D2O and the sodium pump in squid nerve membrane.
In 10 K artificial seawater (ASW), D2O replacement reduced the Na efflux of squid axons by about one third. In 0 K ASW, D2O replacement had little effect. D2O reduced the K+ sensitivity of the efflux but increased the affinity for K+. A 4 degrees decrease in temperature mimicked the effects of D2O. When axons were injected with arginine, to decrease the ATP/ADP ratio, they lost K+ sensitivity in normal ASW, as expected. Their efflux into 0 K ASW became D2O sensitive. The results are discussed in terms of conformational changes in the Na pump molecular complex.
D000818:Animals; D002462:Cell Membrane / Q000201:enzymology*; D049832:Decapodiformes; D003903:Deuterium; D017666:Deuterium Oxide; D008954:Models, Biological; D009474:Neurons / Q000201:enzymology*; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D014867:Water
D014867:Water; D012964:Sodium; D003903:Deuterium; D000254:Sodium-Potassium-Exchanging ATPase; D017666:Deuterium Oxide