Effects of alkali metal and other monovalent ions on the adrenomedullary secretion

Abstract

The effects of alkali metal ions, ammonium and quaternary ammonium ions on the release of catecholamines were studied in the perfused adrenal glands of rabbits. An immediate secretory response was caused by high concentrations of Rb + or Cs + as well as K +, but not by Na + or Li +. This response was apparently due to their depolarizing effect which is generally observed in excitable tissues. High doses of NH 4 + also evoked catecholamine secretion but in two phases; an early response quite similar to that with alkali metal ions which was followed by a Ca ++-independent discharge which was probably due to a toxic effect on the chromaffin cells. Some of the quaternary ammonium ions, on the other hand, produced an immediate secretory response (the ‘on’ response) and in addition an increase in catecholamine release was observed just after perfusion with high concentrations of these ions had ceased (the ‘off’ response); the mechanism of the latter effect remains to be elucidated although influx of Ca ++ may be responsible.