SIMILARITIES IN THE ACTIONS OF POTASSIUM AND CALCIUM IONS ON GANGLIONIC AFTERPOTENTIALS

¹ Department of Pharmacology, Tulane University School of Medicine, New Orleans, Louisiana

Calcium chloride caused depolarization, an increase in the negative afterpotential (NAP) and a decrease in the positive potential and positive afterpotential of the cat's superior cervical ganglion. Initially, potassium chloride caused a decrease in the NAP and positive afterpotential and an increase in the positive potential. During the falling phase of depolarization by potassium, the NAP was increased and the positive potential and positive afterpotential were decreased. In contrast to their effects on the NAP, calcium and potassium had opposite effects on the synaptic potential. Whereas calcium caused a marked increase in the synaptic potential,potassium (and barium) caused a decrease in the potential.