FIGURE 7.

Deletion of MCU alters cytosolic Ca²⁺ transients induced by activation of metabotropic purinergic receptors by ATP. (A) Representative traces of relative cytoplasmic [Ca²⁺] measured with Fura-2 and represented as R/R₀ for normalization, where R is the ratio of Fura-2 fluorescence at 340:380 nm excitation. ATP-induced responses in transformed fibroblasts classified as single spike (green trace), oscillations (blue trace), or sustained rise of [Ca²⁺]_cyt (light blue trace). (B) Percent (%) of ATP-induced responses classified as single spike (green), oscillatory (blue), and sustained rise of [Ca²⁺]_cyt (light blue) in transformed fibroblasts and MCU-KO fibroblasts. Each cell was individually analyzed (n = number of cells). (C) Height of initial peak R/R₀ after addition of ATP (n = number of cells; mean ± SEM, ****p < 0.0001, one-way ANOVA). (D) Representative traces of oscillatory responses induced by ATP in transformed (black trace), MCU-KO clone 5 (green trace), and MCU-KO clone 8 (blue trace) fibroblasts. (E) Number of oscillations over 300 s in responses classified as oscillatory (n = number of cells; mean ± SEM, ****p < 0.0001, one-way ANOVA).