Distribution of N-type Ca2+ channel binding sites in rabbit brain following central administration of ω-conotoxin GVIA

Whorlow, Sarah L.; Loiacono, Richard; Angus, James A.; Wright, Christine E.

doi:10.1016/s0014-2999(96)00592-4

Cited by 15 publications

(5 citation statements)

References 25 publications

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“…Taken together, these data suggest that P/Q‐type channels are little expressed in the somatic and proximal dendritic compartments of PC superficial cells accessible during patch‐clamp recording in isolated neurones, and may perhaps be preferentially targeted to other membrane compartments (axonal or distal dendritic), also in consideration of the well‐established role of P/Q‐type channels in neurotransmission (Uchitel et al 1992; Takahashi & Momiyama, 1993). Finally, our findings on L‐ and N‐type current expression in PC are in agreement with binding and immunohistochemical studies carried out with specific drugs and antibodies (Kerr et al 1988; Chin et al 1992; Whorlow et al 1996).…”

Section: Discussionsupporting

confidence: 90%

Biophysical and pharmacological diversity of high‐voltage‐activated calcium currents in layer II neurones of guinea‐pig piriform cortex

Magistretti

Brevi

Curtis

1999

The Journal of Physiology

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Voltage-activated calcium currents (VACCs) have a primary role in regulating membrane electrophysiological behaviour, intercellular communication and other non-membranal cell functions in neurones (Llin as, 1988; Berridge, 1998). VACCs can influence neuronal electroresponsiveness both directly, by sustaining inward currents that promote depolarizing responses, and indirectly, by recruiting calcium-dependent currents. The kinetic properties and the voltage range of activation of the underlying calcium conductances are key elements in determining the specific contribution of the various VACC types in neuronal functions. For instance, a calcium current activated at more negative voltage levels than another one of similar size will have a stronger depolarizing effect on neuronal membrane: at relatively negative voltage levels, indeed, a higher membrane input resistance and a lesser weight of repolarizing potassium currents due to a smaller driving force for potassium ions are to be expected. The characterization of the calcium currents expressed by a given neuronal type can therefore be relevant to the understanding of its specific functional behaviour. 1. High-voltage-activated calcium currents were studied with the whole-cell, patch-clamp technique in acutely dissociated pyramidal neurones from guinea-pig piriform cortex layer II. Barium ions were used as charge carriers. 2. Barium currents (IBa) displayed a remarkable kinetic diversity in different neurones. The ratio between the current amplitude at the end of the test pulses and the peak amplitude (ReÏp) showed two frequency-distribution peaks at approximately 0·4 and 0·8. The index of current activation speed (rise time 10-90%) directly correlated with the index of current persistence, ReÏp. 3. The half-activation potential (V½) of total IBas positively correlated with the ReÏp of the corresponding currents. This implied that the high-decay IBas also had a more negative voltage range of activation than the more persistent ones. 4. The Land N-type channel blockers nifedipine (10 ìÒ) and ù-conotoxin GVIA (ù_CTx GVIA, 0·5-1 ìÒ) additively blocked 20 and 25% of the total IBa, respectively. The PÏQ-type calcium channel blockers ù-agatoxin IVA (100 nÒ), ù-conotoxin MVIIC (1 ìÒ) and 3.3 funnel toxin (1 ìÒ), had little effect on IBa. 5. The nifedipine-and ù-CTx GVIA-sensitive current had a ReÏp > 0·55 and their voltage dependence of activation was of the high-voltage-activated type (V½ 0 mV). 6. High-, intermediate-and low-decay blocker-resistant currents were observed in different neurones. Their ReÏp values highly correlated with those of the corresponding total IBas and with the voltage dependence of activation of the underlying conductances. Exponential fittings of the inactivation phase of blocker-resistant currents returned very fast time constants (lower than 30 ms) for high-decay currents (ReÏp < 0·25). The intermediate-decay currents (ReÏp 0·55) could not derive from variable combinations of high-and low-decay current components. 7. Our data demonstrate a rem...

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Section: Discussionsupporting

confidence: 90%

Biophysical and pharmacological diversity of high‐voltage‐activated calcium currents in layer II neurones of guinea‐pig piriform cortex

Magistretti

Brevi

Curtis

1999

The Journal of Physiology

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“…(-)-Bay K8644 was dissolved in ethanol 5% in distilled water, and verapamil and bradykinin in methanol 2% in distilled water. Dose ranges were selected according to previous studies (Laurent et al 1987;Dar 1988;Bourson et al 1989;Shapira et al 1990;Basilico et al 1992;Smith and Stevens 1995;Whorlow et al 1996;Suh et al 1997;Czarnecka et al 1998;Smith et al1999;Murzenok et al 2000).…”

