The objective of the study was to investigate changes in blood fluidity in camels in response to exercise. 11 camels (9 male, 2 female) performed a 30 minutes run. Blood lactate changes indicated mild aerobic exercise. HCT and PCV remained essentially unchanged while plasma protein concentration decreased mildly suggesting a gain in blood volume of 1-2 L. Whole blood viscosity (WBV) did not change significantly at any shear rate (flow curves at logarithmic shear rate (SR) ramp, 37°C:11.6-500 s-1), and viscosity ratio (WBV500s-1/ WBV11.6s-1) was maintained as well. RBC aggregation indices M0 and M1 did not change significantly either. The theoretical optimal HCT, i.e. the range of the HCT at which the O2-transport capacity (HCT/WBV) is highest, was estimated by measuring WBV of RBC dilutions in autologous plasma. The RBC concentrations were measured as PCV and thus PCV/WBV plotted against PCV (2nd degree polynom). At 11.6 s-1 the “optimal HCT” was at a PCV of 49.2%, and decreased to 34.8% at 500 s-1. In arteries and arterioles (high SR), the actual PCV observed may be regarded “optimal”, whereas in venules and veins (low SR), the actual PCV observed was lower than its theoretical “optimal” value. This indicates that a possible increase in PCV might provide a sizable reserve in performance capacity. During a more strenuous exercise or at arid environments this would optimize O2 transport at low shear areas by eventually preventing blood from becoming sluggish.
Key words: Blood viscosity, Camel, Exercise, Hemorheology, Optimal hematocrit
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