EXOCYTOTIC MEMBRANE-FUSION AS STUDIED IN TOXIN-PERMEABILIZED CELLS

This chapter discusses the exocytotic membrane fusion as studied in toxin- permeabilized cells. Permeabilized cells have been widely used in the analysis of exocytotic membrane fusion or intracellular Ca 2+ regulation. They allow the study of the function of intracellular organelles in situ under conditions that are close to the physiological situation in intact cells. Toxin-permeabilized preparations have also been instrumental in analyzing the intracellular glucose metabolism in hepatocytes, the chain of events leading to smooth muscle contraction, and the regulation of intracellular Ca 2+ sequestration. In most of the studies dealing with exocytosis from permeabilized cells, an “intracellular medium” containing potassium as a main cation and glutamate as an anion I was used. Because the free Ca 2+ concentration within the cells under resting conditions, as well as during stimulation, is in the micromolar range, this ion must be carefully controlled in the buffers used. © 1993, Elsevier Inc. All rights reserved.