Figure 4 (a) Effect of ARB on MMP was evaluated with H9c2 cells using Rh-123. (i) Control. (ii) ISO (25 μM) yellow arrow indicated reduction in Rh-123 florescence. (iii) ARB (40 μM). (iv) ARB 40 μM + ISO (25 μM) white arrows indicate restoration of MMP for 24 hours and fluorescence intensity decreased as indicated by collapsed mitochondria matrix. (b) Cells-depicted fluorescence intensity was detected by spectrofluorometer. All experiments were performed in triplicate and all values were expressed as mean ± standard deviation of the mean. ARB, arbutin; ISO, isoproterenol hydrochloride; MMP, mitochondrial membrane potential; Rh-123, rhodamine 123.