Fig. 4. Ca²⁺ release from stores contributes to the excitation of CBF. (A) Caffeine stimulated CBF. Both 1 mmol l^-1 (open circles, N=5, P0.001) and 10 mmol l^-1 (filled squares, N=6, P0.0003) caffeine increases CBF, however, the effects of 1 mmol l^-1 caffeine decline over time. (B) Caffeine (Caff) excitation is reduced by the ryanodine receptor blocker dantrolene (Dant). 10 mmol l^-1 Caffeine (N=6) induced CBF excitation is significantly reduced in 50 µmol l^-1 dantrolene (N=7, P0.00004). 100 µmol l^-1 dopamine and 10 µmol l^-1 TPep-NLS excitation is also reduced by 50 µmol l^-1 dantrolene (N=6, P0.0002; N=6, P0.00009, respectively). ^*Significant change from mean basal levels.