BLOOD VISCOSITY UNDER DIFFERENT EXPERIMENTAL CONDITIONS AND ITS EFFECT ON BLOOD FLOW

Abstract

By means of a simple viscometer (in which duplicate detns. agree within 5%) the specific viscosity of blood has been detd. empirically in normal unanesthetized dogs and in dogs after the induction of exptl. procedures preliminary to the measurement of blood flows. In normal dogs, the specific viscosities varied from 7.1-3.7. Blood defibrination, the addition of heparin (in vitro or in vivo) and the inj. of morphine sulphate do not affect the viscosity. Hemorrhage (after a short period) and barbital anesthesia caused considerable reduction in viscosity; a decrease in blood temp. increased viscosity, while ether anesthesia, the in vitro use of Na citrate, and the in vitro or in vivo use of pontamine fast pink (or chlorozol fast pink) gave large increases in viscosity. In general these changes in viscosity were directly related to the hematocrit. However, in the case of pontamine fast pink and sodium citrate added to drawn blood the effects were reversed. Expts. show that these changes are sufficient to alter greatly the facility with which blood flows through vascular beds of the anesthetized dog or through perfused organs.