Direct influence of the sodium pump on the membrane potential of vomeronasal chemoreceptor neurones in frog.

Trotier, Didier; Døving, Kjell B.

doi:10.1113/jphysiol.1996.sp021171

Cited by 35 publications

(19 citation statements)

References 20 publications

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“…4 Ec). This relation is consistent with the I-V relationship of Na ϩ -K ϩ pump currents (Chapman et al, 1983;Gadsby and Nakao, 1989;Trotier and Doving, 1996). The mean amplitude of such a steady I p at Ϫ50 mV obtained in the presence of 5 mM Cs ϩ in addition to 3 mM K ϩ was 47.8 Ϯ 11.6 pA (n ϭ 5).…”

Section: Cssupporting

confidence: 71%

“…4 Ab,Ac). Both the fast and slow outward currents increased with an increase of the negative command pulse, contrary to the behavior expected from the I-V relationship of the I p (Chapman et al, 1983;Gadsby and Nakao, 1989;Trotier and Doving, 1996). In contrast, in response to the test pulses without the prepulse (Fig.…”

Section: Cscontrasting

confidence: 42%

“…Then, it is not possible for the offset of the depolarizing current pulse to electrotonically cause such a large pulse-AHP. Because the negative peak level of pulse-AHP far exceeded the equilibrium potential for K ϩ ions (Ϫ97 mV), the pulse-AHP is most likely to be accounted for by the activity of the Na ϩ -K ϩ pump, the reversal potential of which is more negative than Ϫ150 to Ϫ200 mV (Chapman et al, 1983;Gadsby and Nakao, 1989;Trotier and Doving, 1996). To test this possibility, we applied ouabain, an inhibitor of the Na ϩ -K ϩ pump.…”

Section: Resultsmentioning

confidence: 99%

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Bidirectional Interactions between H-Channels and Na⁺–K⁺Pumps in Mesencephalic Trigeminal Neurons

Kang¹,

Notomi²,

Saito³

et al. 2004

J. Neurosci.

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The Na ϩ -K ϩ pump current (I p ) and the h-current (I h ) flowing through hyperpolarization-activated channels (h-channels) participate in generating the resting potential. These two currents are thought to be produced independently. We show here bidirectional interactions between Na ϩ -K ϩ pumps and h-channels in mesencephalic trigeminal neurons. Activation of I h leads to the generation of two types of ouabain-sensitive I p with temporal profiles similar to those of instantaneous and slow components of I h , presumably reflecting Na ϩ transients in a restricted cellular space. Moreover, the I p activated by instantaneous I h can facilitate the subsequent activation of slow I h . Such counteractive and cooperative interactions were also disclosed by replacing extracellular Na ϩ with Li ϩ , which is permeant through h-channels but does not stimulate the Na ϩ -K ϩ pump as strongly as Na ϩ ions. These observations indicate that the interactions are bidirectional and mediated by Na ϩ ions. Also after substitution of extracellular Na ϩ with Li ϩ , the tail I h was reduced markedly despite an enhancement of I h itself, attributable to a negative shift of the reversal potential for I h presumably caused by intracellular accumulation of Li ϩ ions. This suggests the presence of a microdomain where the interactions can take place. Thus, the bidirectional interactions between Na ϩ -K ϩ pumps and h-channels are likely to be mediated by Na ϩ microdomain. Consistent with these findings, hyperpolarization-activated and cyclic nucleotide-modulated subunits (HCN1/2) and the Na ϩ -K ϩ pump ␣3 isoform were colocalized in plasma membrane of mesencephalic trigeminal neurons having numerous spines.

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Section: Cssupporting

confidence: 71%

Section: Cscontrasting

confidence: 42%

Section: Resultsmentioning

confidence: 99%

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Bidirectional Interactions between H-Channels and Na⁺–K⁺Pumps in Mesencephalic Trigeminal Neurons

Kang¹,

Notomi²,

Saito³

et al. 2004

J. Neurosci.

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show abstract

“…In many such cells, blockage of the pump results in very little change in membrane potential [38]. In the other extreme, some neurons depend almost exclusively on the pump activity to polarize the membrane [40]. Our present results show that the PC potential is also very sensitive to pump activity and that the continuously active pump may produce a current which compensates for a depolarizing, continuous influx of Na + into the cell.…”

Section: Possible Origins Of a Na + Influxmentioning

confidence: 68%

Hyperpolarizing current of the Na/K ATPase contributes to the membrane polarization of the Purkinje cell in rat cerebellum

