Abstract
We studied the Na+/K+ pump in red cells from an obese human subject (MAJ) in which the number of pumps/cell was 10-20 times higher than normal. Through measurements of the kinetic properties of several modes of operation of the Na+/K+ pump we determined that the pumps in MAJ cells are kinetically normal. In the presence of adequate metabolic substrate the maximum rates of Na+ pumping and lactate production saturated at 60 and 12 nmol/1 cell per h, respectively. Under physiological conditions pump and "leak" Na+ fluxes were similar in MAJ and normal cells. Since internal Na+ was lower in MAJ than in normal cells (Nai+ approximately 2 and 8 mmol/1 cell, respectively), we conclude that the reduction in cell Na+ allows the Na+/K+ pump in MAJ cells to operate at lower fraction of maximum capacity and to compensate for the increased number of pumps.
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- BERNSTEIN R. E. Alterations in metabolic energetics and cation transport during aging of red cells. J Clin Invest. 1959 Sep;38:1572–1586. doi: 10.1172/JCI103936. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Baginski E. S., Foá P. P., Zak B. Determination of phosphate and phosphomonoesterases in biologic materials. Am J Med Technol. 1969 Aug;35(8):475–486. [PubMed] [Google Scholar]
- Brugnara C., Kopin A. S., Bunn H. F., Tosteson D. C. Regulation of cation content and cell volume in hemoglobin erythrocytes from patients with homozygous hemoglobin C disease. J Clin Invest. 1985 May;75(5):1608–1617. doi: 10.1172/JCI111867. [DOI] [PMC free article] [PubMed] [Google Scholar]
- DeLuise M., Flier J. S. Functionally abnormal Na+-K+ pump in erythrocytes of a morbidly obese patient. J Clin Invest. 1982 Jan;69(1):38–44. doi: 10.1172/JCI110439. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Funder J. Alkali metal cation transport through the human erythrocyte membrane by the anion exchange mechanism. Acta Physiol Scand. 1980 Jan;108(1):31–37. doi: 10.1111/j.1748-1716.1980.tb06497.x. [DOI] [PubMed] [Google Scholar]
- Garay R. P., Garrahan P. J. The interaction of sodium and potassium with the sodium pump in red cells. J Physiol. 1973 Jun;231(2):297–325. doi: 10.1113/jphysiol.1973.sp010234. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Garrahan P. J., Glynn I. M. Facftors affecting the relative magnitudes of the sodium:potassium and sodium:sodium exchanges catalysed by the sodium pump. J Physiol. 1967 Sep;192(1):189–216. doi: 10.1113/jphysiol.1967.sp008296. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Garrahan P. J., Glynn I. M. The behaviour of the sodium pump in red cells in the absence of external potassium. J Physiol. 1967 Sep;192(1):159–174. doi: 10.1113/jphysiol.1967.sp008294. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Garrahan P. J., Glynn I. M. The incorporation of inorganic phosphate into adenosine triphosphate by reversal of the sodium pump. J Physiol. 1967 Sep;192(1):237–256. doi: 10.1113/jphysiol.1967.sp008298. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Glynn I. M., Hoffman J. F. Nucleotide requirements for sodium-sodium exchange catalysed by the sodium pump in human red cells. J Physiol. 1971 Oct;218(1):239–256. doi: 10.1113/jphysiol.1971.sp009612. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Glynn I. M., Lew V. L., Lüthi U. Reversal of the potassium entry mechanism in red cells, with and without reversal of the entire pump cycle. J Physiol. 1970 Apr;207(2):371–391. doi: 10.1113/jphysiol.1970.sp009067. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Glynn I. M., Lew V. L. Synthesis of adenosine triphosphate at the expense of downhill cation movements in intact human red cells. J Physiol. 1970 Apr;207(2):393–402. doi: 10.1113/jphysiol.1970.sp009068. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Halperín J., Schaeffer R., Galvez L., Malavé S. Ouabain-like activity in human cerebrospinal fluid. Proc Natl Acad Sci U S A. 1983 Oct;80(19):6101–6104. doi: 10.1073/pnas.80.19.6101. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Joiner C. H., Lauf P. K. Modulation of ouabain binding and potassium pump fluxes by cellular sodium and potassium in human and sheep erythrocytes. J Physiol. 1978 Oct;283:177–196. doi: 10.1113/jphysiol.1978.sp012495. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kaplan J. H. Sodium ions and the sodium pump: transport and enzymatic activity. Am J Physiol. 1983 Sep;245(3):G327–G333. doi: 10.1152/ajpgi.1983.245.3.G327. [DOI] [PubMed] [Google Scholar]
- Kelly R. A., O'Hara D. S., Canessa M. L., Mitch W. E., Smith T. W. Characterization of digitalis-like factors in human plasma. Interactions with NaK-ATPase and cross-reactivity with cardiac glycoside-specific antibodies. J Biol Chem. 1985 Sep 25;260(21):11396–11405. [PubMed] [Google Scholar]
- Lew V. L., Hardy M. A., Jr, Ellory J. C. The uncoupled extrusion of Na+ through the Na+ pump. Biochim Biophys Acta. 1973 Oct 11;323(2):251–266. doi: 10.1016/0005-2736(73)90149-1. [DOI] [PubMed] [Google Scholar]
- Pollack L. R., Tate E. H., Cook J. S. Na+, K+-ATPase in HeLa cells after prolonged growth in low K+ or ouabain. J Cell Physiol. 1981 Jan;106(1):85–97. doi: 10.1002/jcp.1041060110. [DOI] [PubMed] [Google Scholar]
- Sachs J. R. Sodium movements in the human red blood cell. J Gen Physiol. 1970 Sep;56(3):322–341. doi: 10.1085/jgp.56.3.322. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sachs J. R., Welt L. G. The concentration dependence of active potassium transport in the human red blood cell. J Clin Invest. 1967 Jan;46(1):65–76. doi: 10.1172/JCI105512. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Simons T. J. Potassium: potassium exchange catalysed by the sodium pump in human red cells. J Physiol. 1974 Feb;237(1):123–155. doi: 10.1113/jphysiol.1974.sp010474. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sugerman H. J., Pollock T. W., Rosato E. F., Delivoria-Papadopoulos M., Miller L. D., Oski F. A. Experimentally induced alterations in affinity of hemoglobin for oxygen. II. In vivo effect of inosine, pyruvate, and phosphate on oxygen-hemoglobin affinity in rhesus monkey. Blood. 1972 Apr;39(4):525–529. [PubMed] [Google Scholar]
- Tosteson D. C. Cation countertransport and cotransport in human red cells. Fed Proc. 1981 Apr;40(5):1429–1433. [PubMed] [Google Scholar]
- Wieth J. O. Paradoxical temperature dependence of sodium and potassium fluxes in human red cells. J Physiol. 1970 May;207(3):563–580. doi: 10.1113/jphysiol.1970.sp009081. [DOI] [PMC free article] [PubMed] [Google Scholar]