Adenosinephosphates and Inorganic Phosphate in the Adrenaline and Noradrenaline Containing Granules of the Adrenal Medulla

Summary. 1. The catechol amine containing granules of the cow adrenal medulla have been isolated as a fraction of high purity by density gradient centrifugation. They have a very high content of amines (34.3 μmoles/mg protein‐N) and ATP (7.6 μmoles). Smaller amounts of ADP (0.89 μmoles), AMP (0.27 μmoles) and inorganic phosphate (1.45 μmoles) are also present. The adenosinephosphates represent at least 95 per cent of the acid soluble organic phosphates in the granules. 2. The molar ratio amines: ATP is 4.5: 1 or 3.9: 1, if the ADP and AMP in the granules are assumed to be split products from ATP. The sum of adenosinephosphates and inorganic phosphate represents an amount of acid equivalent to the catechol amines. This suggests that the amines are stored in intimate relation to the phosphates. 3. The osmotic properties of the granules and the amine content found in them make it necessary to assume that the amines are incorporated, together with the adenosinephosphates, in a complex molecular structure which prevents them from forming free ions or molecules in the intragranular water. The presence of large amounts of water soluble proteins (77—78 per cent of the total proteins) within the granules suggests that these proteins are a component in the postulated structure.