Fig. 4.

Pharmacodynamic effects of chimeric activator variants on reticulocytes, hematocrit, and total platelets. (A) huGYPA transgenic mice received a single i.p. injection of darbepoetin, 10F7-EPO variant, or saline at the indicated concentrations (1 pmol darbepoetin = 37 ng; 1 pmol 10F7-EPO variant = 72 ng). Blood was obtained by tail-nick on days 0, 4, 7, and 11; the bar graphs indicate day 4 measurements. Measured parameters were reticulocyte fraction of whole blood by flow cytometry (B–F), and hematocrit (G–K) and total platelet counts (L–P) by hematology analyzer. Measurements were baseline-subtracted relative to day 0. Graphs display mean ± SEM (n = 4). Comparisons between treatments were done using Student’s t test. *P < 0.1; ***P < 0.005.