Whole blood viscosity, plasma viscosity and erythrocyte aggregation in nine mammalian species: reference values and comparison of data.

This research article examines the varying rates of blood viscosity, plasma viscosity, and red blood cell aggregation in nine different mammalian species. The species included animals such as horses, pigs, dogs, cats, rats, and mice among others. Each species exhibited unique viscosity and aggregation parameters which are denoted as its rheological fingerprint.

Methodology and Species Involvement

• The researchers carried out their study on a total of 360 adult animals. These included 40 individual animals from each species – horse, pig, dog, cat, rat, cattle, sheep, rabbit, and mouse.
• Using different equipment such as the LS30 viscometer, OCR-D, and Myrenne aggregometer, they measured the whole blood viscosity (WBV), plasma viscosity (PV) and erythrocyte aggregation (EA).

Key Findings

• The findings indicated that at low shear rates, samples standardized for hematocrit showed higher values of WBV and EA in horses, pigs, dogs, and cats. In contrast, cattle, sheep, rabbits, and mice showed significantly reduced EA and WBV, with EA being nearly undetectable despite a higher plasma fibrinogen concentration in these animals.
• Interestingly, rats had the highest WBV at low shear rates, similar to horses when analyzing standardized blood. However, their EA was extremely low, which might be due to the mechanical or geometrical characteristics of the rats’ red blood cells.

Species-Specific Correlations and Differences

• The researchers observed correlations between EA and plasma protein concentration in every species except dogs and mice. Additionally, in species such as horses, cattle, and pigs, there seemed to be a correlation between EA and plasma fibrinogen concentration.
• When it came to high shear rates, cattle had a higher WBV than cats and rats, while dogs exhibited higher values than horses. These interspecies differences may result from particular mechanisms influencing red blood cell flexibility.
• As for plasma viscosity, which did not correlate with WBV, it was highest in cattle, and lowest in rabbits and mice.
• In summary, each studied species exhibited different haemorheological parameters, signalling unique “rheological fingerprints”.

How this Impacts Future Research and Understanding

• This research supports the theory that factors influencing flow-mediated endothelial cell signal transduction may vary among species due to distinctive haemorheological parameters.
• However, exactly how these differences in blood viscosity and cell aggregation contribute to endothelial cell shear stress is yet to be determined.
• These findings lay important groundwork for further research into the physiological significance of these variations among mammalian species.