Fig. 6

Diode laser heat induced calcium transients: stimulus-response characteristics of TRPV1 transfected HEK cells. a Original trace of a single HEK cell transiently transfected with TRPV1, which showed significant responses to 190 mW stimuli of 1 and 2 ms duration. b Responder rates of TRPV1 transfected HEK cells as a function of stimulus duration for different laser powers (80, 135, 190 mW; T₅₀ responder thresholds given as dotted lines; n = 142–213). c At fixed stimulus duration of 5 ms the T₅₀ was at 104 mW (n = 666, 0.52 mJ). d Calcium influx linearly increased with increasing stimulus duration at fixed laser power, with Stevens’ exponents between 0.40 and 0.85 (slopes). e Calcium influx linearly increased with increasing laser power at fixed duration, with a Stevens’ exponent of 0.62. Dashed lines indicate upper limit of non-specific heat-induced fluorescence artefacts [18]