Abstract.
The concentration of intracellular calcium, [Ca2+] i , in Paramecium was imaged during cold-sensitive response by monitoring fluorescence of two calcium-sensitive dyes, Fluo-3 and Fura-Red. Cooling of a deciliated Paramecium caused a transient increase in [Ca2+] i at the anterior region of the cell. Increase in [Ca2+] i was not observed at any region in Ca2+-free solution. Under the electrophysiological recording, a transient depolarization of the cell was observed in response to cooling. On the voltage-clamped cell, cooling induced a transient inward current under conditions where K+ currents were suppressed. These membrane depolarizations and inward currents in response to cooling were lost upon removing extracellular Ca2+. The cold-induced inward current was lost upon replacing extracellular Ca2+ with equimolar concentration of Co2+, Mg2+ or Mn2+, but it was not affected significantly by replacing with equimolar concentration of Ba2+ or Sr2+. These results indicate that Paramecium cells have Ca2+ channels that are permeable to Ca2+, Ba2+ and Sr2+ in the anterior soma membrane and the channels are opened by cooling.
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Received: 1 April 1996/Revised: 23 July 1996
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Kuriu, T., Nakaoka, Y. & Oosawa, Y. Cold-sensitive Ca2+ Influx in Paramecium . J. Membrane Biol. 154, 163–167 (1996). https://doi.org/10.1007/s002329900141
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DOI: https://doi.org/10.1007/s002329900141