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  • 1975-1979  (6)
  • 1965-1969  (1)
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  • 1
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    Are receptor-activated ciliary motor responses mediated through voltage or current? (1978)
    Springer Nature
    Details
    Publication Date: 1978-11-01
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Springer Nature
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  • 2
    Electronic Resource
    Electronic Resource
    Regulation der Cilienmetachronie bei der “Fluchtreaktion” von Paramecium (1969)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 16 (1969), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. Paramecia induced to perform high rates of avoiding reactions by mechanical stimulation and the action of Ba ions were instantaneously fixed with OsO4. Quantitative evaluation of the preparations revealed, among other things, metachronal stages of the transition between the ciliary patterns of swimming backward and forward. In each of the transitory stages, metachronal waves of swimming forward were found at the anterior end and waves of swimming backward at the posterior end of the animal. This confirms the so-called Párducz-scheme of avoiding reaction for the case of homogeneous chemical stimulation as well as for mechanical stimulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1969.tb02340.x
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  • 3
    Electronic Resource
    Electronic Resource
    Are receptor-activated ciliary motor responses mediated through voltage or current? (1978)
    [s.l.] : Nature Publishing Group
    Nature 276 (1978), S. 285-287 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fig. 1 Stylonychia mytilus, as orientated in the experimental set-up for cinematographic (16mm, 250f.p.s.) and electrophy-siological recording, a, Cell in oblique dorsal view with right marginal cirri (Cmr) focused under a compound microscope (Zeiss interference contrast). Vertical oscilloscope ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/276285a0
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  • 4
    Electronic Resource
    Electronic Resource
    Modification of ciliary activity by the rate of membrane potential changes inParamecium (1975)
    Springer
    Journal of comparative physiology 101 (1975), S. 343-356 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The sequence of ciliary responses inParamecium to shifts in membrane potential is rate-dependent. With depolarizations exceeding the rate of 40mV · sec−1 the cilia switch directly from normal to reversed beating, thereby rapidly increasing their frequency. If the membrane is depolarized at the rate of 40 mV · sec−1 or less, unabbreviated ciliary responses occur with the sequence: reduction in normal beating → inactivation → increase in reversed beating. This “typical”, since potential-correlated, sequence is at least 50 times slower than the preceding electric membrane response. A time-dependent hysteresis of current versus voltage during depolarizing and hyperpolarizing slow voltage ramps suggests membrane accommodation mechanisms. A slow inactivation of inward calcium current during depolarization and a slow decrease in Ca-conductance during hyperpolarization is suggested from a hysteresis of the frequency response versus voltage. Differences in local ciliary responses to slow voltage ramps are interpreted as generated by modified local Ca-conductances. It is concluded that the graded frequency and directional responses of the cilia are correlated with the time-course of calcium accumulation and depletion within the cilium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00657050
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  • 5
    Electronic Resource
    Electronic Resource
    Membrane excitability inStylonychia: Properties of the two-peak regenerative Ca-response (1977)
    Springer
    Journal of comparative physiology 121 (1977), S. 15-32 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Spontaneous or stimulus-induced membrane depolarizations inStylonychia reveal two components of the action potential, a fast (peak I) and a slow response (peak II). Current stimuli of sufficient magnitude to evoke maximal responses (3×10−8A, 2 ms) were given to characterize the time-, voltage- and ion-dependence of both regenerative components. The threshold voltage is 2–3 mV above resting potential. Peak I is graded with stimulus intensity, peak II is all-or-none reaching commonly less than 1/2 of peak I maximal amplitude. The refractoriness of peak II exceeds that of peak I at given stimulus intervals. Refractory periods of both components decrease with increased stimulus strength. Depolarizing prepulses depress peak II prior to a depression of peak I, the latter being more sensitive than peak II to depression by hyperpolarizing current conditioning. Increasing [K]0 with constant [Ca]0 leaves peak potentials I and II largely unaffected. Rising [Ca]0 at constant [K]0 increases peak potentials I by 17 mV, peak potentials II by 10 mV per 10-fold increase in [Ca]0. Replacement of chloride by nitrate or propionate indicates no contribution to the membrane potential of chloride. Considerations of the calcium/potassium conductance ratios suggest that both components of the regenerative response arise from potential-dependent inward calcium fluxes which are strongly shortcircuited by outward fluxes of potassium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00614178
