Ca^sup 2+^-sensitive and Ca^sup 2+^-insensitive exocytosis in maize coleoptile protoplasts

Ca2+ and osmotic driven extension of the surface area of maize coleoptile protoplasts was investigated using capacitance measurements and photolysis of the caged compound DM-nitrophen. Protoplasts responded to an elevation of cytoplasmic Ca2+ (Cai) with a rapid burst in capacitance reaching a maxima...

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Bibliographic Details
Published in:Pflügers Archiv 2000-07, Vol.439 (7), p.R152
Main Authors: Thiel, Gerhard, Sutter, Jens-uwe, Homann, Ulrike
Format: Article
Language:English
Online Access:Get full text
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Summary:Ca2+ and osmotic driven extension of the surface area of maize coleoptile protoplasts was investigated using capacitance measurements and photolysis of the caged compound DM-nitrophen. Protoplasts responded to an elevation of cytoplasmic Ca2+ (Cai) with a rapid burst in capacitance reaching a maximal increase of 1.3 ±1.1 % over the resting cell capacitance. Subsequent lowering of the osmotic potential in the external medium by 210 mosmol caused a further increase in Cm by 26±6 %. These data indicate two independent pathways for insertion of membrane into the plasma membrane. One is driven by Cai and recruits membrane from a small pool. The osmotic evoked rise in surface area draws membrane from a much larger reservoir and may be driven by membrane tension.
ISSN:0031-6768
1432-2013
DOI:10.1007/BF03376555