The effects of elevated potassium on sympathetic ganglion cells in culture

Effects of a high potassium (40 mM) medium on the survival and differentiation of sympathetic ganglion cells from chick embryos were studied in dissociated cell culture. In the high potassium medium, survival of the sympathetic ganglion neurons was improved and catecholamine fluorescence of the nerve fibers increased with several days in culture, while acetylcholinesterase activity was slightly positive. In contrast, in the control medium, catecholamine fluorescence was only faintly observed, while acetylcholinesterase became strongly positive. Catecholamine fluorescence was intensified by increasing the potassium concentration in a medium, while it was diminished by reversing the potassium level back to the normal one. The effect of the high potassium medium on catecholamine fluorescence was reduced by Ca++ influx inhibitors, diltiazem or Mg++. It is suggested that the high potassium medium increased the survival rate and prevented the sympathetic neurons from becoming cholinergic and allowed them to develop their adrenergic properties presumably through an increased level of the intracellular Ca++ due to Ca++ entry.