Genet

Kado

1997

Pfl�gers Archiv European Journal of Physiology

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The contribution of the Na/K ATPase (pump) current to the polarization of the Purkinje cell has been studied using slices of the rat cerebellum by blocking the pump with dihydro-ouabain (DHO) while recording the membrane potential with microelectrodes in the somata. From our recordings, it appeared that blocking the pump depolarized the Purkinje cells more rapidly than might be expected from shifts in Na+ and K+ concentrations, suggesting the removal of a hyperpolarizing current. Application of DHO, in the presence of tetrodotoxin (TTX), led to calcium spike firing and plateau-like discharges suggesting activation of voltage-dependent calcium channels in the dendrites. Adding 2 mM CO2+ to the medium did not prevent the depolarizations. Removing calcium from the bathing medium containing 2 mM CO2+ blocked the spiking activity but DHO application still produced a depolarization. Experiments to measure the current inhibited by DHO indicated that the Na/K pump supplies a constant current of 240 pA. Substitution of the sodium with choline produced a hyperpolarization, during which DHO had no effect on the membrane potential. Substitution of the sodium with lithium produced only a slowly developing depolarization. It is concluded that in the cerebellar Purkinje cell, a continuous sodium ion influx activates the pumps which produce a current that directly contributes to the membrane polarization. Possible pathways for this sodium influx are discussed.

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“…Potassium channels, including M-channels, inward rectifiers, and TASK channels, tend to bring resting potentials toward E K (Marrion, 1997;Reimann and Ashcroft, 1999;Millar et al, 2000); in several cell types the Na/K pump also serves to hyperpolarize resting potentials (Jacob et al, 1987;Jones, 1989;Trotier and Døving, 1996). Many neurons rest positive to E K , however, indicating that inward currents also must be active at rest (Forsythe and Redman, 1988;Jones, 1989).…”

Section: Currents That Determine the Resting Potentialmentioning

confidence: 99%

Ionic Currents and Spontaneous Firing in Neurons Isolated from the Cerebellar Nuclei

2000

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Neurons of the cerebellar nuclei fire spontaneous action potentials both in vitro, with synaptic transmission blocked, and in vivo, in resting animals, despite ongoing inhibition from spontaneously active Purkinje neurons. We have studied the intrinsic currents of cerebellar nuclear neurons isolated from the mouse, with an interest in understanding how these currents generate spontaneous activity in the absence of synaptic input as well as how they allow firing to continue during basal levels of inhibition. Current-clamped isolated neurons fired regularly (ϳ20 Hz), with shallow interspike hyperpolarizations (approximately Ϫ60 mV), much like neurons in more intact preparations. The spontaneous firing frequency lay in the middle of the dynamic range of the neurons and could be modulated up or down with small current injections.During step or action potential waveform voltage-clamp commands, the primary current active at interspike potentials was a tetrodotoxin-insensitive (TTX), cesium-insensitive, voltageindependent, cationic flux carried mainly by sodium ions. Although small, this cation current could depolarize neurons above threshold voltages. Voltage-and current-clamp recordings suggested a high level of inactivation of the TTX-sensitive transient sodium currents that supported action potentials. Blocking calcium currents terminated firing by preventing repolarization to normal interspike potentials, suggesting a significant role for K(Ca) currents. Potassium currents that flowed during action potential waveform voltage commands had high activation thresholds and were sensitive to 1 mM TEA. We propose that, after the decay of high-threshold potassium currents, the tonic cation current contributes strongly to the depolarization of neurons above threshold, thus maintaining the cycle of firing.

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Direct influence of the sodium pump on the membrane potential of vomeronasal chemoreceptor neurones in frog.

Cited by 35 publications

References 20 publications

Bidirectional Interactions between H-Channels and Na⁺–K⁺Pumps in Mesencephalic Trigeminal Neurons

Bidirectional Interactions between H-Channels and Na⁺–K⁺Pumps in Mesencephalic Trigeminal Neurons

Hyperpolarizing current of the Na/K ATPase contributes to the membrane polarization of the Purkinje cell in rat cerebellum

Ionic Currents and Spontaneous Firing in Neurons Isolated from the Cerebellar Nuclei

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Direct influence of the sodium pump on the membrane potential of vomeronasal chemoreceptor neurones in frog.

Cited by 35 publications

References 20 publications

Bidirectional Interactions between H-Channels and Na+–K+Pumps in Mesencephalic Trigeminal Neurons

Bidirectional Interactions between H-Channels and Na+–K+Pumps in Mesencephalic Trigeminal Neurons

Hyperpolarizing current of the Na/K ATPase contributes to the membrane polarization of the Purkinje cell in rat cerebellum

Ionic Currents and Spontaneous Firing in Neurons Isolated from the Cerebellar Nuclei

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Product

Resources

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Bidirectional Interactions between H-Channels and Na⁺–K⁺Pumps in Mesencephalic Trigeminal Neurons

Bidirectional Interactions between H-Channels and Na⁺–K⁺Pumps in Mesencephalic Trigeminal Neurons