Determination of blood volume in anaesthetized rat using the
Evans Blue method
Authors :
Véronique Lullier, Malorie Privat

Abstract
Blood is well known as a vital liquid of living beings. This article deals with the Evans Blue method used to assess blood volume in a rat model. The first step consists in injecting a measured quantity of Evans Blue dye directly in the jugular vein. After a mixing phase, a sample of blood with diluted dye is collected in the carotid vein. The plasma collected after blood centrifugation is used for a spectrophotometric analysis. In a second step, an hematocrit has been carried out by centrifuging another blood sample. The measured haematocrit values were used for calculation. Thus, the factor of dilution, which is correlated to the blood volume, can be determinated by means of a standard curve (r² =0,992). This curve is built by measuring the absorbance of different dye dilutions. The calculation gives a blood volume equal to 17,2 ml +/- 2,7ml ie. 4,0% of the rat mass.
This result is consistent with the usual values found in the litterature (2;3;4). As this method is relatively harmless, it could be adapted for human's body investigations.

Introduction
Blood is a liquid connective tissue, that circulates in the body of most living beings, by means of a network of blood vessels.
Blood has a vital function since it is involved in respiration, nutrition, thermoregulation of warm-blooded animals. It controls homeostasis parameters and participates in cellular defense. In this study, our goal is to assess the blood volume in an anaesthetized organism using a reliable method. To this effect, we used a specific non-toxic dye : The Evans Blue. This method is quick, and allow a good estimation of the blood volume. The results of our calculations seem consistent with those found in the literature. Moreover, it could be used directly in a living organism without

life-threatening. Indeed, in our rat, we