Brain calcium in the rabbit: site of action for the alteration of body temperature.

Body temperature was recorded in the unanesthetized rabbit during push-pull perfusion of regions of the hypothalamus. Both the anterior and posterior hypothalamus were perfused with physiological solutions containing Ca++ in a concentration 2.0 or 5.0 times that of extracellular fluid. The animals were placed in an ambient temperature of 4.0 +/- 2.0degrees C for at least 1 hr before the perfusion and all experiments were carried out at this temperature. In the posterior hypothalamic area Ca++ produced a sharp fall in body temperature but did not cause body temperature to alter when it was perfused through the anterior hypothalamic area. These results indicate that the rabbit is similar to the cat and monkey since the effect of Ca++ on body temperature is localized to the posterior hypothalamic region.