Paricalcitol Attenuates Metabolic Syndrome-Associated Heart Failure through Enhanced Mitochondrial Fusion.

Objectives: Transition from cardiac hypertrophy to failure involves adverse metabolic reprogramming involving mitochondrial dysfunction. We have earlier shown that vitamin D deficiency induces heart failure, at least in part, through insulin resistance. However, whether activation of vitamin D receptor (VDR) can attenuate heart failure and underlying metabolic phenotype requires investigation. Thus, we aimed to assess the cardioprotective potential of paricalcitol, a vitamin D receptor-activator, against cardiac hypertrophy and failure in high-fat high-fructose-fed rats. Methods: Male Sprague Dawley rats were fed control (Con) or high-fat high-fructose (HFHFrD) diet for 20 weeks. After 12 weeks, rats from HFHFrD group were divided into the following: HFHFrD, HFHFrD+P (paricalcitol i.p. 0.08 µg/kg/day) and HFHFrD+E (enalapril maleate i.p. 10 mg/kg/day). Intraperitoneal glucose tolerance test, blood pressure measurement, and 2D echocardiography were performed. Cardiac fibrosis was assessed by Masson's trichrome staining of paraffin-embedded heart sections. Mitochondrial DNA and proteins, and citrate synthase activity were measured in rat hearts. VDR was silenced in H9c2 cardiomyoblasts, and immunoblotting was performed. Results: Paricalcitol improved glucose tolerance, serum lipid profile, and blood pressure in high-fat high-fructose-fed rats. Paricalcitol reduced cardiac wall thickness and increased ejection fraction in high-fat high-fructose-fed rats but had no effect on perivascular fibrosis. PGC1-α was upregulated in the HFHFrD+P group compared to the HFHFrD group, but there was no significant difference in mitochondrial content. Citrate synthase activity was significantly higher in the HFHFrD+P group compared to the HFHFrD group. Rat hearts of the HFHFrD+P group had significantly higher expression of mitofusins. H9c2 cells with VDR knockdown showed significantly lower expression of Mfn2. Improvement in the HFHFrD+P group was comparable with that in the HFHFrD+E group. Conclusions: Paricalcitol reverses cardiac dysfunction in rats with metabolic syndrome by enhancing mitochondrial fusion. We demonstrate repurposing potential of the drug currently used in end-stage kidney disease.

Musa balbisiana Fruit Rich in Polyphenols Attenuates Isoproterenol-Induced Cardiac Hypertrophy in Rats via Inhibition of Inflammation and Oxidative Stress.

Musa balbisiana Colla (Family: Musaceae), commonly known as banana and native to India and other parts of Asia, is very rich in nutritional value and has strong antioxidant potential. In the present study, we have developed Musa balbisiana (MB) fruit pulp powder and evaluated its cardioprotective effect in cardiac hypertrophy, which is often associated with inflammation and oxidative stress. An ultra-high-pressure liquid chromatography-mass spectrometer (UPLC-MS/MS) has been used for the detection and systematic characterization of the phenolic compounds present in Musa balbisiana fruit pulp. The cardioprotective effect of MB was evaluated in a rat model of isoproterenol- (ISO-) induced cardiac hypertrophy by subcutaneous administration of isoproterenol (5 mg/kg-1/day-1), delivered through an alzet minipump for 14 days. Oral administration of MB fruit pulp powder (200 mg/kg/day) significantly (p < 0.001) decreased heart weight/tail length ratio and cardiac hypertrophy markers like ANP, BNP, ß-MHC, and collagen-1 gene expression. MB also attenuated ISO-induced cardiac inflammation and oxidative stress. The in vivo data were further confirmed in vitro in H9c2 cells where the antihypertrophic and anti-inflammatory effect of the aqueous extract of MB was observed in the presence of ISO and lipopolysaccharide (LPS), respectively. This study strongly suggests that supplementation of dried Musa balbisiana fruit powder can be useful for the prevention of cardiac hypertrophy via the inhibition of inflammation and oxidative stress.

Inhibition of SGLT1 abrogates preconditioning-induced cardioprotection against ischemia-reperfusion injury.

BACKGROUND: Recently, we reported Na+/glucose co-transporter (SGLT1) expression in mouse and human heart. We speculated that SGLT1 might play an important role in ischemic preconditioning-induced cardioprotection. Therefore, the present study was designed to find the role of SGLT1 in ischemic preconditioning-induced cardioprotection. METHODS: Hearts isolated from SD male rats were subjected to either ischemia-reperfusion injury (I/R) (15 min global ischemia followed by 20 min reperfusion) or ischemic preconditioning (IPC) (3 cycles of 2 min global ischemia separated by 3 min reperfusion) followed by I/R in presence and absence of phlorizin, an SGLT1 inhibitor. RESULTS: IPC increased membrane SGLT1 expression in rat heart as observed by immunoblotting and immunohistochemistry. Hearts from I/R group showed significant increase in oxidative stress levels and marked myocardial injury as compared to control. We also observed significant increase in apoptotic parameters in I/R heart, as measured by caspase-3 activity, TUNEL positive nuclei and gene expression analysis. Significant improvement in oxidative stress, apoptosis parameters and cardiac injury was observed in I/R hearts when subjected to IPC. However, all beneficial effects of preconditioning were lost when hearts were pre-treated with phlorizin. CONCLUSION: Present study indicated that inhibition of SGLT1 by phlorizin abrogated the beneficial effect of ischemic-preconditioning and for the first time, provides evidence that SGLT1 plays a crucial role in ischemic preconditioning-induced cardioprotection.