A comparison of the effects of ouabain and 2-deoxy-d-glucose on the thermodynamic variables of the frog skin |
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Authors: | Albert Owen S Roy Caplan Alvin Essig |
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Institution: | 1. Biophysical Laboratory, Harvard Medical School, Cambridge, Mass. U.S.A.;2. Laboratory of Membranes and Bioregulation, Weizmann Institute of Science, Rehovot Israel;3. The Department of Physiology, Boston University School of Medicine, Boston, Mass. U.S.A. |
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Abstract: | Previous studies support the validity of a linear thermodynamic formalism relating the rates of active Na+ transport and oxygen consumption Jr to the electrical potential difference ΔΨ an the affinity α (negative free energy) of the metabolic driving reaction. The formulation was further tested in paired control and experimental hemiskins by the use of two inhibitors of Na+ transport. Ouabain, a specific inhibitor of the Na+ pump, might be expected to diminish the dependence of Jr on ΔΨ without affecting α, whereas 2-deoxy-d-glucose, a competitive inhibitor of glucose metabolism, should be expected to diminish α. Both inhibitors were used at concentrations adequate to depress Na+ transport (i.e. short-circuit current Jo) to some 50°o of control level. Measurements were made of Io and , and the apparent value of the affinity αapp was calculated according to the thermodynamic formulation. Ouabain depressed without affecting αapp whereas 2-deoxy-d-glucose depressed αapp without affecting . The demonstration of these effects indicates the utility of the formalism. |
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