The importance of calcium in the release of catecholamine from the adrenal medulla.

Recently, the mechanisms of storage and release of catecholamine in various tissues have become a topic of interest. The present study is on the mechanism of release of catecholamine from the adrenal medulla in an in vitro system. The adrenal medulla seems to provide a suitable system for such an in vitro study, because it contains large amounts of catecholamine in chromaffine granules, about which is much information available (1-8). Substances known to alter membrane permeability, namely excess potassium ion and acetylcholine were examined. The effects of tyramine and reserpine, drugs which deplete tissue stores of catecholamine were also examined with this system. A preliminary report of part of this work has been published (9).