Two types of calcium channels sensitive to ω-agatoxin-TK in cultured rat hippocampal neurones

Teramoto, Takashi; Niidome, Takuro; Miyagawa, Takehiko; Nishizawa, Yuji; Katayama, Kohta; Sawada, Kouhei

doi:10.1097/00001756-199508000-00022

Cited by 43 publications

(35 citation statements)

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“…Here we have demonstrated that sighs were abolished selectively at an MVIIC concentration of 100 nM, suggesting a Q-type pharmacology (McDonough et al 1996;Randall and Tsien 1995;Sather et al 1993). On the other hand, the blockade of sighs in some preparations at Aga-TK concentrations as low as 15 nM is more consistent with a P-type pharmacology (Mintz et al 1992;Randall and Tsien 1995;Teramoto et al 1995). It therefore seems most appropriate to consider the channels responsible as "P/Q type," at the population level as well with an indeterminate-and possibly variable-pharmacological phenotype.…”

Section: Population Level Effects: P or Q Type?supporting

confidence: 56%

“…The remaining calcium influx is presumably carried by a combination of R-type (␣ 1E ) channels, and ␣ 1A channels with a lower sensitivity to agatoxin, either Q-type channels (McDonough et al 1996;Randall and Tsien 1995;Teramoto et al 1995) or ␣ 1A channels with properties intermediate between the classical P-and Q-phenotypes (Forsythe et al 1998;Stea et al 1994;Tottene et al 1996).…”

Section: Presynaptic Ca 2ϩ Channels In the Respiratory Networkmentioning

confidence: 99%

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Pattern-Specific Synaptic Mechanisms in a Multifunctional Network. I. Effects of Alterations in Synapse Strength

Lieske¹,

Ramirez²

2006

Journal of Neurophysiology

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. Pattern-specific synaptic mechanisms in a multifunctional network. I. Effects of alterations in synapse strength. J Neurophysiol 95: 1323-1333, 2006; doi:10.1152/jn.00505.2004. Many neuronal networks are multifunctional, producing different patterns of activity in different circumstances, but the mechanisms responsible for this reconfiguration are in many cases unresolved. The mammalian respiratory network is an example of such a system. Normal respiratory activity (eupnea) is periodically interrupted by distinct large-amplitude inspirations known as sighs. Both rhythms originate from a single multifunctional neural network, and both are preserved in the in vitro transverse medullary slice of mice. Here we show that the generation of fictive sighs were more sensitive than eupnea to reductions of excitatory synapse strength caused by either the P/Q-type (␣ 1A -containing) calcium channel antagonist -agatoxin TK or the non-N-methyl-Daspartate (NMDA) glutamate receptor antagonist 6-cyano-7-nitroquinoxalene-2,3-dione (CNQX). In contrast, the NMDA receptor antagonist MK-801, while also inhibiting eupnea, increased the occurrence of sighs. This suggests that among the glutamatergic synapses subserving eupneic rhythmogenesis, there is a specific subset-highly sensitive to agatoxin and insensitive to NMDA receptor blockadethat is essential for sighs. Blockade of N-type calcium channels with -conotoxin GVIA also had pattern-specific effects: eupneic activity was not affected, but sigh frequency was increased and postsigh apnea decreased. We hypothesize that N-type (␣ 1B ) calcium channels selectively coupled to calcium-activated potassium channels contribute to the generation of the postsigh apnea.

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Section: Population Level Effects: P or Q Type?supporting

confidence: 56%

Section: Presynaptic Ca 2ϩ Channels In the Respiratory Networkmentioning

confidence: 99%

Pattern-Specific Synaptic Mechanisms in a Multifunctional Network. I. Effects of Alterations in Synapse Strength

Lieske¹,

Ramirez²

2006

Journal of Neurophysiology

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“…The -agatoxin-sensitive current did not show significant inactivation (e.g., Fig. 4A 2 ), suggesting that R-B neurons possess many more P-type channels than Q-type channels (Teramoto et al, 1995). Nifedipine (10 M) did not block the HVA currents in three of eight R-B neurons and blocked only very small amounts of the HVA current in the other five neurons (mean block 5.5 Ϯ 1.8%, p Ͼ 0.1 vs control; Fig.…”