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  • 6
    Electronic Resource
    Electronic Resource
    Hyperpolarizing and depolarizing mechanoreceptor potentials inStylonychia (1978)
    Springer
    Journal of comparative physiology 127 (1978), S. 255-266 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The surface ofStylonychia was mechanically stimulated with a piezo-crystal driven microneedle of 0.5-2 μm distal diameter and maximal amplitudes of 13 μm. Stimulation of the anterior surface of the cell produced a membrane depolarization, while stimulation of the posterior surface elicited a hyperpolarizing response. The analysis of electric responses to mechanical stimuli, driven by pulses varied in duration, amplitude, rate and acceleration, revealed that the hyperpolarizing receptor potential (hRP) rose in parallel with the stimulus velocity. Stimulus amplitudes beyond 12 μm and at rates larger than 4 mm/s did not increase the amplitude of the membrane response. Sustained stimuli slowed down the repolarization to the resting level. Adaptation of the receptor response was seen with small and sustained velocities of the stimulating probe. The depolarizing receptor response (dRP) triggered an action potential consisting of two regenerative components, one graded, the other all-or-none. Positive conditioning current pulses reversed the polarity of the dRP which was primarily Ca-dependent (22.4 mV/log [Ca]0). The dRP was isolated from the action potential by negative membrane conditioning. The reversal potential of the hyperpolarizing receptor response was negative of the resting potential and completely K-dependent (58.5 mV/log [K]o). Submaximal hyperpolarizing and subthreshold depolarizing receptor potentials showed summation. No refractoriness of the hRP was detected. Summation of depolarizing responses beyond the threshold activated a regenerative membrane depolarization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01350116
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  • 7
    Electronic Resource
    Electronic Resource
    Ciliary frequency and orientational responses to clamped voltage steps inParamecium (1975)
    Springer
    Journal of comparative physiology 104 (1975), S. 247-260 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Simultaneous voltage clamping and microcinematography were used to examine the behavior of cilia in response to prolonged hyperpolarizing and depolarizing steps in the membrane potential ofParamecium caudatum. In the absence of stimulation the cilia beat at less than 20 cycles per second with the power stroke directed toward the posterior and somewhat to the right (i.e. 4 o'clock) of the cell. 2. Hyperpolarization of the membrane results in a graded increase in frequency and a slight clockwise shift in orientation of the power stroke to a more posteriad orientation (i.e. toward 6 o'clock); peak frequencies of up to 50/sec are reached in about 4 sec, after which the beating settles to a lower steady frequency. 3. Responses to depolarization are more complex; below +3 to +5 mV the frequency drops toward a minimum. Further depolarization up to +20 mV produces a stimulus graded increase in frequency with a graded counterclockwise shift in orientation of the power stroke. 4. During maintained depolarizations the frequency of reversed beating increases with time over several seconds and then gradually decreases in frequency over a period of 30 to 60 sec during which time the orientation also relaxes toward normally directed beating. 5. With potential shifts of more than +60 mV the frequency of reversed beating becomes less, reaching a minimum between +80 and +100mV; at greater positive potential steps normal beating is reestablished. 6. During 1- to 2-sec steps of either small (1–4 mV) or large (60 to 100 mV) positive potential steps there is a progressive slowing of normally directed beating until the cilia stop and finally exhibit reversed beating. 7. In all instances ciliary orientation and frequency change together in parallel as a function of membrane voltage. Following the first second of stimulation these two parameters of movement also exhibit changes which parallel in time slow changes in current. This suggests a common regulating substance or process. 8. Evidence is discussed which indicates that it is [Ca]in, regulated by the voltage-sensitive calcium conductance of the surface membrane, which is the common agent controlling both the frequency and the direction of ciliary beating.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01379051
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