Data presented were from one dog in the CS group. (A) The results from the length-dependent activation experiment show strong linear correlation between CR rates, with a Pearson coefficient of R² = 0.981. (B) The results from the frequency-dependent activation experiment show a strong linear correlation for CR, R² = 0.993. (C) These data show that the results of the isoproterenol dose–response experiment have a strong linearity, with R² = 0.997. (D) Combination of all three experiments into one plot showing a tight linear correlation for all cardiac output regulatory mechanisms at R² = 0.965. Linear regression and Pearson correlation coefficient are calculated as shown.