Exocytosis in Pheochromocytoma Cells after Exposure to a High Concentration of Potassium

Abstract

An electron-microscopic study revealed exocytosis of electron-dense granules in rat pheochromocytoma (PC12) cells after 1-min exposure to a high concentration of potassium medium. Numerous omega profiles indicative of the exocytosis were seen in the surface membrane of the PC12 cells. Most omega profiles showed clear or did not contain the granule contents. Sometimes, the granular, flocculent or dense materials were seen within the omega profiles that were exposed directly to the extracellular medium. Moreover, noncoated or coated omega profiles were observed. Coated vesicles were also visible under the surface membrane. The present study suggests that PC12 cells retain the exocytotic release mechanism for catecholamines.

Compensatory endocytosis in chromaffin cells

“…2004). Classic ultrastructure studies of stimulated endocrine cells provided snapshots of both omega shaped membrane invaginations where the vesicle lumen has aqueous access to the outside through a narrow pore (Heuser & Reese 1973, Patzak & Winkler 1986, Oomori et al. 1991).…”

Exocytosis in the antral gastrin cells of mouse, rat, and guinea pig after stimulation by carbamylcholine

“…If the process is faster in other species, it would thus be difficult to capture by the same methods (Brooks and Carmichael 1987). In experiments in vitro, exocytotic figures in other mammals have been demonstrated by conventional electron microscopy in bovine adrenal chromaffin cells (Patzak and Winkler 1986) and in rat pheochromocytoma cells (Oomori et al 1991). Exocytotic figures have been captured successfully in various neurons and in endocrine and neuroendocrine cells by using tannic-acidcontaining fixatives (Endo and Nishitsutsuji-Uwo 1982;Buma et al 1984;Brooks and Carmichael 1987;Carmichael et al 1989;Roubos et al 1990;Golding and Pow 1990;Morris and Pow 1991;Pow and Morris 1991).…”