Blood and plasma viscosity of winter flounder: influence of temperature, red cell concentration, and shear rate

Abstract
The effects of temperature, red cell concentration, and shear rate on the viscosity of blood from the winter flounder (Pseudopleuronectes americanus) were evaluated using a cone-plate viscometer. The viscosity of blood and plasma was shear rate dependent at all temperatures studied (−1 to 20 °C) with the highest values occurring at the lowest temperature and shear rate. At normal hematocrits (20%), plasma appeared to account for at least 50% of the total blood viscosity. The effects of hematocrit on viscosity were dependent on temperature. At higher temperatures (10–20 °C), increases in hematocrit resulted in a near-exponential increase in viscosity. At lower temperatures (5 °C) and shear rates (4.5 s−1) no significant increase in viscosity occurred between hematocrits of 11 and 43%. The influence of temperature and shear rate on blood viscosity suggest that winter flounder may have to contend with a fivefold increase in blood viscosity when acclimating from summer to winter water temperatures.