No abstract

A new method for studying adrenal medullary release is described in pithed rats using field stimulation of an entire adrenal gland. The increases in blood pressure in response to field stimulation of the gland consisted of an initial short, variable component, due to stimulation of adrenergic vasomotor neurones and a secondary, longer lasting component, due to medullary catecholamine release. Removal of the initial component by drugs or cardiac/coeliac ganglionectomy did not affect the magnitude of the secondary pressor component. The secondary pressor component was frequency‐dependent, reproducible and stable with time. The extent of medullary catecholamine release could be assessed by comparing the blood pressure rise with those obtained after adrenaline injections. The method appears to provide a reliable means by which adrenal medullary catecholamine release may be assessed without significant interference from vasomotor nerves.