Comparison between tail skin blood flow measurements by ultrasonic Dopplerflowmetry and plethysmography during heating in anesthetized rats

Tail skin blood flow (TBFu) was directly measured in anesthetized and passi vely heated rats by ultrasonic Doppler flowmetry during heating, and the va lues were compared to those (TBFp) simultaneously measured by venous-occlus ion plethysmography. TBFp was estimated from the values per unit tissue mul tiplied by the tail volume, the shape of which was assumed to be a cone. TB Fp was highly correlated with TBFu, with a regression equation of TBFp=0.7T BF(u)+0.1 (r(2)=0.94, p<0.001). Although TBFp was slightly lower than TBFu, the equation is useful to estimate the absolute values of tail skin blood flow from the values of plethysmography in awake rats.