The peritrich ciliate Vorticella sp. exhibits cellular contraction of an all-or-nothing type in response to a mechanical stimulus. Many authors have suggested that the contraction may be controlled by the cytosolic level of Ca2+, since glycerol-extracted Vorticella contracts when Ca2+ is added to the external solution. However, no direct evidence for the increase in cytosolic [Ca2+] has yet been obtained in living Vorticella. In the present study, by injecting a fluorescent Ca2+ indicator into living Vorticella and monitoring the cytosolic [Ca2+] with a confocal microscope, we have demonstrated that a mechanical stimulus evoked an all-or-nothing rise in cytosolic [Ca2+] (Ca2+ 'spike'). The onset of the Ca2+ spike was similar in its time course to that of cellular contraction. Since the Ca2+ spike was recorded in a Ca2+-deprived solution containing 1 mmol l-1 EGTA, we concluded that release of Ca2+ from intracellular Ca2+ storage site(s) is responsible for the Ca2+ spike.
JOURNAL ARTICLE| 01 January 1997
An all-or-nothing rise in cytosolic
Online Issn: 1477-9145
Print Issn: 0022-0949
J Exp Biol (1997) 200 (1): 35–40.
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K Katoh, M Kikuyama; An all-or-nothing rise in cytosolic. J Exp Biol 1 January 1997; 200 (1): 35–40. doi: https://doi.org/10.1242/jeb.200.1.35
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