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Activation of exocytosis by GTP analogues in adrenal chromaffin cells revealed by patch‐clamp capacitance measurement
Author(s) -
Burgoyne Robert D.,
Handel Susan E.
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)00361-0
Subject(s) - exocytosis , chromaffin cell , patch clamp , gtp' , clamp , capacitance , chemistry , biophysics , microbiology and biotechnology , endocrinology , adrenal medulla , biology , catecholamine , biochemistry , secretion , computer science , receptor , electrode , enzyme , clamping , computer vision
The role of GTP‐binding proteins in exocytosis in bovine adrenal chromaffin cells was examined using patch‐clamp capacitance measurement. Internal dialysis with the non‐hydrolysable GTP analogue guanosine 5′‐[βγ‐imido]triphosphate and xanthosine triphosphate (XTP) activated a capacitance increase. Exocytosis triggered by XTP was blocked by guanosine 5′‐[β‐thio]diphosphate (GDPβS) but Ca 2+ ‐induced exocytosis was unaffected. The capacitance increase due to XTP could not be explained by Ca 2+ mobilisation since Ins(1,4,5)P 3 and caffeine did not mimic the response. Chromaffin cells appear to possess a Ca 2+ ‐independent pathway for exocytosis that involves GTP‐binding proteins. The magnitude of the response to XTP suggested that GTP analogues stimulate both exocytosis and recruitment of secretory granules.