FIG. 3.

DA receptor agonists induce internal calcium release in hESC colonies. (A) Microphotograph (4× lens) showing iontophoretic micropipette (electrode) positioned next to a hESC colony. (B₁) Infrared photograph of the glass electrode and the edge of the hESC colony. (B₂) Fluorescent image of an hESC colony loaded with Oregon green 488 Bapta-1. Drawing marks the iontophoretic electrode filled with D1 agonist SKF38393. (B₃) SKF-induced calcium transients recorded simultaneously at 2 regions of interest (ROI 1 and ROI 2). Bottom trace depicts time course of the SKF iontophoretic pulse. (C₁) Photograph of the QP-filled electrode and the edge of the same hESC colony shown in (B₁–B₃). (C₂) Fluorescence image acquired with NeuroCCD. Drawing marks position of the QP electrode (D2 agonist). (C₃) QP-induced calcium transients recorded simultaneously at two ROIs (ROI 1 and ROI 2). (D) Calcium transients evoked by ATP, SKF, or QP superimposed on the same amplitude and time scale. Each trace is a spatial average of 9–16 pixels. Vertical dashed line marks the onset of the drug ejection. (E) Peak amplitude of the calcium transient averaged across all successful tests within a group: ATP (n=8), SKF (n=4), QP (n=9), and cocktail SKF+QP (n=6). ***ANOVA (P<0.0001); #P>0.05. (F) Same as in (E) except time period between stimulus onset and calcium peak was averaged. ***ANOVA (P<0.0001).