EFFECTS OF NORADRENALINE AND INSULIN ON ELECTRICAL-ACTIVITY IN WHITE ADIPOSE-TISSUE OF RAT

An active change in membrane voltage responses to hyperpolarizing puls es has been identified by intracellular recording on an in vitro prepa ration of white adipose tissue. This change was characterized by a slo w return to baseline at the offset of the pulses. Amplitude and durati on of the slow return to baseline were dependent on extracellular K+ c oncentration, and were diminished by external application of Ba2+. Suc h properties suggest that this electrical response can be mainly due t o activation of transient K+ conductances. The effects that noradrenal ine and insulin have over the slow return to baseline have been also s tudied. While external addition of noradrenaline decreased amplitude a nd duration of this electrical response, insulin produced the opposite effect. These results suggest that noradrenaline and insulin could mo dulate K+ conductances in white adipocytes.