Inhibition of active transport causes potassium leakage accompanied by the uptake of a nearly equivalent amount of Na. A number of agents, such as fluoride, iadoacetate -~ adenosine, and lead (c. f. PAssow 1963) not only inhibit the uphill movements of K and Na but enhance the downhill movements of K ten-to thirtyfold without appreciably increasing the passive Na influx. Triose reductone [I-IC(OH) = C(OI-I) --CKO] and its hydrazine derivative were found to exert similar actions. In the present paper information is provided on the behavior of triose reductone in saline solutions, its reactions with hydrazine, and the conditions under which it produces its specific effect on potassium permeability of human erythrocytes.
Triose reductone is readily oxidized by atmospheric oxygen at high pit values, but is fairly stable in the acid range. It reacts spontaneously with hydrazine, although the reaction rate is low. Enzymes present in the interior of the erythroeyte enhance this reaction. The product contains 2 moles of hydrazine per mole of reductone. Neither reductone nor its hydrazine derivative seem to form chelates with alkaline earth metal ions. Both exert little effect on red cell metabolism as judged from the fact that they induce but little ATP breakdown. They are metabolically converted into unidentified end products. This process is not affected by the presence of ethylenediaminetetraacetic acid (EDTA).
The action on cation permeability of triose reductone and of its hydrazine derivative depends on the metabolic state of the cells. In the concentration range studied (0.5--10.0 mmoles/t) fresh erythrocytes are scarcely affected whereas cells incubated in the absence of substrates prior to the addition of the poison lose potassium with little concomitant sodium uptake. The hydrazine derivative is much more effective than reductone itself. In cells preincubated for 16 hours it may cause, within 2 hours, a net loss of about 60 mequiv K/kg cells with Na uptake of as little as 5 mequiv/kg cells. Potassium loss can be induced only in the presence of Ca. At 0.5 mmoles/1 CaC12 a maximum effect is reached whereas an excess of EDTA prevents the permeability change to occur.
Beim aktiven Kationentransport sind Kalium-und Natriumbewegungen miteinander gekoppelt. Jede Hemmung der Ionenpumpe ffihrt daher gleichzeitig zu Kaliumverlust and Natriumaufnahme. Diese Ionenverschiebungen ver]aufen bei den Erythrocyten nur langsam -sic betragen etwa 1--2,5 mJkquiv./kg Zellen/Std --und mit anni~hernd gleicher Gesehwindigkeit, so dal~ sich die Summe der intracel]uli~ren K-und Na-Ionen sowie das Zellvolumen nur wenig i~ndert. Eine t~eihe Pfliigers Arch. ges. Physiol., Bd. 288 1