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Electrical responses of the marine ciliate Euplotes vannus (hypotrichia) to mechanical stimulation at the posterior cell end.
- Source :
-
The Journal of membrane biology [J Membr Biol] 1993 Sep; Vol. 135 (3), pp. 253-60. - Publication Year :
- 1993
-
Abstract
- Electrical responses upon mechanostimulation at the posterior cell end were investigated in the marine hypotrichous ciliate Euplotes vannus. A new mechanostimulator was developed to mimic stimuli that are identical with those involved in cell-cell collisions. The receptor potential hyperpolarized by 18-35 mV within 12-25 msec, reached a peak value of -62 mV with a delay of 4-9 msec after membrane deformation, and was deactivated after 50-70 msec. Cirri were stimulated to beat accelerated backward. The corresponding receptor current exerted a similar time course with a peak of 2.4 nA. The shift of the reversal potential by 57.6 mV at a tenfold increase of [K+]o identifies potassium ions as current carriers within the development of the receptor potential. An intracellular K concentration of 355 mmol/liter was calculated for cells in a medium that was composed similar to sea-water. The mechanically activated potassium current was totally inhibited by extracellular TEA and intracellular Cs+, and partially inhibited by extracellular 4-AP. The total inhibition of the current by injected EGTA points to a Ca dependence of the posterior mechanosensitivity. It was confirmed by the increase of the peak current amplitude with rising [Ca2+]o. Sodium presumably repolarizes the receptor potential because the repolarization was delayed and after-depolarizations were eliminated in media without sodium. Since deciliation did not affect mechanosensitivity, the corresponding ion channels reside within the soma membrane.
- Subjects :
- Animals
Calcium pharmacology
Cell Membrane chemistry
Cell Membrane physiology
Cell Membrane ultrastructure
Cells, Cultured
Dose-Response Relationship, Drug
Egtazic Acid pharmacology
Euplotes ultrastructure
Mechanoreceptors physiology
Quaternary Ammonium Compounds pharmacology
Sodium pharmacology
Euplotes physiology
Membrane Potentials physiology
Stress, Mechanical
Subjects
Details
- Language :
- English
- ISSN :
- 0022-2631
- Volume :
- 135
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- The Journal of membrane biology
- Publication Type :
- Academic Journal
- Accession number :
- 8271265
- Full Text :
- https://doi.org/10.1007/BF00211097