Drug Effects on Epineprine Release from Rat Adrenal Medulla Homogenates and Granule Preparations.

Summary1. Adrenal homogenates and fractionated medullary granule suspensions from rats were incubated in various media at several temperatures with and without addition of various concentrations of drugs, after which adrenaline concentration was measured in the centrifuged particulates and the supernatant. 2. Both homogenates and granule suspensions showed minimal spontaneous release of adrenaline at O°C, markedly increased with temperature. All drug incubations were carried out routinely at O°C. In many instances determinations were repeated at increased temperature and drug concentration under experimental conditions which approximated those of other investigators who studied the release of catecholamines from the chromaffin granules of other species. 3. Thirteen of the 35 drugs examined modified the release of adrenaline from the rat chromaffin granules. a) Ten of these were previously reported to increase the release in vitro in other species. They were chlorpromazine, compazine, CH3-promazine, chlorp...