THE INTRINSIC REGULATION OF THE BLOOD VESSELS OF THE MEDULLA OBLONGATA

Abstract

By means of a small cooled thermocouple inserted through the occipito-atlantoid space, changes in blood-flow were estimated qualitatively in the medullas of cats under amytal narcosis or decere-brated; curarization or high cord transection was used to obviate artifacts. No potent vasomotor innervation was detected by stimulation of cervical sympathetic, vagodepressor, carotid sinus, or perivertebral nerves. A marked chemical regulation was regularly present, CO2 apparently playing a specific role. It is suggested that medullary vessels normally have a high intrinsic tone that is variably antagonized by vasodilator hormones of which CO3 is outstanding; this apparently constitutes the sole intrinsic regulation of the medullary circulation.