THE EFFECT OF LOCAL ANESTHETIC AND pH ON SODIUM AND POTASSIUM FLUX IN HUMAN RED CELLS?

¹ Department of Anesthesiology, College of Medicine, University of Florida, Gainesville, Florida

The effect of a series of local anesthetics on sodium and potassium in- and outfiux was studied in human red cells at pH 6.0 ( 1.5% of the anesthetic present as the free base) and pH 8.0 ( 10% present as the base) . In cells reincubated after cold storage, labeled sodium was present outside or labeled potassium inside the cells. Rate constants for sodium influx or potassium outfiux were derived from changes in intracellular specific activity. Intracellular cation changes were measured, and the in- and outfiuxes were estimated and listed in miuiequivalents per liter per time. In steady- state fresh cells the influx of labeled sodium or potassium was determined. At pH 6.0 the local anesthetics in concentrations used for clinical anesthesia inhibited sodium influx and outfiux. A lidocaine analog without anesthetic activity did not have this effect. The cation may have been the active structure of local anesthetics. Both potassium in- and outfiuxes were inhibited at pH 6.0 by local anesthetic concentrations smaller than those affecting the sodium fluxes. At pH 8.0 the local anesthetics increased membrane permea bility to sodium influx and potassium outfiux, while a dual effect was noted on sodium outflu. x and potassium influx.