Human adipose cells have voltage-dependent potassium currents

The whole-cell patch-clamp method was used to study the membrane electrical properties of human adipocyte cells obtained by differentiating from precursors of human abdominal and mammary tissues. All differentiated cells exhibited outward currents with sigmoidal activation kinetics. The outward currents showed activation thresholds between -20 to -30 mV and slow inactivation. The ionic channels underlying the macroscopic current were highly selective for K+. Their selectivity was for typical K+ channels with relative permeabilities of K+ > NH4+ > Cs+ > Na+. No evidence of any other type of voltage-gated channel was found. The potassium currents (I-Kv) were blocked reversibly by tetraethylammonium and barium. The IC50 value and Hill coefficient of tetraethylammonium inhibition of I-Kv were 0.56 mm and 1.17 respectively. These results demonstrate that human adipose cells have voltage-dependent potassium currents.