SCREEN FILTRATION PRESSURE OF HOMOLOGOUS AND HETEROLOGOUS BLOOD AND ELECTROENCEPHALOGRAM.

Abstract

The character and duration of electrical activity arising from a completely isolated cat's head was dependent upon the screen filtration pressure (SFP) of the heparinized oxygenated blood with which it was perfused. If the SFP was above normal the amplitude and frequency of the EEG first decreased, then the brain waves disappeared. The duration of time from the beginning of perfusion until these changes in the EEG occurred was inversely related to the SFP of the perfused blood. Also, the perfusion rate was inversely related to the SFP provided the perfusion pressure remained the same. It is believed that the increase in SFP and changes in EEG and blood flow were due to the presence in the blood of aggregates of blood cells (platelets and leucocytes) which obstructed the brain capillaries. It would appear that heterologous (dog) as well as homologous (cat) blood can be effectively used to perfuse the isolated cat's head provided the blood has a normal SFP. In practice, this was made possible by filtering the blood continuously through Pyrex glass wool.