Effects of noradrenaline and insulin on electrical activity in white adipose tissue of rat.

An active change in membrane voltage responses to hyperpolarizing pulses has been identified by intracellular recording on an in vitro preparation of white adipose tissue. This change was characterized by a slow return to baseline at the offset of the pulses. Amplitude and duration of the slow return to baseline were dependent on extracellular K+ concentration, and were diminished by external application of Ba2+. Such properties suggest that this electrical response can be mainly due to activation of transient K+ conductances. The effects that noradrenaline and insulin have over the slow return to baseline have been also studied. While external addition of noradrenaline decreased amplitude and duration of this electrical response, insulin produced the opposite effect. These results suggest that noradrenaline and insulin could modulate K+ conductances in white adipocytes.