Effects of Mg²⁺ and Ca²⁺ on Noradrenaline Release and Uptake in Adrenergic Nerve Granules in Different Media

E uler , U. S. V. and F. L ishajko . Effects of Mg 2+ and Ca 2+ on noradrenaline release and uptake in adrenergic nerve granules in different media. Acta physiol. scand. 1973. 89. 415–422. Uptake and release of noradrenaline (NA) from a suspension of storage granules from bovine splenic nerves was measured after incubation in various media and effects of added Mg 2+ and Ca 2+ observed. No significant differences in NA release rate were observed in different media when NA uptake was prevented by addition of potassium ferricyanide to the medium. Uptake was facilitated by phosphate ions 5–30 mM but counteracted by monovalent cations. In sucrose‐phosphate media uptake of NA almost balanced spontaneous release. Mg 2+ and Ca 2+ had only a small action on NA release in the absence of NA uptake. In sucrose phosphate media Mg 2+ facilitated uptake, whereas Ca 2+ enhanced NA release. This action was associated with the formation of a calcium phosphate precipitate. No release or uptake of NA was observed during incubation at ice‐water temperature, nor did Mg 2+ or Ca 2+ have any effect. The results tend to show that release and uptake of NA in storage granules are separate, temperature‐dependent processes, influenced by mono‐ and divalent cations and phosphate ions.