Fig. 4: L-carnitine suppressed heat-induced increases of intracellular Ca²⁺ concentration.

A Heat (>43 °C) induced an increase in Ca²⁺ influx (n = 205) whereas non-treated control cells maintained a constant Ca²⁺ baseline (n = 9). B Same experiment as shown in A, but in the presence of L-carnitine. L-carnitine (1 mmol/l) partially suppressed the heat-induced Ca²⁺ increase (n = 33). C Summary of the experiments with heat and L-carnitine. The asterisks (*) designate significant increases in [Ca²⁺]_i with heat (t = 300 s; n = 205; p < 0.005; paired tested) compared to control (t = 100 s). The hashtags (#) indicate statistically significant differences in fluorescence ratios between heat with and without L-carnitine (t = 300 s; n = 33–205; p < 0.005; non-paired tested).