Model of elevated hematocrit in mice. RBCs from “donor” mice were injected into “recipient” mice (RBCHIGH) via retroorbital plexus. After 24 hours, blood was drawn from RBCHIGH and control (uninfused) mice. Complete cell counts indicate (A) elevated hematocrit, but normal (B) neutrophil, (C) monocyte, and (D) platelet numbers. In panels A-D, each dot is a separate mouse; lines indicate median values, and boxes represent the normal range. (E) Blood smears (Diff-stain kit [IMEB, San Marcos, CA], imaged on an Olympus BX71 at ×40 and digitally zoomed) of washed RBCs and whole blood from control and RBCHIGH mice indicate normal RBC morphology. (F) Flow cytometry indicates normal phosphatidylserine exposure on washed RBCs and RBCs isolated from control and RBCHIGH mice. Bars indicate mean ± SD, N = 3. (G) Viscosity measurements show RBCHIGH mice (closed circles) have significantly increased viscosity (Pascal-seconds, Pa.s) at low and high shear compared with control mice (open circles). Symbols show mean ± SD, N = 3-5 per group.