction blocked hypertrophic-induced antioxidant enzyme (catalase, superoxide dismutase and glutathione peroxidase) activity repression during cardiac hypertrophy. MitoKATP opening was repressed in isolated mitochondria from hypertrophic hearts, in a manner sensitive to calorie restriction. Finally, mitoKATP inhibition significantly blocked the protective effects of calorie restriction. Altogether, our results suggest that CR improves intracellular redox balance during cardiac hypertrophy and prevents this process in a mechanism involving mitoKATP activation.
Assuntos
Restrição Calórica , Cardiomegalia/dietoterapia , Canais de Potássio/metabolismo , Animais , Antioxidantes/metabolismo , Cardiomegalia/induzido quimicamente , Cardiomegalia/metabolismo , Enzimas/metabolismo , Glibureto/farmacologia , Peróxido de Hidrogênio/metabolismo , Isoproterenol/efeitos adversos , Masculino , Camundongos , Estresse Oxidativo , Bloqueadores dos Canais de Potássio/farmacologia , Espécies Reativas de Oxigênio/metabolismoRESUMO
OBJECTIVES: We aimed to evaluate whether long-term treatment with the soluble non-bacterial fraction of kefir affects mean arterial pressure (MAP) and cardiac hypertrophy through the modulation of baroreflex sensitivity, ACE activity, and the inflammatory-to-anti-inflammatory cytokine ratio in spontaneously hypertensive rats (SHRs). METHODS: SHRs were treated with the soluble non-bacterial kefir fraction (SHR-kefir) or with kefir vehicle (SHR-soluble fraction of milk). Normotensive control Wistar Kyoto animals received the soluble fraction of milk. All treatments were administered by gavage (0.3 mL/100g/body weight), once daily for eight weeks. At the end, after basal MAP and Heart Rate (HT) measurement, barorreflex sensitivity was evaluated through in bolus administrations of sodium nitroprusside and phenylephrine (AP50 [arterial pressure 50%], the lower plateau, and HR range were measured). ACE activity and cytokines (TNF-α and IL-10) were evaluated by ELISA. Cardiac hypertrophy was analysed morphometrically. RESULTS: Compared to SHR control, SHR-kefir exhibited a significant decrease in both MAP (SHR: 184 ± 5; SHR-Kefir: 142 ± 8 mmHg), and HR (SHR: 360 ± 10; SHR-kefir: 310 ± 14 bpm). The non-bacterial fraction of kefir also reduced cardiac hypertrophy, TNF-α-to-IL10 ratio, and ACE activity in SHRs. SHR-kefir baroreflex sensitivity, resulted in a partial but significant recovery of baroreflex gain, as demonstrated by improvements in AP50, the lower plateau, and HR range. CONCLUSION: In summary, our results indicate that long-term administration of the non-bacterial fraction of kefir promotes a significant decrease in both MAP and HR, by improving baroreflex, and reduces cardiac hypertrophy in SHRs, likely via ACE inhibition, and reduction of the TNF-α-to-IL10 ratio.
Assuntos
Inibidores da Enzima Conversora de Angiotensina/sangue , Barorreflexo/efeitos dos fármacos , Pressão Sanguínea/efeitos dos fármacos , Cardiomegalia/dietoterapia , Hipertensão/dietoterapia , Kefir , Animais , Cardiomegalia/sangue , Modelos Animais de Doenças , Frequência Cardíaca , Hipertensão/sangue , Masculino , Ratos , Ratos Endogâmicos SHR , Ratos Endogâmicos WKYRESUMO
Pathological cardiac hypertrophy leads to derangements in lipid metabolism that may contribute to the development of cardiac dysfunction. Since previous studies, using high saturated fat diets, have yielded inconclusive results, we investigated whether provision of a high-unsaturated fatty acid (HUFA) diet was sufficient to restore impaired lipid metabolism and normalize diastolic dysfunction in the pathologically hypertrophied heart. Male, Wistar rats were subjected to supra-valvar aortic stenosis (SVAS) or sham surgery. After 6 weeks, diastolic dysfunction and pathological hypertrophy was confirmed and both sham and SVAS rats were treated with either normolipidic or HUFA diet. At 18 weeks post-surgery, the HUFA diet failed to normalize decreased E/A ratios or attenuate measures of cardiac hypertrophy in SVAS animals. Enzymatic activity assays and gene expression analysis showed that both normolipidic and HUFA-fed hypertrophied hearts had similar increases in glycolytic enzyme activity and down-regulation of fatty acid oxidation genes. Mass spectrometry analysis revealed depletion of unsaturated fatty acids, primarily linoleate and oleate, within the endogenous lipid pools of normolipidic SVAS hearts. The HUFA diet did not restore linoleate or oleate in the cardiac lipid pools, but did maintain body weight and adipose mass in SVAS animals. Overall, these results suggest that, in addition to decreased fatty acid oxidation, aberrant unsaturated fatty acid metabolism may be a maladaptive signature of the pathologically hypertrophied heart. The HUFA diet is insufficient to reverse metabolic remodeling, diastolic dysfunction, or pathologically hypertrophy, possibly do to preferentially partitioning of unsaturated fatty acids to adipose tissue.