THE EFFECT OF TRIS(HYDROXYMETHYL) AMINOMETHANE ON THE POTASSIUM CONTENT AND THE MEMBRANE POTENTIAL OF LIVER CELLS

¹ Laboratory of Experimental Surgery, University of Louvain, Belgium

The effect of tris(hydroxymethyl) aminomethane (THAM) on the movements of potassium in the liver was studied in nine dogs by means of catheterization of the hepatic vessels, and in the course of 38 perfusions of isolated dog livers. In both cases the injection of THAM led to a liberation of hepatic potassium. The potassium depletion that was produced by THAM at pH 10.2 or 7.2 did not depend on the variations of extracellular pH. This effect persisted when active ion transport had been blocked by ouabain and was associated with a marked but transient increase in the membrane potential. It is concluded that THAM, which (as was demonstrated with ¹⁴C-labeled THAM) penetrates rapidly into the liver cells, increases the membrane permeability to potassium ions in those cells where the measured membrane potential is lower than the equilibrium potential for potassium. It is suggested that this change may be followed by an increased permeability to sodium ions which would reduce the membrane potential to its initial value.