ELECTRICAL RESPONSES OF THE MARINE CILIATE EUPLOTES-VANNUS (HYPOTRICHIA) TO MECHANICAL STIMULATION AT THE POSTERIOR CELL END

Autor(en): KRUPPEL, T
FURCHBRICH, V
LUEKEN, W
Stichwörter: BEHAVIOR; Biochemistry & Molecular Biology; CA DEPENDENCE; Cell Biology; CURRENTS; DEPENDENT POTASSIUM CHANNEL; EUPLOTES-VANNUS; HYPERPOLARIZATION; K- CURRENT; MEMBRANE; PARAMECIUM-TETRAURELIA; Physiology; POSTERIOR MECHANOSENSITIVITY; PROTOZOA; RECEPTOR POTENTIAL
Erscheinungsdatum: 1993
Herausgeber: SPRINGER
Journal: JOURNAL OF MEMBRANE BIOLOGY
Volumen: 135
Ausgabe: 3
Startseite: 253
Seitenende: 260
Zusammenfassung: 
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.
ISSN: 00222631

Show full item record

Page view(s)

1
Last Week
1
Last month
0
checked on Feb 24, 2024

Google ScholarTM

Check