Objectives:
It has been reported that sodium glucose co-transporter (SGLT) inhibitors lowering blood glucose in diabetic patients via inhibiting glucose re-absorption. Although it has not been clearly identified the effects of these inhibitors on heart function, these inhibitors may act like Na+/H+-exchanger (NHE) inhibitors. In this study, we were aimed to clarify the underlying cellular mechanism of a SGLT2-inhibitor, Dapagliflozin (DAPA), on hyperglycemic embryonic rat ventricular cells (H9c2 cell line) via electrophysiological measurements.
Materials and Methods:
One group of H9c2 cells were incubated with high glucose (25 mM) medium for 24-hours and 48-hours at 37 °C to obtain hyperglycemic (HG) cardiomyocytes. Another group of H9c2 cells were incubated together with high glucose medium and DAPA (D185360, TORONTO Research Chemicals; 100 nM or 1 μM). Intracellular ion concentrations, ([X]in), reactive oxygen species, ([ROS]in) and mitochondrial membrane potential, (MMP) were monitored via specific fluorescent dyes (DCFDA, FluoZin-3AM, JC-1, SNARF, FURA-2AM and SBFI) with confocal microscope and microspectrofluorometer. All data are presented as mean (± SEM) and statistical analysis performed by student t-test. Significance level considered at p<0.05 for all comparisons.
Results:
Due to the toxic effects of 1 μM DAPA incubation, all experiments were conducted with 100 nM DAPA incubated cells. [Na+]in levels were not significantly changed in any group. Moreover, increased [H+]in level in HG incubation (48-hours) significantly augmented following DAPA treatment (24-hours and 48-hours). However [Zn+2]in levels in HG incubated (24-hours and 48-hours) cells were significantly increased, DAPA treatment had no further effect. In addition, increased [Ca+2]in in HG reduced with DAPA treatment to control values. Importantly, DAPA treatment significantly reduced elevated [ROS]in but did not improve depolarized MMP in HG cardiomyocytes.
Conclusion:
In conclusion these results indicate that DAPA treatment restores [H+]in and [ROS]in homeostasis and improve contraction-relaxation activity of the heart in HG conditions.
Keywords: Hyperglycemia, Sodium-Glucose Co-Transporter Inhibitors, Oxidative Stress, Heart Function, Intracellular Ionic-Homeostasis
