The relationship between plasma Epo and Hb in peripheral blood in female rats at 8 weeks with various degrees of bleeding. • indicates no bleeding (n = 9); ⬡, 1-mL bleeding (n = 8); and ○, 2-mL bleeding (n = 7). The regression equation and correlation coefficient of the regression line are y = 13 255e^-0.5172x and 0.871, respectively.