Fig. 5.

Light-dependent changes in mitochondrial Ca²⁺ uptake and oxygen consumption rate in cells expressing the optometabolic constructs. (A, Left) Kinetics of mitochondrial Ca²⁺ transients (expressed as ΔR/R₀) elicited by histamine (Hist; 100 μM) in single HeLa cells cotransfected with 4mtD3cpv and mitoChR2(SSFO), mitoChR2(Tr), or empty vector, preilluminated with a 10-s blue light pulse (2 mW/mm²) or pretreated with FCCP (1 μM). (A, Right) Mean values (±SEM; n ≥ 21 cells per condition) of the peak amplitude of mitochondrial Ca²⁺ increases. (B) Mean (±SEM; n = 9 independent experiments) OCR in control (empty vector) or mitoChR2(Tr)-YFP– or mitoChR2(SSFO)-YFP–transfected HeLa cells, before and after illumination with a 10-s blue light pulse (Materials and Methods). Change of OCR in cells expressing mitoChR2(SSFO)-YFP is underestimated because OCR is the mean of the whole-cell population and the transfection efficiency was ∼60%. ***P < 0.001. NS, not significant.