Properties of Ca2+-dependent K+ Channels of Human Gingival Fibroblasts

Abstract

Cells in the oral cavity are normally exposed to different temperatures. Ion transport systems are influenced by temperature in other tissues: In particular, changes in intracellular K+ ion can affect cell growth and synthesis of macromolecules. The purpose of this investigation was to identify K+ channels in human gingival fibroblast cells and analyze the effect of temperature on their K+ conduction properties. Ca2+-dependent K+ channels with a large conductance (125 pS in symmetrical K+-rich solutions) were identified in human gingival fibroblasts and studied by the patch-clamp technique. The open probability of the channels varied with membrane potential between +40 and -100 mV. When the bath temperature was decreased from 40 to 4°C, channel conductance was reduced, but the mean open time of the channels was increased. The activation energies for the conductance and the reciprocal of the mean open time were estimated to be 9.1 and 22.9 kj/mol, respectively. These values are lower than those reported for these and other types of channels in cells from other tissues. The open probability of the channels was nearly constant in the temperature range studied. These results suggest that the properties of Ca2+-dependent K+ channels of gingival fibroblasts remain relatively unchanged when the cells are exposed to a wide range of temperatures.