Some Observations on the Synthesis and Storage of Catecholamines in the Adrenaline Cells of the Suprarenal Medulla

Abstract

AbstractThe intracellular distribution of dopamine, noradrenaline and adrenaline in rabbit suprarenal glands was examined by differential centrifugation of homog‐enates (0.3 M sucrose) of the medullary tissue. The amines were determined spectrophoto‐fluorimetrically.Glands from normal animals were found to contain no — or very small — amounts of dopamine and noradrenaline. When the medulla was stimulated to secretion by insulin‐induced hypoglycemia, noradrenaline was rapidly formed. It accumulated in the “large granule” fraction, but largely disappeared together with the adrenaline store on prolonged stimulation. Large amounts of “bound” noradrenaline again accumulated during the recovery phase.Very large amounts of dopamine and noradrenaline rapidly (within 30 min) appeared after an intravenous injection of L‐dopa (100 mg/kg body wt). The new‐formed amines became rapidly “particle‐bound”. In contrast to dopamine which largely disappeared after some hours the noradrenaline remained in large amounts for at least 24 hours.A tentative scheme of the intracellular events which occur when the adrenaline cell synthesizes and stores catecholamines is proposed and discussed.