Author/Editor		Chowdhury, HH; Grilc, S; Zorec, R
Title		Insulin induces a rapid increase in membrane area in single rat adipocytes
Type		članek
Source		Adipocytes
Vol. and No.		Letnik 1, št. 2
Publication year		2005
Volume		str. 131-8
Language		eng
Abstract		Adipocytes vary greatly in their size and large adipocytes are associated with diseased states such as the metabolic syndrome and type 2 diabetes. However, the mechanism of adipocyte growth is not entirely clear. To study this process, we monitored exocytosis and endocytosis, which contribute to membrane surface area fluctuations, and therefore influence cell size. Here we measured single cell membrane area directly by patchclamp measurements of membrane capacitance (Cm), a parameter related to membrane area. In particular, we studied whether insulin affects membrane area dynamics in single adipocytes, since increased insulin concentration is associated with a number of physiological and pathological conditions. Experimental evidence shows that a 5-minute exposure of cells to insulin increases resting Cm by 12 +- 4 %. In controls, the change in Cm was 2 +- 2 %, not different from zero. By using confocal microscopy to measure membrane FM1-43 fluorescence intensity to monitor cumulative exocytosis, we show that the insulin-induced increase in Cm is due to stimulated exocytosis.
Descriptors		ADIPOCYTES INSULIN ADIPOSE TISSUE EXOCYTOSIS ENDOCYTOSIS CELL SIZE ELECTRIC CONDUCTIVITY PATCH-CLAMP TECHNIQUES MICROSCOPY, CONFOCAL FLUOROMETRY RATS, WISTAR