Electrophysiological and electron microprobe studies of ion transport in cold acclimated brown adipocyte.

点击翻译按钮获取中文摘要

Brown adipose tissue cell has much quantity of Lipid droplets and motochondria which contain heat productive protein, thermogenin (uncoupling protein) and electron transfer system in the inner membrane. These are involved in the process of heat production during cold acclimation in animals.The transport of ions in warm (WA) and cold (CA) acclimated rat brown adipocytes and the patch clamp method of reconstituted purified mitochondria of adipocytes were investigated.The electrophysiological recordings of Xenopus oocytes injected with total RNA extracted from CA and WA were also performed.Morphometric analyses of brown adipocytes showed that lipid droplets occupied 75% of the WA cells and 37% of the CA cells. The area of a single mitochondrion in CA cells was three times that of one in the WA cells. X-ray microanalysis showed that Na was higber, and K and Cl were lower in CA than WA, in both the nucleus and the mitochondria. Moreover, Ca (total) was higher in the mitochondria, whereas was lower in the nucleus of CA cells than in WA cells. Confocal laser scanning microscopy was performed also. Acridine orange (AO), a fluorescent dye which can indicate a H^+ gradient, was localized exclusively in the mitochondria rich cytoplasm of CA cells. The fluorescence intensity of fluo-3 (Ca^<2+>indicating dye), which was loaded for 30 ruin, increased within 1 min of noradrenaline (NA) exposure in the cytoplasm of WA and CA cells. In contrast, in the nucleus with NA application fluorescence intensity rose after an initial decrease in WA, and in CA decreased gradually. The patch clamp record shows achannel activity when the reconstituted mitochondrial membrane has some voltage and pH gradient. The whole cell clamp record from Oocyte injected with total RNA of CA shows the voltage dependent outward currents.