The Aplysia californica Cl- pump is a P-type ATPase: evidence through inhibition studies

Utilizing a proteoliposomal preparation containing Cl-ATPase from Aplysia californica foregut, it was shown that orthovanodate inhibited Cl-ATPase activity, ATP-dependent Cl transport, ATP-dependent membrane potential change and ATP-dependent phosphorylation. N-ethylmalemide and p-chloromercurobenzoate also inhibited the Cl pump biochemical and physiological transport characteristics. However, bafilomycin, azide, N, N'-dicyclohexylcarboiimide (DCCD), and efrapeptin had no effect on the Cl pump biochemical or physiological characteristics, suggesting that this Cl pump was a P-type ATPase. It was concluded that this P-type ATPase Cl pump is the mechanism that is responsible for the net absorptive flux of Cl in the A. californica foregut.Key words: Cl pump, P-type ATPase, orthovanadate.

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Evoked membrane potential change in rat optic nerve fiber: Computer simulation

Neuroscience Bulletin ◽

10.1007/s12264-007-0052-8 ◽

2007 ◽

Vol 23 (6) ◽

pp. 348-356 ◽

Cited By ~ 1

Author(s):

Vincent Cazenave-Loustalet ◽

Qing-Li Qiao ◽

Li-Ming Li ◽

Qiu-Shi Ren

Keyword(s):

Computer Simulation ◽

Membrane Potential ◽

Optic Nerve ◽

Nerve Fiber ◽

Potential Change ◽

Membrane Potential Change ◽

Optic Nerve Fiber

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Sustained membrane potential change of uropod motor neurons during the fictive abdominal posture movement in crayfish

Journal of Neurophysiology ◽

10.1152/jn.1986.56.3.702 ◽

1986 ◽

Vol 56 (3) ◽

pp. 702-717 ◽

Cited By ~ 11

Author(s):

M. Takahata ◽

M. Hisada

Keyword(s):

Membrane Potential ◽

Motor Neurons ◽

Membrane Resistance ◽

Potential Change ◽

Quiescent State ◽

Membrane Potential Change ◽

Synaptic Potentials ◽

Nonspiking Interneurons ◽

Body Rolling ◽

Dendritic Branches

The occurrence of the uropod steering response as one of the equilibrium reflexes to body rolling in crayfish is significantly facilitated if the stimulus is given while the animal is performing the abdominal posture movement. This facilitation of the descending statocyst pathway by the abdominal posture system takes place between the uropod motor neurons and the statocyst interneurons, which directly project from the brain to the terminal abdominal ganglion where the motor neurons originate. To elucidate the synaptic mechanisms underlying the postural facilitation of the steering response, we analyzed in this study the activity of an identified set of uropod motor neurons during the fictive abdominal extension movement in the whole-animal preparation. Intracellular recordings from the dendritic branches of uropod motor neurons revealed that they were continuously excited during the fictive abdominal extension. The large fast motor neurons usually showed a sustained depolarization of the subthreshold magnitude. The small slow ones showed a suprathreshold sustained depolarization with spikes superimposed. Putative inhibitory motor neurons, on the other hand, showed a sustained hyperpolarization with their spontaneous spike discharge suppressed. The discrete synaptic potentials could hardly be distinguished and, instead, small fluctuations of the membrane potential were observed during the sustained depolarization of both the fast and slow motor neurons. Occasionally, large discrete synaptic potentials could be observed to be superimposed on the sustained depolarization. The occurring frequency of these synaptic potentials showed, however, no significant increase associated with the sustained depolarization. It hence seemed unlikely that these potentials were responsible for producing the sustained depolarization. Their amplitude during the sustained depolarization was smaller than that observed during the quiescent state. The sustained membrane potential change during the fictive abdominal movement was also observed in many neurons other than motor neurons, including local nonspiking interneurons and mechanosensory spiking interneurons. Both motor neurons and interneurons showed a decrease in their membrane resistance during the sustained membrane potential change. We concluded that the sustained depolarization of uropod motor neurons during the fictive abdominal extension was produced by the summation of small chemically transmitted postsynaptic potentials.(ABSTRACT TRUNCATED AT 400 WORDS)

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