Figure 4. Representative recordings showing changes in the fluorescence ratio and force development induced by 1 micro Meter U46619 in Calcium²+ -free physiologic saline solution in the absence (A) and presence (B) of 1 micro Meter chlorpromazine. Chlorpromazine was applied 10 min before and was present during the application of 1 micro Meter U46619. Note that chlorpromazine had no effect on the increase in intracellular Calcium²+ concentration and force induced by 1 micro Meter U46619.