EFFECT OF CARBON DIOXIDE ON BLOOD FLOW VELOCITY IN THE ARTERIOLE OF CAT'S CEREBRAL CORTEX

Publisher Summary Oxygen supply to cerebral cortex increases in response to carbon dioxide, which has a remarkable cerebral vasodilatory action. It is unknown if the blood flow velocity increases when carbon dioxide is locally increased. This chapter discusses a study to examine the effect of carbon dioxide on blood flow velocity in the arteriole of cat's cerebral cortex. Adult cats were anesthetized by i.p. nembutal 30 mg/kg and i.p. urethane 1 g/kg. The right hemisphere of the brain was exposed by cutting the skull and dura mater roundly. A plastic ring was fixed to the round hole so as to gently push the brain tissues. The oscillation of the brain tissues due to the cardiac contraction could be markedly reduced by the light compression of marginal portion of the exposed cerebral tissues by the ring. The local application of carbon dioxide increased both the blood flow rate and velocity. It is found that although the pulsatile flow in microvessels deviates from a parabola profile, it may be expressed as a Poisueille flow for a first order approximation. It is observed that if only the diameter is changed by the carbon dioxide application, the mean flow velocity changes in proportion to the square of the diameter of the vessel.