Figure 5.
ACh response in the presence of other divalent cations. (A) Fluorescence response of an astrocyte to a 2-s application of 100 μM ACh in external medium containing no added calcium and 10 mM SrCl2 (Sr). Response of the same cell to ACh application in the presence of 2 mM calcium (Ca). A robust response to ACh was observed in the presence of strontium comparable to that seen with calcium. (B) No transient was observed when ACh in 10 mM SrCl2 was applied in the presence of 1 μM TG [compare the control response (Sr) with the response from a treated cell (Sr + TG)]. (C) Rapid imaging in the presence of various divalent cations. Agonist (100 μM ACh) was applied 1 s into the acquisition, for 25 s. Three hundred images were acquired on an average at 17 Hz. At the end of each experiment, a second acquisition was done at the same rate to determine the rate of photobleaching. All data were corrected for photobleaching. Data are the averaged response from 21 cells (Sr), 16 cells (Ca), and 25 cells (Ba). (y-axis bar = 50% ΔF/F0.)