Figure 6. Different increases in [Ca²⁺]_i induced by different levels of heat stimulation with and without the TRPV channel inhibitor RuR.

The thermal changes were carried out at the time points indicated by arrows. Data are mean ± SEM of 3 – 11 experiments. The corresponding mean heat stimulation temperature is noted near the Ca²⁺ traces. (A) Rise of bath solution temperature from room temperature to nearly 50 °C resulted in more elevated Ca²⁺ levels compared to those after low heat stimulation (35 °C). Traces show intracellular Ca²⁺ levels measured from several neighboring cells with high heat stimulation (filled circles) (n = 11), low heat stimulation (filled quadrangles) (n = 4) and without heat (open circles) (n = 4). (B) Summary of the experiments with low and high heat stimulation in HCEC. The asterisks (*) indicate significant differences between controls (Ca²⁺ base levels; n = 4) and the effect of high heat stimulation on [Ca²⁺]_i (n = 11) and low heat-induced increased Ca²⁺ levels (n = 4). (C) The low heat-induced Ca²⁺ increase was significantly reduced in the presence of RuR at the beginning of the low heat response (10 µM) (n = 5). (D) The high heat-induced Ca²⁺ increase was significantly reduced in the presence of RuR after the high heat response (n = 3). (E) Summary of the experiments with RuR after low and high heat stimulation in HCEC. The asterisks (*) indicate significant differences between the effect of RuR at high heat stimulation on [Ca²⁺]_i (n = 3 – 11) and low heat stimulation on [Ca²⁺]_i (n = 4 – 5).