Active cation pumping of Na+,K+-ATPase and sarcoplasmic reticulum Ca2+-ATPase induced by an electric field.
To explain these results, we have proposed that the applied electric field induces a shift in the enzyme conformational equilibria through coulombic interaction. When the electric field is removed, or when it reverses its sign, the system returns to its initial state, and in the process of returning the free energy absorbed from the electric field is released. This released energy is used to drive active transport of an ion or to synthesize ATP. Models based on the concept of the "electroconformational coupling" have been analyzed and shown to work as predicted. Most cells maintain a steady-state transmembrane potential. This is an energy-consuming process, and as such, it must serve certain functions or purposes. Experiments discussed here would suggest that activation or regulation of ion-transport system is one of these function. Other experiments have shown that electric fields can stimulate ATP synthesis, cell proliferation, membrane fusion, DNA and RNA biosynthesis, etc. (for review see, e.g., Refs. 5 and 12). Apparently, the activation of ATPases is the most fundamental because this class of enzymes can transduce energy from on form to another, including transduction of electric energy to chemical bond energy of ATP and chemical potential energy of cations.
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D000818:Animals; D001693:Biological Transport, Active; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D004558:Electric Stimulation; D004594:Electrophysiology / Q000295:instrumentation / Q000379:methods; D004912:Erythrocytes / Q000201:enzymology; D006801:Humans; D012413:Rubidium / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D000252:Calcium-Transporting ATPases; D000254:Sodium-Potassium-Exchanging ATPase; D012413:Rubidium