394 BIOCHIMICA ET BIOPHYSICA ACTA VOL.'23 (1957) THE INFLUENCE OF SOME CATIONS ON AN ADENOSINE TR IPHOSPHATASE FROM PERIPHERAL NERVES

Stimulation of a nerve leads to an influx of sodium ions into the fibre and hence to an increase in the intra-axonal sodium concentration 1. Normal conditions are restored by an outward transport of the sodium ions, and this process requires energy because the etttux takes place against an electrochemical gradient. The mechanism of this transport is not known. In experiments with giant axons from Sepia o~cinalis and from Loligo/orbesi, HODGKIN AND KEYNES 2 found that dinitrophenol, azide and cyanide inhibit the active transport of sodium ions out of the nerve; this inhibition is reversible. In the concen-trations used all three substances also inhibit the oxydative phosphorylation which takes place in mitochondria; dinitrophenol and azide do so through an uncoupling of the phosphorylation 3, ~, and cyanide through an inhibition of the oxydation ~.CALD-WELL 6 observed correspondingly that addition of these substances, in the concentra-tions used by HODGKIN AND KEYNES, led to a reduction of the content of energy-rich phosphate sters in the axoplasm of giant axons. This seems to indicate that energy-rich phosphate esters are somehow involved in the active transport of sodium ions ou