Towards a basic understanding of the properties of camel blood in response to exercise

Abstract

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 (WBV 500s -1 / WBV 11.6s -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 O 2 -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 O 2 transport at low shear areas by eventually preventing blood from becoming sluggish.

Near-Newtonian Blood Behavior – Is It Good to Be a Camel?

“…Training of horses raises also their resting RBC count (Dunstan et al, 2019), circumstances that bring more oxygen carriers into the bloodstream (Persson, 1983; Stoiber et al, 2005). But camels typically do not respond by an increase of the blood oxygen store (Auer et al, 2015), instead, they can even be in need of circulating RBCs (Tinson, 2017), especially when they are infected by blood parasites (Al-Hakak, 2017). Since the hematocrit has a major impact on blood viscosity, blood fluidity changes in horses during a race, but does not in camels.…”

“…The aggregation force between two neighboring cells is so high that even spiculated cells can be incorporated into a rouleaux formation (Baskurt et al, 1997). By contrast, the elliptic camel RBCs do not aggregate at all, which results in a low blood viscosity at low shear rates (Auer et al, 2015). The resting shape, the ability to withstand mechanical and osmotic stress, and intrinsic red cell properties reflect the diverse mechanical properties of camel and horse RBCs.…”