Fig. 3. Ca²⁺ influx is necessary for increases in CBF. (A) Zero Cl^- bath (filled circles) excites CBF (N=5, P0.001), and the effect does not diminish over time. The excitatory effect is abolished (N=5, P0.10 compared to control) when 50 µmol l^-1 nifedipine (Nif; open squares) is included in the bath solution. (B) Excitation induced by 100 µmol l^-1 dopamine (DA) and 10 µmol l^-1 TPep-NLS (TPep) is also dependent on Ca²⁺ influx. Zero external Ca²⁺ (N=5, P0.008) and 50 µmol l^-1 nifedipine (N=5, P0.003) both significantly reduce dopamine excitation. Similarly, zero external Ca²⁺ (N=5, P0.00009) and 50 µmol l^-1 nifedipine (N=6, P0.01) also significantly reduce TPep-NLS excitation. ^*Significant change from mean basal levels (A) or significant reduction from stimulated levels (B).