Effect of external K+ concentration on transmembrane potentials of rabbit thyroid cells

Abstract

The effect of extracellular K+ concentration on the transmembrane potential of the perfused rabbit thyroid was studied. The normal thyroid membrane potential was found to be -43 mv. The membrane potential varied with [K+]q about in the same manner as found in other tissues, and the data are well approximated by the Goldman equation. However, the extrapolated intracellular [K+] is only about 85 m[image], a value substantially lower than measured [K+]i'' s. The ratio, PK/PNa is estimated to be about 0.1.