Figure 6. In vitro experiments with either timolol or glutathione confirmed the cardioprotective effects of timolol via prevention of increased basal free Ca²⁺ in diabetic cardiomyocytes due to a restoration in Ca²⁺ spark parameters.

Effects of either 10-μM TIM or 4-mM GSH incubation of diabetic cardiomyocytes for 1 hour on the fluorescence changes related with Ca²⁺ sparks amplitude (A), sparks frequency (B), time to peak amplitude TP (left) and full duration half maximum, FDHM (right) (C), and full width of half maximum of the Ca²⁺ sparks (D). Bars represent control (CON; n_rat = 5, n_cell = 30, n_spark = 102), diabetic (DM; n_rat = 5, n_cell = 35, n_spark = 122) and TIM or GSH incubated (+TIM or +GSH) diabetic (n_rat = 6, n_cell = 38 or n_cell = 32, n_spark = 120 or n_spark = 104) groups, respectively. Values are expressed as mean ± SEM. Significant at ^*p<0.05 vs. CON, ^†p<0.05 vs. DM.