Few cultured rat primary sensory neurons express a tolbutamide-sensitive K+ current |
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Authors: | Ristoiu Violeta Pluteanu Florentina Flonta Maria-Luiza Reid G |
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Affiliation: | Department of Animal Physiology and Biophysics, Faculty of Biology, University of Bucharest, Bucharest, Romania |
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Abstract: | The response of dorsal root ganglion (DRG) neurons to metabolic inhibition is known to involve calcium-activated K+ channels; in most neuronal types ATP-sensitive K+ channels (KATP) also contribute, but this is not yet established in the DRG. We have investigated the presence of a KATP current using whole-cell recordings from rat DRG neurons, classifying the neurons functionally by their "current signature" (Petruska et al, J Neurophysiol 84: 2365–2379, 2000). We clearly identified a KATP current in only 1 out of 62 neurons, probably a nociceptor. The current was activated by cyanide (2 mM NaCN) and was sensitive to 100 μM tolbutamide; the relation between reversal potential and external K+ concentration indicated it was a K+ current. In a further two neurons, cyanide activated a K+ current that was only partially blocked by tolbutamide, which may also be an atypical KATP current. We conclude that KATP channels are expressed in normal DRG, but in very few neurons and only in nociceptors. |
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Keywords: | tolbutamide ATP-sensitive K+ (KATP) channel metabolic inhibition primary sensory neuron dorsal root ganglion nociceptor current signature |
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