Warm cells revealed by microfluorimetry of Ca2+ in cultured dorsal root ganglion neurons

Warm cells were identified by Fura-PES-based microfluorimetry of Ca2+ in cultured dorsal root ganglion (DRG) neurons. In response to a physiologically relevant stimulus temperature (43 degrees C), a subpopulation of small DRG neurons from new born rats increased the intracellular Ca2+ concentration ([Ca2+](i)). Seven percent of the cells responded to the warm stimulus. The stimulus evoked elevation in [Ca2+](i) from 52.5 +/- 9.5 nM (mean +/- S.D., n = 18) to 171.0 +/- 15.6 nM in cells between 15 and 25 mu m in diameter. The depletion of extracellular Ca2+ diminished the Ca2+ elevation. The Naf-free condition also diminished the response. We concluded that the heat stimulation opens nonselective cation channels in putative warm cells from DRG neurons. (C) 1998 Elsevier Science B.V. All rights reserved.