Elsevier

Neuroscience Letters

Volume 263, Issue 1, 1 March 1999, Pages 57-60
Neuroscience Letters

Distinct ATP-activated currents in different types of neurons dissociated from rat dorsal root ganglion

https://doi.org/10.1016/S0304-3940(99)00114-7Get rights and content

Abstract

Rat dorsal root ganglion neurons can be classified into at least three distinct groups based on cell size, afferent fiber diameter, electrophysiological properties, sensitivity to vanilloid agonists such as capsaicin, and function. In the present study, ATP-activated current in these neurons was characterized using whole-cell patch-clamp recording. Small diameter (<30 μm) cells had high capsaicin sensitivity, high affinity for ATP, and rapidly desensitizing ATP-activated current. Medium diameter (30–50 μm) cells had no capsaicin sensitivity, lower affinity for ATP and slowly desensitizing ATP-activated current. Large diameter (>50 μm) cells were insensitive to both capsaicin and ATP. These findings suggest that distinct types of ATP receptor-ion channels are expressed in different types of dorsal root ganglion neurons, and may contribute to the functional differences among these types of neurons.

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Acknowledgements

We thank Ms. Ke-Ming Xiong for preparation of figures.

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  • Phenotypes of ATP-activated current associated with their genotypes of P2X1-6 subunits in neurons innervating tooth-pulp

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    In situ hybridization and immunohistochemical studies, however, revealed that of the cloned P2X receptor subunits, six (P2X1-P2X6) were expressed in sensory (including TG) neurons [8,9,10,12,13], thus raising the possibility that the native channels, including the channels expressed in nociceptive neurons, may be heteromultimers with diverse composition. Indeed, it has been reported that extracellular ATP can evoke different types of ion current, differing in a number of characteristics, such as current–voltage relationships, agonist and antagonist selectivities, modulation by endogenous agents, and desensitization rate, in nodose ganglion neurons [14,15,16], dorsal root ganglion neurons [17,18,19,20,21], and in TG neurons [3,4,10]. The molecular basis for the different types of ATP-activated current in different types of neuronal preparations, including nociceptive neurons, has not been established.

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