FIGURE 6.

Photoactivatable RCaMP1h_T. (A) Stable photoactivation of RCaMP1h_T in HEK293 cells. RCaMP1h_T in HEK293T cells during prolonged photoactivation with 100% of 405 nm at ∼1.7 mW (magenta bar). Insets—HEK cells imaged by 561 nm before (top) and after (bottom) photoactivation (magenta dashed square). (B) RCaMP1h_T is a poor Ca²⁺-probe. Representative traces showing Ca²⁺-activity following the application of histamine (15 μM). (C) RCaMP1h_T maintains its artifacts. Following photoactivation, brief illumination by 405 nm yields large Ca²⁺-independent increases in fluorescence.