Section: Animalsmentioning

confidence: 99%

The antidepressant-like effect induced by the sigma1 (σ1) receptor agonist igmesine involves modulation of intracellular calcium mobilization

et al. 2002

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“…Among three types of VDCCs, P͞Q-type, N-type, and R-type, predominantly expressed in neuronal cells (1,2), N-type Ca 2ϩ channels have been recognized as high-voltage-activated Ca 2ϩ channels selectively sensitive to blockade by -conotoxin GVIA (-CTX), a 27-amino acid peptide isolated from the venom of the fish-hunting cone snail Conus geographus, but resistant to the L-type Ca 2ϩ channelspecific blockers such as dihydropyridines. Molecular studies have revealed that the ␣ 1B (Ca v 2.2) subunit gene encodes N-type Ca 2ϩ channels and is expressed widely in neuronal tissues (3)(4)(5)(6)(7)(8)(9)(10)(11)(12). Experiments employing -CTX have demonstrated the physiological significance of the N-type Ca 2ϩ channels in the nervous system, where they have a specific developmental role in the migration of immature neurons before the establishment of their synaptic circuit (13).…”

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confidence: 99%

Functional disorders of the sympathetic nervous system in mice lacking the α _1B subunit (Ca _v 2.2) of N-type calcium channels

Ino

Yoshinaga

Wakamori

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

129

112

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N-type voltage-dependent Ca 2؉ channels (VDCCs), predominantly localized in the nervous system, have been considered to play an essential role in a variety of neuronal functions, including neurotransmitter release at sympathetic nerve terminals. As a direct approach to elucidating the physiological significance of N-type VDCCs, we have generated mice genetically deficient in the ␣1B subunit (Cav 2.2). The ␣1B-deficient null mice, surprisingly, have a normal life span and are free from apparent behavioral defects. A complete and selective elimination of N-type currents, sensitive to -conotoxin GVIA, was observed without significant changes in the activity of other VDCC types in neuronal preparations of mutant mice. The baroreflex response, mediated by the sympathetic nervous system, was markedly reduced after bilateral carotid occlusion. In isolated left atria prepared from N-type-deficient mice, the positive inotropic responses to electrical sympathetic neuronal stimulation were dramatically decreased compared with those of normal mice. In contrast, parasympathetic nervous activity in the mutant mice was nearly identical to that of wild-type mice. Interestingly, the mutant mice showed sustained elevation of heart rate and blood pressure. These results provide direct evidence that N-type VDCCs are indispensable for the function of the sympathetic nervous system in circulatory regulation and indicate that N-type VDCC-deficient mice will be a useful model for studying disorders attributable to sympathetic nerve dysfunction. V oltage-dependent Ca 2ϩ channels (VDCCs) mediate calcium entry into cells, which is essential for a wide variety of physiological functions. Among three types of VDCCs, P͞Q-type, N-type, and R-type, predominantly expressed in neuronal cells (1, 2), N-type Ca 2ϩ channels have been recognized as high-voltage-activated Ca 2ϩ channels selectively sensitive to blockade by -conotoxin GVIA (-CTX), a 27-amino acid peptide isolated from the venom of the fish-hunting cone snail Conus geographus, but resistant to the L-type Ca 2ϩ channelspecific blockers such as dihydropyridines. Molecular studies have revealed that the ␣ 1B (Ca v 2.2) subunit gene encodes N-type Ca 2ϩ channels and is expressed widely in neuronal tissues (3-12). Experiments employing -CTX have demonstrated the physiological significance of the N-type Ca 2ϩ channels in the nervous system, where they have a specific developmental role in the migration of immature neurons before the establishment of their synaptic circuit (13). N-type Ca 2ϩ channels have been shown to be critically involved in the release of neurotransmitters, including glutamate (14-16), ␥-aminobutyric acid (14), acetylcholine (17), dopamine (18)(19)(20), and norepinephrine (21) in mammalian central neurons. For instance, in CA1 hippocampal neurons, the inhibitory GABAergic synaptic potentials are reduced by 85-90% by saturating concentrations of -CTX, whereas the excitatory glutaminergic transmission is blocked by 65-70% (16).In peripheral neurons such as autonomic neurons...

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Distribution of N-type Ca2+ channel binding sites in rabbit brain following central administration of ω-conotoxin GVIA

Cited by 15 publications

References 25 publications

Biophysical and pharmacological diversity of high‐voltage‐activated calcium currents in layer II neurones of guinea‐pig piriform cortex

Biophysical and pharmacological diversity of high‐voltage‐activated calcium currents in layer II neurones of guinea‐pig piriform cortex

The antidepressant-like effect induced by the sigma1 (σ1) receptor agonist igmesine involves modulation of intracellular calcium mobilization

Functional disorders of the sympathetic nervous system in mice lacking the α _1B subunit (Ca _v 2.2) of N-type calcium channels

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Distribution of N-type Ca2+ channel binding sites in rabbit brain following central administration of ω-conotoxin GVIA

Cited by 15 publications

References 25 publications

Biophysical and pharmacological diversity of high‐voltage‐activated calcium currents in layer II neurones of guinea‐pig piriform cortex

Biophysical and pharmacological diversity of high‐voltage‐activated calcium currents in layer II neurones of guinea‐pig piriform cortex

The antidepressant-like effect induced by the sigma1 (σ1) receptor agonist igmesine involves modulation of intracellular calcium mobilization

Functional disorders of the sympathetic nervous system in mice lacking the α 1B subunit (Ca v 2.2) of N-type calcium channels

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Product

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Functional disorders of the sympathetic nervous system in mice lacking the α _1B subunit (Ca _v 2.2) of N-type calcium channels