Abstract
The release of adrenaline from the adrenal medulla of the mouse under conditions of insulin shock and inanition and the release of noradrenaline under conditions of cold stress have been demonstrated. Associated with the release of both adrenaline and noradrenaline is the development of high levels of alkaline phosphatase activity in the secreting cells. These observations support the following conclusions: (a) the cells containing materials demonstrable by potassium iodate oxidation are true noradrenaline-secreting cells and do not represent secretory phases of a common cell type; (b) the association of increased alkaline phosphatase activity with release of adrenaline or noradrenaline is probably indicative of increased secretory activity.