Sodium Pump in T-Tubules of Frog Muscle Fibers

Abstract

It is well known that in the cytosol of most cells the high concentration of K+ ([K +] i ) and the relatively low concentration of Na+ ([Na+] i ) are kept constant in spite of their electrochemical gradients, which promotes the loss of K+ and the gain of Na+. The steadiness of [K +], and [Na+] i , is maintained by a metabolic energy-dependent active transport process first proposed by Dean(1) in skeletal muscle and known as the Na+ pump (Dean coined the name) or more properly as the Na + /K + pump.