Plasma volume after dextran infusion in rats sensitive and non-sensitive to dextran.

Plasma volume determinations were done with RIHSA under normal conditions and after intravenous infusion of dextran solutions. The plasma volume of normal rats in millilitre was found to be 0.026 X body weight + 0.92. Infusion of dextran into dextran-sensitive Sprague-Dawley rats was followed by a marked plasma volume reduction and haemoconcentration as consequence of an anaphylactoid reaction. This reaction could be partially inhibited by pretreatment with cyproheptadine chloride. Plasma volume determination with the method used in this study can be used to evaluate the dextran-anaphylactoid reaction. In dextran non-sensitive Wistar rats, infusion of dextran had a strong plasma volume-expanding effect comparable to the plasma volume-expanding effect of dextran in humans. No signs of abnormal leakage of fluid out into the extravascular space were evident, which indicated that the Wistar rats really were non-sensitive to dextran.