A comparison of the effects of ouabain and 2-deoxy-D-glucose on the thermodynamic variables of the frog skin.
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 delta-psi and the affinity A (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 delta-psi without affecting A, whereas 2-deoxy-D-glucose, a competitive inhibitor of glucose metabolism should be expected to diminish A. Both inhibitors were used at concentrations adequate to depress Na-+ transport (i.e. short-circuit current Io) to some 50% of control level. Measurements were made of Io and dJr/d(delat-psi), and the apparent value of the affinity Aapp was calculated according to the thermodynamic formulation. Ouabain depressed minus dJr/d(delta-psi) without affecting Aapp whereas 2-deoxy-D-glucose depressed Aapp without affecting minus dJr/d(delta-psi). The demonstration of these effects indicated the utility of the formalism.
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D003837:Deoxy Sugars / Q000494:pharmacology*; D003847:Deoxyglucose / Q000494:pharmacology*; D066298:In Vitro Techniques; D008722:Methods; D008954:Models, Biological; D010042:Ouabain / Q000008:administration & dosage / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000187:drug effects; D011894:Rana pipiens; D012867:Skin / Q000378:metabolism; D012879:Skin Physiological Phenomena; D012964:Sodium / Q000378:metabolism; D013816:Thermodynamics
D003837:Deoxy Sugars; D010042:Ouabain; D003847:Deoxyglucose; D012964:Sodium