Central control of sympathetic cardiac augmentation in lower brain stem of the cat

Abstract

Fifty-three vagotomized cats under chloralose were studied for cardiac augmentation, cardioacceleration, and vasomotor reaction on direct stimulation of the medulla oblongata and via reflex activations. Cardiac augmentation as well as other cardiovascular responses could be induced on stimulation of the dorsal medulla or the central cut end of the sciatic nerves, or on occlusion of the carotid arteries. The augmentation and other responses remained essentially unchanged regardless of the presence or absence of the rostral neural structures, including the hypothalamus. The results confirm and support the concept that a central control mechanism for vasomotor reaction and cardioacceleration as well as augmentation resides in the dorsal region of the lower brain stem.