Uptake of Catecholamines by a Particulate Fraction of the Adrenal Medulla

Abstract

Chromaffin granules isolated from beef adrenal medulla took up C¹⁴-labeled catecholamines from an isotonic medium at 37°C at a rate approximately 20 times the rate at 0°C. The uptake was stimulated three- to five-fold by Mg⁺⁺ and adenosine triphosphate. Reserpine (1 x 10^-5M) caused a 90 percent inhibition of uptake; ethylenediaminetetraacetic acid completely inhibited the stimulation by magnesium and adenosine triphosphate, and the inhibition could be reversed by addition of excess Mg⁺⁺.