The independence of membrane potential and potassium activation of the sodium pump in muscle.
The membrane potential (Em) of sartorius muscle fibers was made insensitive to [K+] by equilibration in a 95 mM K+, 120 mM Na+ Ringer solution. Under these conditions a potassium-activated, ouabain-sensitive sodium efflux was observed which had characteristics similar to those seen in muscles with Em sensitive to [K+]. In addition, in the presence of 10 mM K+, these muscles were able to produce a net sodium extrusion against an electrochemical gradient which was also inhibited by 10- minus 4 M oubain. This suggests that the membrane potential does not play a major role in the potassium activation of the sodium pump in muscles.
D000818:Animals; D001001:Anura; D006614:Hindlimb; D008564:Membrane Potentials / Q000187:drug effects*; D009132:Muscles / Q000378:metabolism / Q000502:physiology*; D009994:Osmolar Concentration; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology*; D012964:Sodium / Q000378:metabolism*
D010042:Ouabain; D012964:Sodium; D011188:Potassium