Abstract 13874: Elevated [Na ⁺ ] _i in Cardiac Myocytes from Diabetic Rats Due to Enhanced Na ⁺ - Glucose Cotransport

TL;DRAbstract

Intracellular Na + concentration ([Na + ] i ) is a key regulator of cardiac Ca 2+ cycling, contractility and metabolism. [Na + ] i is elevated in myocytes from failing hearts, leading to arrhythmias and oxidative stress. We hypothesized that myocyte [Na + ] i is also increased in type-2 diabetes (T2D) due to enhanced activity of the Na + -glucose cotransporter (SGLT). To test this hypothesis, we used myocardial tissue from humans with T2D and an animal model of late-onset T2D (HIP rats). We found increased SGLT expression in failing hearts from patients with T2D compared to non-diabetic individuals (by 55±16%) and in HIP rat hearts ( vs . age-matched wild-type, WT, littermates; by 59±17%). [Na + ] i , measured with the fluorescent indicator SBFI, is increased in myocytes from diabetic HIP rats, both at rest (14.7±0.9 mM compared to 11.4±0.7 mM in WT) and during electrical stimulation at 2 Hz (17.3±0.8 mM vs . 15.0±0.7 mM in WT). However, the Na + /K + -pump function (measured as the ra

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