Nobukuni Ogata

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A variety of different isoforms of voltage-sensitive Na+ channels have now been identified. The recent three-dimensional analysis of Na+ channels has unveiled a unique and unexpected structure of the Na+ channel protein. Na+ channels can be classified into two categories on the basis of their amino acid sequence, Nav1 isoforms currently comprising nine(More)
Small dorsal root ganglion neurons express preferentially the Na+ channel isoform NaV1.9 that mediates a tetrodotoxin-resistant (TTX-R) Na+ current. We investigated properties of the Na+ current mediated by NaV1.9 (INaN) using the whole-cell, patch-clamp recording technique. To isolate INaN from heterogeneous TTX-R Na+ currents that also contain another(More)
Na+ currents and the low-voltage-activated T-type Ca2+ current (T-I Ca) were recorded from neurons of rat dorsal root ganglia under similar ionic environments using the whole-cell patch-clamp technique. Two types of Na+ currents were identified on the basis of their sensitivity to tetrodotoxin (TTX) and channel kinetics. One type was blocked by 1 nM TTX and(More)
Whole-cell patch-clamp experiments were performed with neurons cultured from rat dorsal root ganglia (DRG). Two types of Na+ currents were identified on the basis of sensitivity to tetrodotoxin. One type was blocked by 0.1 nm tetrodotoxin, while the other type was insensitive to 10 μm tetrodotoxin. The peak amplitude of the tetrodotoxin-insensitive Na+(More)
Sensory neurons in the dorsal root ganglion express two kinds of tetrodotoxin resistant (TTX-R) isoforms of voltage-gated sodium channels, Na(V)1.8 and Na(V)1.9. These isoforms play key roles in the pathophysiology of chronic pain. Of special interest is Na(V)1.9: our previous studies revealed a unique property of the Na(V)1.9 current, i.e., the Na(V)1.9(More)
Neurones of the neostriatum were freshly dispersed from the adult guinea pig brain. A fast, transient inward Na+ current (I Na) was analysed using the whole-cell patch-clamp technique. Upon depolarizations, I Na developed with a sigmoidal time course, which was described by m 3 kinetics. I Na showed an activation threshold of about −60 mV, a peak current at(More)
The properties of voltage-gated Na+ channels were studied in neurones isolated from rat dorsal root ganglia using the outside-out configuration of the patch-clamp technique. Two types of single-channel currents were identified from the difference in unit amplitudes. Neither type was evoked in the medium in which extracellular Na+ ions were replaced by an(More)
Small (<25 μm in diameter) neurons of the dorsal root ganglion (DRG) express multiple voltage-gated Na+ channel subtypes, two of which being resistant to tetrodotoxin (TTX). Each subtype mediates Na+ current with distinct kinetic property. However, it is not known how each type of Na+ channel contributes to the generation of action potentials in small DRG(More)
One possible mechanism underlying inflammation-induced sensitization of the primary afferent neuron is the upregulation of tetrodotoxin-resistant (TTX-R) Na(+) current by inflammatory mediators such as prostaglandins. This notion is based on reports that showed an augmentation of TTX-R Na(+) current following an application of prostaglandin E(2) (PGE(2)) in(More)
 The mechanism underlying the enhancement of the high-voltage-activated (HVA) Ca2+ current (I Ca) after application of baclofen, a GABAB agonist, in neurones of the rat dorsal root ganglia was studied by a combined use of the nystatin perforated patch clamp recording and our rapid superfusion system. Baclofen (50 μM) decreased the peak amplitude of HVA I Ca(More)