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Elevated myocardial fructose and sorbitol levels are associated with diastolic dysfunction in diabetic patients, and cardiomyocyte lipid inclusions in vitro.

ABSTRACT: Diabetes is associated with cardiac metabolic disturbances and increased heart failure risk. Plasma fructose levels are elevated in diabetic patients. A direct role for fructose involvement in diabetic heart pathology has not been investigated. The goals of this study were to clinically evaluate links between myocardial fructose and sorbitol (a polyol pathway fructose precursor) levels with evidence of cardiac dysfunction, and to experimentally assess the cardiomyocyte mechanisms involved in mediating the metabolic effects of elevated fructose. Fructose and sorbitol levels were increased in right atrial appendage tissues of type 2 diabetic patients (2.8- and 1.5-fold increase respectively). Elevated cardiac fructose levels were confirmed in type 2 diabetic rats. Diastolic dysfunction (increased E/e', echocardiography) was significantly correlated with cardiac sorbitol levels. Elevated myocardial mRNA expression of the fructose-specific transporter, Glut5 (43% increase), and the key fructose-metabolizing enzyme, Fructokinase-A (50% increase) was observed in type 2 diabetic rats (Zucker diabetic fatty rat). In neonatal rat ventricular myocytes, fructose increased glycolytic capacity and cytosolic lipid inclusions (28% increase in lipid droplets/cell). This study provides the first evidence that elevated myocardial fructose and sorbitol are associated with diastolic dysfunction in diabetic patients. Experimental evidence suggests that fructose promotes the formation of cardiomyocyte cytosolic lipid inclusions, and may contribute to lipotoxicity in the diabetic heart.

SUBMITTER: Daniels LJ

PROVIDER: S-EPMC7870957 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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Elevated myocardial fructose and sorbitol levels are associated with diastolic dysfunction in diabetic patients, and cardiomyocyte lipid inclusions in vitro.

Daniels Lorna J LJ Annandale Marco M Koutsifeli Parisa P Li Xun X Bussey Carol T CT van Hout Isabelle I Bunton Richard W RW Davis Philip J PJ Coffey Sean S Katare Rajesh R Lamberts Regis R RR Delbridge Lea M D LMD Mellor Kimberley M KM

Nutrition & diabetes 20210208 1

Diabetes is associated with cardiac metabolic disturbances and increased heart failure risk. Plasma fructose levels are elevated in diabetic patients. A direct role for fructose involvement in diabetic heart pathology has not been investigated. The goals of this study were to clinically evaluate links between myocardial fructose and sorbitol (a polyol pathway fructose precursor) levels with evidence of cardiac dysfunction, and to experimentally assess the cardiomyocyte mechanisms involved in med ...[more]

PMID: 33558456

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Project description:Right ventricular (RV) diastolic function is impaired in patients with pulmonary arterial hypertension (PAH). Our previous study showed that elevated cardiomyocyte stiffness and myofilament Ca(2+) sensitivity underlie diastolic dysfunction in PAH. This study investigates protein modifications contributing to cellular diastolic dysfunction in PAH.RV samples from PAH patients undergoing heart-lung transplantation were compared to non-failing donors (Don). Titin stiffness contribution to RV diastolic dysfunction was determined by Western-blot analyses using antibodies to protein-kinase-A (PKA), C? (PKC?) and Ca(2+)/calmoduling-dependent-kinase (CamKII?) titin and phospholamban (PLN) phosphorylation sites: N2B (Ser469), PEVK (Ser170 and Ser26), and PLN (Thr17), respectively. PKA and PKC? sites were significantly less phosphorylated in PAH compared with donors (P<0.0001). To test the functional relevance of PKA-, PKC?-, and CamKII?-mediated titin phosphorylation, we measured the stiffness of single RV cardiomyocytes before and after kinase incubation. PKA significantly decreased PAH RV cardiomyocyte diastolic stiffness, PKC? further increased stiffness while CamKII? had no major effect. CamKII? activation was determined indirectly by measuring PLN Thr17phosphorylation level. No significant changes were found between the groups. Myofilament Ca(2+) sensitivity is mediated by sarcomeric troponin I (cTnI) phosphorylation. We observed increased unphosphorylated cTnI in PAH compared with donors (P<0.05) and reduced PKA-mediated cTnI phosphorylation (Ser22/23) (P<0.001). Finally, alterations in Ca(2+)-handling proteins contribute to RV diastolic dysfunction due to insufficient diastolic Ca(2+) clearance. PAH SERCA2a levels and PLN phosphorylation were significantly reduced compared with donors (P<0.05).Increased titin stiffness, reduced cTnI phosphorylation, and altered levels of phosphorylation of Ca(2+) handling proteins contribute to RV diastolic dysfunction in PAH.

Dataset Information

Elevated myocardial fructose and sorbitol levels are associated with diastolic dysfunction in diabetic patients, and cardiomyocyte lipid inclusions in vitro.

Publications

Elevated myocardial fructose and sorbitol levels are associated with diastolic dysfunction in diabetic patients, and cardiomyocyte lipid inclusions in vitro.

Similar Datasets

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