Perfusion from cerebral ventricle to cisterna magna in the unanaesthetized cat. Effect of calcium on body temperature.

1. A method is described for the perfusion of the liquor space from a lateral cerebral ventricle to the cisterna magna in the unanaesthetized cat. Perfusions were carried out for 30-40 min using various physiological salt solutions whilst rectal temperature was recorded.2. When the salt solution used contained calcium in the physiological concentration, rectal temperature remained unchanged, but when it contained no calcium an intense hyperthermia developed during the perfusion. The finding that calcium must be present in the perfusion fluid for preventing temperature from rising may lead to a new understanding of the working of the ;set-point' in the control of body temperature and of the mechanism of action of pyrogens.3. Independent of the nature of the perfusion fluid a long-lasting late rise in temperature developed after a perfusion. This happened regularly when the infusion needle was inserted only into the hub of the ventricular cannula, but rarely when the needle was extended beyond the tip of the cannula shaft and the cannula had been flushed out during the preceding days. It is therefore thought that an unknown pyrogenic factor present in the lumen of the cannula and washed into the ventricle with the perfusion fluid is responsible for this effect.4. The effluent collected from the cisterna contracted the fundus strip of the rat stomach. As the contractions were little affected by BOL, they are attributed mainly to an action of prostaglandin E(1) and not to an action of 5-HT. There was no difference in the biological activity of the effluent whether the perfusion fluid contained calcium or not.