Blood pressure responses to adrenal field stimulation as a measure of adrenal catecholamine release.

1 A new method for studying adrenal medullary release is described in pithed rats using field stimulation of an entire adrenal gland. 2 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. 3 Removal of the initial component by drugs or cardiac/coeliac ganglionectomy did not affect the magnitude of the secondary pressor component. 4 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. 5 The method appears to provide a reliable means by which adrenal medullary catecholamine release may be assessed without significant interference from vasomotor nerves.