Haemorheology of the eastern grey kangaroo and the Tasmanian devil

Abstract

The blood of two Australian marsupials, the eastern grey kangaroo (Macropus giganteus) and the Tasmanian devil (Sarcophilus harrisii), has been reported to have greater oxygen-carrying capacity (i.e. haemoglobin content) when compared with that of placental mammals. We investigated whether alterations of blood rheological properties are associated with the increased oxygen-carrying capacity of these marsupials. Eastern grey kangaroos (n = 6) and Tasmanian devils (n = 4) were anaesthetised for blood sampling; human blood (n = 6) was also sampled for comparison. Laboratory measurements included blood and plasma viscosity, red blood cell (RBC) deformability, RBC aggregation and the intrinsic tendency of RBC to aggregate, RBC surface charge and haematological parameters. Scanning electron micrographs of RBC from each species provided morphological information. High-shear blood viscosity at native haematocrit was highest for the Tasmanian devil. When haematocrit was adjusted to 0.4 L L -1 , lower-shear blood viscosity was highest for the eastern grey kangaroo. RBC deformability was greatly reduced for the Tasmanian devil. Eastern grey kangaroo blood had the highest RBC aggregation, whereas Tasmanian devil RBC did not aggregate. The surface charge of RBC for marsupials was~15% lower than that of humans. The dependence of oxygen-delivery effectiveness on haemoglobin concentration (i.e. oxygen content) and blood viscosity was quantitated by calculating the haematocrit to blood viscosity ratio and was 15-25% lower for marsupials compared with humans. Our results suggest that environmental pressures since the marsupial-monotreme divergence have influenced the development of vastly different strategies to maintain a match between oxygen demand and delivery.

Physical Properties of Blood Are Altered in Young and Lean Women with Polycystic Ovary Syndrome

“…It was found that HVR for healthy women (CON) were comparable to earlier reports [18, 19], and women with PCOS presented with significantly decreased HVR at all shear rates (main effect p < 0.001). At the highest measured shear rates (750 and 1500 s -1 ), HVR was 8% lower in PCOS; the reduction became greater at 300 (10%), 150 (11%) and 75 s -1 (12%).…”

“…Haematocrit-to-viscosity ratio (HVR) was calculated for whole blood at native haematocrit by expressing haematocrit (%) to blood viscosity at each shear rate. The HVR has been explored as an index of oxygen delivery effectiveness of RBC based on the rationale that increased numbers of RBC is concurrently beneficial for oxygen transport, but also negatively increases blood viscosity, and therefore resistance to flow [18, 19]. …”

PoCOsteo: generic novel platform for bone turnover marker measurement & monitoring

“…Previous studies have shown the viscosity of WB, which is known to increase with aging, to vary between 5 and 120 mPa. 47 Using a chip resembling the microfluidic structure of the final cartridge, the coagulation risk of heparinized WB with various dilution factors was evaluated after a 30 min incubation period. Results revealed no clotting incidence in the 1 : 4 diluted heparinized WB samples as well as negligible effects on the LoD and LoQ of the OsteoLab using these samples.…”

Blood viscosity as a forgotten factor and its effect on pulmonary flow

“…Blood can carry the necessary nutrients to tissues and organs as long as it continues its normal flow pattern in the circulatory system. This normal flow is particularly important in the pulmonary vascular bed in order that gas exchange can be performed optimally [14–17]. Vessel constitution and the fluidity of blood need to be normal for normal blood flow [18, 19].…”