Figure 3.

Dependence of the ACh response on extracellular calcium. (A) Response of a single astrocyte to a 2-s application of 100 μM ACh in the presence of normal calcium (2 mM Calcium), where external calcium was substituted with 0.5 mM EGTA; (0 mM Ca) and a second challenge with ACh in 2 mM calcium (Recovery). Removing extracellular calcium abolished the ACh-induced calcium response. Similar results were obtained from 17 cells. (B) Averaged responses to a 2-s application of 100 μM ACh in the presence of 100 μM CdCl₂. Robust ACh responses were observed in the presence of the VGCC blocker (+Cd). These responses were similar to those observed from untreated cells (Control). Data are the mean ± SEM from 40 cells (+Cd) and 42 cells (Control). ACh was applied in the presence of 500 nM atropine.