Fig. 4

Exercise increases Ca²⁺ store content in irradiated muscle. Ca²⁺ analysis from 3-month-old WT mouse irradiated (Rad RL) and non-irradiated (Rad CL) muscle after 1 month of VWR exercise (running) or sedentary control. a Resting cytosolic Ca²⁺ measurements from fura-2-loaded single FDB myofibers. Biological n = 9 mice per condition, technical n value displayed directly on the graph as the number of myofibers measured per condition. b Single myofiber cytosolic resting Ca²⁺ concentration frequency distribution for non-irradiated contralateral (Rad CL) and c irradiated (Rad RL) FDB myofibers. d TA whole muscle protein lysate immunoblot of non-irradiated (Rad CL) and irradiated (Rad RL) sedentary and exercised muscle. e Quantification of calsequestrin1 protein expression from d as normalized to GAPDH. N = 3 mice per condition. f Total SR store Ca²⁺ content measurements from isolated non-irradiated and irradiated single FDB myofibers loaded with fura-FF and perfused with ICE store-depleting solution from sedentary and exercised mice. Biological n = 4–5 mice per condition, technical n value displayed directly as individual data points on graph as the number of myofibers measured per condition. Two-way ANOVA with multiple comparisons *p < 0.05, **p < 0.01, ***^/###p < 0.001, ^####p < 0.0001. Isolated asterisks denote the ANOVA group effect of exercise. Isolated pound signs denote the ANOVA group effect of radiation. A significant interaction between variables was observed for the analysis of resting cytosolic Ca²⁺, p = 0.0375. Data displayed as mean ± s.e.m