AJP - Regulatory, Integrative and Comparative Physiology, Vol 239, Issue 3 248-R253, Copyright © 1980 by American Physiological Society
Temperature dependence of blood viscosity in frogs and turtles: effect on heat exchange with environment
B. L. Langille and B. Crisp
The temperature dependence of the viscosity of blood from frogs and turtles
has been assessed for temperatures between 5 and 40 degrees C. Viscosity of
turtles' blood was, on average, reduced from 3.50 +/- 0.16 to 2.13 +/- 0.10
cP between 10 and 30 degrees C, a decline of 39%. Even larger changes in
viscosity were observed for frogs' blood with viscosity falling from 4.55
+/- 0.32 to 2.55 +/- 0.25 cP over the same temperature range, a change of
44%. Blood viscosity was highly correlated with hematocrit in both species
at all temperatures. Viscosity of blood from both frogs and turtles showed
a large standard deviation at all temperatures and this was attributed to
large individual-to-individual variations in hematocrit. Turtles heat
faster than they cool, regardless of whether tests are performed at
temperatures above or below the range of thermal preference. The effect of
temperature dependence of blood viscosity on heating and cooling rates is
demonstrated.
