Effects of G-1 on ISO-induced changes in ICa,L in fresh cardiomyocytes. A, Bright-field images and corresponding immunofluorescence of cardiac troponin T of cardiomyocytes. B, Representative current-voltage traces in the presence of the specified treatment conditions. C, Current-voltage relationships of ICa,L in cardiomyocytes treated with vehicle (control) or the specified concentrations of ISO [One-way ANOVA, Tukey post hoc Tests. Con vs ISO 1μM: −20mV: p = 0.1296; −10mV: p = 0.0086; 0mV: p = 0.0052; +10mV: p = 0.0144; +20mV: p = 0.0725. Con vs ISO 10μM: −20mV: p = 0.0037; −10mV: p = 0.0001; 0mV: p = 0.0002; +10mV: p = 0.0005; +20mV: p = 0.0032. ISO 1 μM vs ISO 10μM: −20mV: p = 0.2670; −10mV: p = 0.2087; 0mV: p = 0.3438; +10mV: p = 0.3746; +20mV: p = 0.3795. D, Current-voltage relationship of ICa,L in cardiomyocytes treated with vehicle (control) ISO 10μM, or G-1. [One-way ANOVA, Tukey post hoc tests: Con vs ISO 10μM: −30mV: p = 0.1176; −20mV: p = 0.001; −10mV: p < 0.0001; 0mV: p < 0.0001; +10mV: p < 0.0001; +20mV: p = 0.0006; +30mV: p = 0.0425. Con vs G1+ISO 10μM: −30mV: p = 0.1319; −20mV: p = 0.8080; −10mV: p = 0.6723; 0mV: p = 0.8673; +10mV: p = 0.9903; +20mV: p = 0.9705; +30mV: p = 0.8539. ISO 10μM vs G1+ISO 10μM: −30mV: p = 0.0029; −20mV: p = 0.0084; −10mV: p = 0.0002; 0mV: p = 0.0001; +10mV: p = 0.0002; +20mVp = 0.0008; +30mV: p = 0.0232]. E, Steady-state inactivation curves in PMCMs treated with vehicle (control) or the specified concentrations of ISO, [One-way ANOVA, Tukey post hoc tests: Con vs ISO 1μM: −50mV: p = 0.0236, −40mV: p = 0.0173; −30mV: p = 0.0027; −20mV: p = 0.0001; −10mV: p = 0.0001; 0mV: p = 0.0434. Con vs ISO 10μM: −50mV: p = 0.0609; −40mV: p = 0.0528; −30mV: p = 0.0059; −20mV: p = 0.0002; −10mV: p = 0.0001: 0mV: p = 0.0001. ISO 1μM vs ISO 10μM: −50mV: p = 0.8747; −40mV: p = 0.8337; −30mV: p = 0.9206; −20mV: p = 0.9620; −10mV: p = 0.9980; 0mV: p = 0.9980]. F, Steady-state inactivation curves in PMCMs treated with vehicle, ISO 10μM, or ISO 10μM + G-1 [One-way ANOVA, Tukey post hoc tests: Con vs.ISO 10μM. −30mV: p = 0.0033: −20mV: p = 0.0005: −10mV: p = 0.001. Con vs G1+ISO 10μM: −30mV: p = 0.0003: −20mV: p = 0.0091; −10mV: p = 0.7481. ISO 10μM vs G1 + ISO 10μM: −30mV: p = 0.1715; −20mV: p = 0.6639; −10mV: p = 0.0118]. Data are presented as mean ± SD of n = 6–9 cells for each condition. *, p < 0.05 control vs 1 μM ISO; +, p < 0.05 control vs 10 μM ISO; ^, p < 0.05 10 μM ISO vs 10 μM ISO + G1; #, p < 0.05 control vs 10 μM ISO + G1. Scale bars, 50 μm.