Fig. 6.

Female ventricular myocytes have reduced Ca²⁺ levels in mitochondria matrix vs. males. A Representative confocal images of a ventricular myocyte (VCM) infected with matrix-targeted mtRCamp1h (Kd ~ 1.3 mmol/L) and mito-GFP, with a merged figure demonstrating correct probe localization. B Representative time course of mtRCamp1h fluorescence recorded in male (M) and female (F) VCMs. Myocytes were treated with isoproterenol (ISO, 50 nmol/L) for 3 min before pacing at 1 Hz for 5 min. C Mean ± SEM baseline matrix [Ca²⁺], and peak matrix [Ca²⁺], time to peak matrix [Ca²⁺], and decay rate during pacing, n = 13 M and n = 15 F VMs. N = 8 M and 8 F animals. *p < 0.05, p values were calculated using two-level random intercept model. D, E Representative western blots and pooled data for COX7RP normalized optical density in rat and human left ventricular (LV) tissue samples. Mean ± SEM, N = 8 M and N = 8 F rat; and N = 4 M and N = 4 F human samples. *p < 0.05, Student’s t-test