Bicarbonate-Chloride Exchange in Erythrocyte Suspensions

摘要: A pH-sensitive glass electrode was used in a temperature-controlled stopped-flow rapid reaction apparatus to determine rates of pH equilibration red cell suspensions. The requires less than 2 ml reactants. is insensitive pressure and flow variations, has response time 3 extracellular carbonic anhydrase mixed with an equal volume 30 mM phosphate buffer at 6.7. Within few milliseconds after mixing, HCO - reacts H + form CO , which enters the cells rehydrates producing electrochemical potential gradient for from inside outside cells. then leaves exchange Cl increases as flowing out . Flux calculated dpH/d t during -Cl exchange, velocity constant computed flux intracellular [HCO ]. activation energy process 18.6 kcal/mol between 5°C 17°C (transition temperature), 11.4 40°C. energies transition temperature are not significantly altered presence potent anion inhibitor (SITS), although fluxes markedly decreased. These findings suggest that rate-limiting step changes 17°C, either because alteration nature transport site or physical state membrane lipids affecting protein-lipid interactions.