Metabolism and transport of strontium in giant axons of Loligo.

1. The strontium content of squid axons averages 2.9 mumol kg-1 axoplasm and squid blood contains 75 mumol Sr l-1. The bulk of the Sr inside axons is bound, possibly within mitochondria. Sr seems to be handled by squid axons in an essentially similar manner to Ca. 2. Sr uptake is increased by electrical activity, by lowering external Na, by depolarization with K and by poisoning with cyanide or FCCP. Uptake is unaffected by ouabain. 3. Sr efflux has a Q10 of 2.2. Efflux can be divided operationally into three components: one dependent on external Ca (or Sr), one dependent on external Na and a residual component that can be inhibited by external lanthanum or internal vanadate. 4. Poisoning an axon with cyanide or FCCP results in a large increase in Sr efflux which can be divided operationally into two components: one dependent on external Ca (or Sr) and one dependent on external Na.