Vanadate selectively inhibits the Ko+-activated Na+ efflux in squid axons.
The effects of internally applied 1 mM vanadate on the Na+ efflux in dialysed squid axons were found to depend on the presence of external K+. In K+-free artificial sea water, vanadate did not produce any change in the rate of Na+ efflux, whereas in the presence of 10 mM K+ the Na+ efflux was reduced to values even lower than those observed in the absence of K+ (inversion of the K+-free effect). In vanadate-poisoned axons, K+ and NH+4 at low concentrations activated Na+ efflux, but at high concentrations both cations were inhibitory. However, NH+4 was always a better activator and a poorer inhibitor than K+.
D000641:Ammonia / Q000494:pharmacology; D000818:Animals; D001369:Axons / Q000187:drug effects / Q000378:metabolism*; D049832:Decapodiformes; D007700:Kinetics; D011188:Potassium / Q000494:pharmacology*; D012964:Sodium / Q000378:metabolism*; D014639:Vanadium / Q000494:pharmacology*
D014639:Vanadium; D000641:Ammonia; D012964:Sodium; D011188:Potassium