Figure 2. Reactive oxygen species increase L-type Ca²⁺ channel sparklet activity in isolated cerebral arterial smooth muscle cells.

A, Representative TIRF images showing Ca²⁺ influx in an arterial myocyte before and after application of XO and HX (2mU/mL and 250 μmol/L, respectively). Traces show the time course of Ca²⁺ influx at the three circled sites before and after XO/HX. B, Ca²⁺ sparklet amplitude histograms before (white) and after XO/HX exposure (red). The solid black lines are best-fits to the control (q=34 nmol/L) and to the XO/HX (q=36 nmol/L) histograms with a multi-component Gaussian function where q is the quantal unit of Ca²⁺ influx (see Detailed Methods in the Online Supplement). C, Plot of Ca²⁺ sparklet site activities (nP_s) before and after XO/HX (n=8 cells). The red solid lines are the arithmetic means of each group and the dashed line marks the threshold for high-activity Ca²⁺ sparklet sites (nP_s≥0.2). D, Plot of the mean ± SEM Ca²⁺ sparklet density (Ca²⁺ sparklet sites/μm²) before and after XO/HX (n=8 cells). *P<0.05