Figure 2. Effect of chlorpromazine on the increases in intracellular Calcium²+ concentration ([Calcium²+]ⁱ) and force induced by norepinephrine. A: Representative recordings showing changes in the fluorescence ratio and force development induced by 1 micro Meter norepinephrine in normal physiologic saline solution (PSS). The elevations in [Calcium²+]ⁱand developed force were expressed in percentage, assigning the values in normal (5.9 mM Potassium sup +)-PSS and steady state of 80 mM Potassium sup + -PSS to be 0 and 100%, respectively. (B and C) Effects of various concentrations of chlorpromazine on changes in [Calcium²+]ⁱ(B) and force development (C) induced by 1 micro Meter norepinephrine in normal PSS. The strips were pretreated with 0 M (open circle; control), 10 nM (closed circle), 100 nM (closed triangle), and 1 micro Meter (closed square) chlorpromazine. Chlorpromazine was applied for 10 min before and was present during the application of 1 micro Meter norepinephrine. The abscissa scales in (B) and (C) show the time (in minutes) after the application of 1 micro Meter norepinephrine. The mean values with SE bars are shown (n = 3-5). The number of experiments refers to the number of strips from each different animal.