Figure 1.

Summary of experimental observations on temperature dependent [Ca²⁺]_i activity [24]. (a) Fluorescence recordings from three individual astrocytes in three different experiments. The temperature was changed between 20°C and 30°C by using heated and nonheated perfusion buffer (indicated by the bar). Fluorescent amplitude ΔF is defined as the fluorescent temporal signal normalised by the initial signal strength. (b) [Ca²⁺]_i traces from three different cultured astrocytes at 28°C and 20°C. Note that the transient fluorescence changes have a smaller spike width and occur less frequently at higher temperature. The recordings were separated by 5 min. (c) Average number of cells which exhibited a [Ca²⁺]_i spike (average from four independent experiments). The number of responsive cells at 20°C was set to 100% and compared to the number of responsive cells at different temperatures or to the recovery at 20°C (bars indicate s.e.; ^∗ P < 0.05). ((d), (e)). Average spike width of the fluorescent signals of all experiments obtained from cultured astrocytes (d) and in slices (e) determined at different temperatures as indicated (error bars indicate s.e.). (f) From the data the duration of the spike width is plotted as a function of temperature for astrocytes from culture (black dots) and brain slices (circles). The data points were fitted by f(T) = 620 s · exp⁡(−0.109T/°C) (^∗∗ P < 0.005).