EFFECT OF TEMPERATURE AND METABOLIC INHIBITORS ON 45CA OUTFLOW FROM SQUID GIANT AXONS

Labelled Ca2+ were incorporated into giant axons from the squid Dosidicus gigas by immersing them in sea water containing 45Ca2+. This washout technique was used and two kinetics for 45Ca2+ outflow were demonstrated (time constants of 0.140 and 0.005 min-1, respectively). The second kinetics of 45Ca2+ outflow was greatly affected by temperature and by some metabolic inhibitors. Lowering the temperature of the external sea water resulted in a reduction of the outflow and addition of uncouplers of oxidative phosphorylations or electron transfer inhibitors to the sea water induced an increase in the outflow. Ouabain, at a concentration which has been shown to effectively inhibit Na+ efflux from axons of the same species, does not affect the seocnd kinetics of 45Ca24 outflow. It is claimed here that this second kinetics is related to an intra-axonal compartment and that the rate of this Ca2+ outflow is determined by a steady state of calcium uptake and calcium release by some intra-axonal structures. © 1968.