Effect of magnesium on calcium efflux in dialyzed squid axon.

The Ca efflux mechanism located in the axolemma of the tropical squid Doritheutis plei is shown to be affected by the concentration of intracellular Mg (Mgi). The removal of all of the Mg from the experimental preparation causes an increase in Ca efflux. This effect seems to be more pronounced at low levels of internal ionized calcium and high levels of internal Na.