Abstract
The anterior depolarizing mechanoreceptor potential and the correlated receptor currents have been studied in the marine ciliate Euplotes vannus. Mechanical stimuli that mimicked cell-cell collisions depolarized the resting potential of about — 25 mV to maximally — 5 mV, with a speed of 1.2 mV/ms, a delay to the stimulus of about 15 ms, and a repolarization within 30 to 300 ms. The power-stroke direction of the cirri-beat reversed from backward to forward during this response. The receptor current rose to an average amplitude of 1.4 nA with a speed of 0.1–0.3 nA/ms and decayed with a single exponential time course with a time constant between 7 and 9 ms. Similar current-reversal potentials, after substitution of extracellular Ca2+ by Mg2+ and vice versa, indicate that the mechanically activated conductance is identical for Ca2+ or Mg2+. The current can be carried by Ba2+ as well, but not by K+ or Na+. Decirriation experiments have shown that the mechanosensitivity is located within the soma membrane.
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Abbreviations
- EASW :
-
artificial sea-water adapted for electrophysiology
- EGTA :
-
ethylene glycol-O O′-bis(2-aminoethyl)-N′,N,N′,N′-tetraacetic acid
- NMDG :
-
N-methyl-D-glucamine
- TEA :
-
tetraethyl ammonium
- V m :
-
membrane potential
- g X :
-
conductance for the ion X
- D600 :
-
Methoxyverapamil
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Krüppel, T., Rabe, H., Dümmler, B. et al. The depolarizing mechanoreceptor potential and Ca/Mg receptor-current of the marine ciliate Euplotes vannus . J Comp Physiol A 177, 511–517 (1995). https://doi.org/10.1007/BF00187486
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DOI: https://doi.org/10.1007/BF00187486