Figure 2.

Dose-response curve for ATP on the isolated working rat heart preparation. (a) The relative change in TCR is plotted against [ATP]. TCR was calculated as (TCR_pretreatment−TCR_{posttreatment})/TCR_pretreatment×100%. TCR_pretreatment refers to the 15th minute of the control period. TCR_{posttreatment} refers to the 5th minute of the treatment period. (b) Transformed data used to determine the apparent ATP concentration that resulted in a 50% change in TCR. Linear regression analysis gave a straight line with r²=0.7893; b(0)=57.238; b(1)=−2.4175. Dashed lines represent 95% confidence interval.