Na+

Na+

sodium ion.

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Na+ gradient

the rate of increase or decrease of sodium ion concentration.

Na+ pump

see sodium pump.

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Na+,K+-ATPase

widely distributed enzyme consisting of two large a-subunits and two smaller ß-subunits, whose function is to transport Na+ and K+ against their concentration gradients using hydrolysis of ATP as the thermodynamic couple. The stoichiometry of exchange is two K+ for every three Na+ pumped. Often called the sodium pump.