Activation of Na+ and K+ pumping modes of (Na,K)-ATPase by an oscillating electric field

• Published in: The Journal of biological chemistry Vol. 265; no. 13; pp. 7260 - 7267
• Main Authors: Liu, D S, Astumian, R D, Tsong, T Y
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Biochemistry and Molecular Biology 05.05.1990
• Subjects: Adenosine Triphosphate - blood; Analytical, structural and metabolic biochemistry; Biological and medical sciences; Biological Transport, Active; Electric Stimulation - methods; Enzymes and enzyme inhibitors; Erythrocytes - enzymology; Erythrocytes - metabolism; Fundamental and applied biological sciences. Psychology; Humans; Hydrolases; Kinetics; Mathematics; Models, Theoretical; Ouabain - pharmacology; Potassium - blood; Rubidium - blood; Sodium - blood; Sodium-Potassium-Exchanging ATPase - blood; Spectrometry, Fluorescence; Electric field; Membrane pump; Sodium; Enzyme; Na,K-ATPase; Ion transport; Activation; Potassium; Computer aid; Fluorescence spectrometry
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/s0021-9258(19)39108-2

Serpersu and Tsong (Sepersu, E. H., and Tsong, T. Y. (1983) J. Membr. Biol. 74, 191-201; (1984) J. Biol. Chem. 259, 7155-7162) reported activation of a K+ pumping mode of (Na,K)-ATPase by an oscillating electric field (20 V/cm, 1.0 kHz). Their attempts to activate Na+ pumping at the same frequency were unsuccessful. We report here activation of a Na+ pumping mode with an oscillating electric field of the same strength as used previously (20 V/cm) but at a much higher frequency (1.0 MHz). At 3.5 degrees C and the optimal amplitude and frequency, the field-induced, ouabain-sensitive (0.2 mM ouabain incubated for 30 min) Rb+ influx ranged between 10 and 20 amol/red blood cell/h, and the corresponding Na+ efflux ranged between 15 and 30 amol/red blood cell/h, varying with the source of the erythrocytes. No Rb+ efflux nor Na+ influx was stimulated by the applied field in the frequency range 1 Hz to 10 MHz. These results indicate that only those transport modes that require ATP splitting under the physiological condition were affected by the applied electric fields, although the field-stimulated Rb+ influx and Na+ efflux did not depend on the cellular ATP concentration in the range 5 to 800 microM. Computer simulation of a four-state enzyme electroconformationally coupled to an alternating electric field (Tsong, T. Y., and Astumian, R. D. (1986) Bioelectrochem. Bioenerg. 15, 457-476; Tsong, T. Y. (1990) Annu. Rev. Biophys. Biophys. Chem. 19, 83-106) reproduced the main features of the above results.