Figure 7
A line graph showing Z as a function of Cai. The x-axis represents Cai values ranging from 0.0 to 1.0. The y-axis represents Z values ranging from -2 to 2. The graph features two lines: a red line and a blue line. The red line starts at the bottom left, rises to a peak around Cai 0.5, and then declines. The blue line follows a similar pattern but peaks lower and declines more steeply. The label 'X+' is placed near the blue line. All values are approximated.as a function of