Section: Hva Calcium Channel Identitymentioning

confidence: 95%

“…To identify further the HVA channel types possessed by Xenopus R-B neurons, we used -conotoxin, fraction GVIA (-CgTx), which is a selective N-type Ca 2ϩ channel blocker (Feldman et al, 1987), -agatoxin-TK, which is a P/Q-type channel blocker (Teramoto et al, 1995), and nifedipine, a selective blocker of L-type channels. -CgTx (1 M) irreversibly blocked 70.4 Ϯ 2.8% (n ϭ 16) of the HVA currents (Fig.…”

Section: Hva Calcium Channel Identitymentioning

confidence: 99%

Serotonergic Inhibition of the T-Type and High Voltage-Activated Ca²⁺Currents in the Primary Sensory Neurons ofXenopusLarvae

Sun

Dale

1997

J. Neurosci.

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The primary sensory Rohon-Beard (R-B) neurons of Xenopus larvae are highly analogous to the C fibers of the mammalian pain pathway. We explored the actions of 5-HT by studying the modulation of Ca 2ϩ currents. In ϳ80% of the acutely isolated R-B neurons, 5-HT inhibited the high voltage-activated (HVA) currents by 16% (n ϭ 29) and the T-type currents by 24% (n ϭ 41). The modulation of the T-type and the HVA currents was mimicked by selective 5-HT 1A and 5-HT 1D agonists: 8-OH-DPAT and L-694,247. The effects of the agonists were blocked by their respective 5-HT 1A or 5-HT 1D antagonists: p-MPPI and GR127935, suggesting that both 5-HT 1A and 5-HT 1D receptors were involved. Approximately 70% of the actions of 5-HT on HVA currents was occluded by -conotoxin-GVIA (N-type channel blocker), whereas the rest of the modulation (ϳ30%) was occluded by Ͻ100 nM -agatoxin-TK (P/Q-type channel blocker). This suggests that 5-HT acts on N-and P/Q-type Ca 2ϩ channels. Neither the modulation of the T-type nor that of the HVA currents was accompanied by changes in their voltage-dependent kinetics. Cell-attached patch-clamp recordings suggest that the modulation of the T-type channel occurs through a membrane-delimited second messenger. We have studied the functional consequences of the modulation of T-type Ca 2ϩ channels and have found that these channels play a role in spike initiation in R-B neurons. Modulation of T-type channels by 5-HT therefore could modulate the sensitivity of this sensory pathway by increasing the thresholds of R-B neurons. This is a new and potentially important locus for modulation of sensory pathways in vertebrates.

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“…2+ influx Electrophysiological and pharmaceutical studies in vertebrate neurons have shown that the VGCCs can be classified into several types (Nowycky et al, 1985;Regan, 1991;Teramoto et al, 1995). Moreover, the same pharmaceutical agents have been demonstrated to be applicable to classify the VGCCs in invertebrate neurons (Edmonds et al, 1990;Fossier et al, 1994;Ma and Koester, 1995).…”

Section: Types Of Vgccs Contributing To Camentioning

confidence: 99%

Calcium Imaging for Detection and Estimation of Spike Activities in Aplysia Neurons

Yoshida¹,

Iwamoto²,

Nagahama³

2001

Zoological Science

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Two types of calcium channels sensitive to ω-agatoxin-TK in cultured rat hippocampal neurones

Cited by 43 publications

References 0 publications

Pattern-Specific Synaptic Mechanisms in a Multifunctional Network. I. Effects of Alterations in Synapse Strength

Pattern-Specific Synaptic Mechanisms in a Multifunctional Network. I. Effects of Alterations in Synapse Strength

Serotonergic Inhibition of the T-Type and High Voltage-Activated Ca²⁺Currents in the Primary Sensory Neurons ofXenopusLarvae

Calcium Imaging for Detection and Estimation of Spike Activities in Aplysia Neurons

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Two types of calcium channels sensitive to ω-agatoxin-TK in cultured rat hippocampal neurones

Cited by 43 publications

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Pattern-Specific Synaptic Mechanisms in a Multifunctional Network. I. Effects of Alterations in Synapse Strength

Pattern-Specific Synaptic Mechanisms in a Multifunctional Network. I. Effects of Alterations in Synapse Strength

Serotonergic Inhibition of the T-Type and High Voltage-Activated Ca2+Currents in the Primary Sensory Neurons ofXenopusLarvae

Calcium Imaging for Detection and Estimation of Spike Activities in Aplysia Neurons

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Serotonergic Inhibition of the T-Type and High Voltage-Activated Ca²⁺Currents in the Primary Sensory Neurons ofXenopusLarvae