Rubidium-86 uptake and energy metabolism in suspended human erythrocytes monitored by microdialysis.
We aimed to develop a model for studying membrane leakiness. A microdialysis technique was used to investigate rubidium-86 (86Rb) uptake in suspended human erythrocytes in vitro, with the aim of later applying the technique to in vivo studies. Suspensions were prepared from washed erythrocytes and 86Rb administered directly or via the microdialysis probe. The effects on 86Rb uptake of varying the haematocrit were measured. Erythrocytes were also treated with the K+ ionophore valinomycin or the Na+/K+-ATPase inhibitor ouabain. The effects on 86Rb uptake, microdialysate content of lactate and pyruvate, and erythrocyte content of 2,3-bisphosphoglycerate (2,3-BPG) were measured. Valinomycin dissipates the potassium gradient and activates Na+/K+-ATPase, demonstrated by decreased erythrocyte 86Rb uptake with increasing concentrations of valinomycin. This increased ion pump activity enhanced glycolysis, which was demonstrated by accumulation of pyruvate and lactate due to enhanced consumption of 2,3-BPG. The microdialysis technique is appropriate for in vitro studies of ion fluxes across cellular membranes.
Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden. johan.ljungberg@vll.se
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Ljungberg
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Waldenström
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Ronquist
D019794:2,3-Diphosphoglycerate / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D006019:Glycolysis; D006400:Hematocrit; D006801:Humans; D007476:Ionophores / Q000494:pharmacology; D017551:Microdialysis; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000737:chemistry; D012414:Rubidium Radioisotopes / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D013997:Time Factors; D014634:Valinomycin / Q000494:pharmacology
D004791:Enzyme Inhibitors; D007476:Ionophores; D012414:Rubidium Radioisotopes; D019794:2,3-Diphosphoglycerate; D014634:Valinomycin; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium