925681 ENa equilibrium potential 11 925682 ENa electromotive force of the active Na current 3 925678 ENa exchangeable sodium 3 925679 ENa erythrocyte Na 2 925684 ENa electromotive force of Na+ transport 1 925683 ENa electromotive force of the Na+ transport mechanism 1 925680 ENa equilibrium potential for Na+ 1 925686 ENa excretion of urinary Na+ 1 925685 ENa experimental determinations and meanings of the overall electromotive force 1