title: Repetitive Ca2+ spikes in a unicellular green alga.
abstract: Cytosolic Ca2+ activity ([Ca2+]cy) and membrane potential were measured simultaneously in the unicellular green alga Eremosphaera viridis. Steady state [Ca2+]cy was about 160 nM. A 'light-off' stimulus induced a transient elevation of [Ca2+]cy ([Ca2+]cy spike) in parallel with a transient hyperpolarization of the plasma membrane. Caffeine and Sr2+, known to release Ca2+ from intracellular stores in animal cells, induced repetitive [Ca2+]cy spikes in Eremosphaera which were always accompanied by parallel repetitive transient hyperpolarizations. These transient hyperpolarizations could be used as an indicator for [Ca2+]cy spikes. Repetitive [Ca2+]cy spikes in Eremosphaera were similar to repetitive [Ca2+]cy spikes in excitable animal cells. The mechanisms underlying these [Ca2+]cy oscillations seem to be comparable in animal and plant cells.
authors.affiliation: Lehrstuhl Botanik I, Universität Würzburg, Germany.
authors.forename: C S
authors.initials: CS
authors.lastname: Bauer
authors.forename: C
authors.initials: C
authors.lastname: Plieth
authors.forename: U P
authors.initials: UP
authors.lastname: Hansen
authors.forename: B
authors.initials: B
authors.lastname: Sattelmacher
authors.forename: W
authors.initials: W
authors.lastname: Simonis
authors.forename: G
authors.initials: G
authors.lastname: Schönknecht
mesh_terms: D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology / Q000502:physiology*; D000460:Chlorophyta; D003600:Cytosol / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects; D010507:Periodicity
chemical_list: D002110:Caffeine; D002118:Calcium