Supplementary Figure 7: Effects of S100β depend on its ability to reduce extracellular calcium.

(a) Local application of the Ca²⁺-free buffer used to dilute S100β induces a small decrease of [Ca²⁺]_e (n = 6 recording sites in 6 slices from 3 rats), but does not cause bursting in NVsnpr neurons, in neither the interface ((b) extracellular recording; right trace, n = 11 cells in 11 slices from 6 rats) or the submerged configuration ((c) intracellular recording; right trace, n = 3 cells in 3 slices from 2 rats). (d) Local application of S100β diluted in the Ca²⁺-free buffer elicits neuronal bursting (left trace) in a cell from a preparation submerged in normal aCSF (with 1.6 mM Ca²⁺), but not after raising the [Ca²⁺]_e in the aCSF to 2.6 mM (n = 4 cells in 4 slices from 3 rats). (e) Local application of S100β diluted in a buffer containing 1.6 mM Ca²⁺ can still elicit bursting, when its concentration is increased to1 mM (right trace (n = 10 cells in 4 slices from 4 rats) to prevent its saturation, but not at the concentration of 129 µM; left trace (n = 5 cells in 3 slices from 3 rats).