Abstract
The quantitative contribution of the adrenal medulla to the pressor response resulting from stimulation of the entire preganglionic sympathetic spinal outflow of the rat, has been estimated. Adrenalectomy reduced the pressor responses not only to preganglionic nerve stimulation but also to injected noradrenaline. This reduction in cardiovascular sensitivity occurred within about 10 min of adrenalectomy and continued throughout the course of each experiment. Intramuscular injection of cortisone (20 mg/kg) restored cardiovascular sensitivity to injected noradrenaline thus allowing analysis of the adrenal medullary component of the overall response to spinal nerve stimulation.