Figure 4.

(A) Viscosities of fresh and aged red blood cells. Viscosity was found by multiplying the efflux time by the shear rate provided with the viscometer. The average viscosities for fresh and older blood were 7.8 ± 0.8 cSt and 10.5 ± 1.8 cSt, respectively (P = 0.015). (B) Effects of saline infusions at different flow rates. The % change from baseline of flows for saline increased as the rate of flow increased at 5, 10, and 15 ml per hour. The % changes from baseline for saline at all infusion rates are lower than that of blood or acetylcholine infusions but do show that higher intraarterial infusion rates produce shear-related increases in blood flow. cSt = centistokes; NS = normal saline.