CAPACITY FOR RED-BLOOD-CELL AGGREGATION IS HIGHER IN ATHLETIC MAMMALIAN-SPECIES THAN IN SEDENTARY SPECIES

The purpose of this study was to show that two theological parameters, red blood cell (RBC) sedimentation rate and apparent blood viscosity at low shear rate, characterizing the degree of RBC aggregation, corre late significantly with the maximal mass-specific rate of oxygen consu mption or aerobic capacity (Vo(2max)). Comparisons were made within tw o groups of similarly sized athletic and sedentary species: group 1, p ronghorn antelope, dog, goat, and sheep; and group 2, horse and cow. T he pronghorn antelope (Antilocapra americana) is one of the most athle tic mammals, and we have obtained data on the theological properties o f blood from this species for the first time. The values of apparent v iscosity at hematocrit = 40% and shear rate = 0.277 s(-1) measured in a rotational viscometer were 59.5, 42.6, and 9.1 cP for antelope, dog, and sheep blood, respectively, and 55.3 and 11.5 cP for horse and cow blood, respectively. The viscosity values for antelope, dog, and shee p blood can be correlated with aerobic capacity: In viscosity = 4.48 - 106.3 Vo(2max)(-1) (r(2) = 0.998; P < 0.05). The values of RBC sedime ntation rate at hematocrit = 40% were 12.8, 7.0, and 0 mm/h for antelo pe, dog, and sheep blood, respectively, and 45.3 and 0.1 mm/h for hors e and cow blood, respectively. Therefore, the data showed that the ath letic species exhibit a consistently higher degree of RBC aggregation than do the corresponding nonathletic species.