The effect of dehydration on macro- and microrheological blood properties

It is known that intensive physical activity causes a loss of water. Since physical capacity is highly dependent upon fluidity of blood, the rheological characteristics of which are largely determined by water content, the aim of our study was to estimate rheological properties of blood under dehydration. To model the state of dehydration, the water deprivation was performed on rats (n=49) for 3 and 10 days. We registered hematocrit, apparent plasma viscosity; apparent viscosity, rigidity index (Tk), structural parameter (k), and extent of aggregation ("M" and "M1" indices) were determined in both unfractionated and density separated RBC suspensions in autologous plasma at Ht=40. The Ht/viscosity ratio as index of oxygen supply to tissues was calculated. The results of our study indicated that water deprivation caused progressive reduction of blood and plasma fluidity. The increase of Ht (22%, p<0.001) and significant elevation of erythrocyte aggregation (205%, p<0.001) were observed. In spite of Ht increase, oxygen transport was decreased by 18% (p<0.05). RBC rigidity was increased under water deprivation (13.6%, p<0.05) as well as during aging. Significant correlation was found between indices of aggregation and Tk and k indices in the course of dehydration. Thus, our data indicated that dehydration caused impairment of blood and RBC rheological properties.