Some effects of trinitrocresolate and valinomycin on Na and K transport across thin lipid bilayer membranes: A steady-state analysis with simultaneous tracer and electrical measurements

Autor: Ginsburg, H., Tosteson, M. T., Tosteson, D. C.
Zdroj: Journal of Membrane Biology; June 1978, Vol. 42 Issue: 2 p153-168, 16p
Abstrakt: Summary This paper describes the effect of trinitrocresolate anions (TNC-) on the electrical conductance (Gm), and tracer-measured unidirectional Na and K fluxes (MNa andMK) across bilayers formed from sheep red cell lipids dissolved in decane. In the absence of TNC-, typical low conductances were observed, while the cation fluxes were too low to measure by our techniques (<10-12 moles cm-2 sec-1). In the presence of TNC- (10-2m),Gm increased and TNC- was the main charge carrier in the system. The cationic fluxes were also much increased, but the membranes showed no significant selectivity between K and Na. Furthermore, the Na and K fluxes were at least two orders of magnitude larger than the ionic fluxes calculated fromGm. Thus, almost all of the K and Na transport across the membrane in the presence of TNC- is electrically silent and is probably carried out as KTNC and NaTNC ion pairs.
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