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1.  Cation Effects on Chloride Fluxes and Accumulation Levels in Barley Roots 
The Journal of General Physiology  1966;50(1):225-241.
Accumulation of Cl- by excised barley roots, as of K+, approaches a maximum level at which the ion influx and efflux rates become equal. The rate of Cl- influx at this equilibrium is close to the initial rate while the efflux rate increases with time from zero to equality with influx. The Cl- fluxes are independent of simultaneous exchange flux of the cations, but depend on the nature and concentration of the salt solutions from which they originate. The Cl- content at equilibrium, however, is largely independent of the external concentrations. The approach to equilibrium reflects the presence of the cation. Cl- flux equilibrium is attained more rapidly in KCl than in CsCl or CaCl2. This is presumably an effect of much slower distribution of Cs+ and Ca++ than of K+ within the roots. Accumulated Cs+ appears to form a barrier to ion movement primarily within the outermost cells, thereby reducing influx and ultimately efflux rates of both Cl- and cations. Slow internal mixing and considerable self-exchange of the incoming ions suggest internal transport over a series of steps which can become rate-limiting to the accumulation of ions in roots.
PMCID: PMC2225633  PMID: 5971030
2.  Equilibrium and Ion Exchange Characteristics of Potassium and Sodium Accumulation by Barley Roots 
The Journal of General Physiology  1965;48(4):601-616.
Potassium ion and Na+ influx and efflux rates into and from excised barley roots are compared with the maximum capacity of accumulation. Potassium ion and Na+ influx and efflux involve a cation exchange that is independent of simultaneous exchange of the accompanying anion. These exchange fluxes depend on the concentration and cation composition of the solutions from which they originate. Selective differences between K+ and Na+ fluxes are sufficient to account for a cationic distribution within the roots that differs markedly from that of the external solution and that persists for extended time periods. The accumulation maximum is a cation exchange equilibrium with the cation influx and efflux rates approaching equality. The equilibrium level is independent of the individual cation fluxes and the external solution concentration. It is a finite quantity which appears to be determined by the internal anion concentration including accumulated as well as endogenous anions.
PMCID: PMC2195438  PMID: 19873558
3.  Cation-Anion Balance during Potassium and Sodium Absorption by Barley Roots 
The Journal of General Physiology  1963;46(3):369-386.
Steady-state rates of potassium ion and sodium ion absorption by excised barley roots accompanied by various anions were compared with the rates of anion absorption and the concomitant H+ and base release by the roots. The cation absorption rates were found to be independent of the identities, concentrations, and rates of absorption of the anions of the external solution, including bicarbonate. Absorption of the anion of the salt plus bicarbonate could not account for the cation absorption. H+ is released during cation absorption and base during anion absorption. The magnitude by which one or the other predominates depends on the relative rates of anion and cation absorption under various conditions of pH, cation and anion concentration, and inhibitor concentrations. The conclusion is that potassium and sodium ions are absorbed independently of the anions of the absorption solution in exchange for H+, while anions are exchanged for a base. The H+ release reflects a specificity between K+ and Na+ absorption such that it appears to be H+ exchanged in the specific rate-limiting reactions of the cation absorption.
PMCID: PMC2195277  PMID: 13964256

Results 1-3 (3)