Mechanical stimuli induce intracellular calcium response in a subpopulation of cultured rat sensory neurons

Abstract

Cultured dorsal root ganglion neurons from newborn rats were mechanically deformed with a fine-tipped glass capillary, and the change in the intracellular Ca 2+ concentration ([Ca 2] i) was recorded by Fura-2-based microfluorimetry. The deformation evoked elevation in [Ca 2+] i from 18.7±5.4 nM (mean±S.E.M., n=35) to 137.1±15.2 nM in some subpopulations of cells, especially those larger than 20 μm in diameter. The largest mechanosensitive cell group was that of cells 20–25 μm in diameter; 56% of the mechanosensitive cells were of this cell size. All of the cells larger than 25 μm in diameter displayed the Ca 2+ increase when prodded. The depletion of extracellular Ca 2+ diminished the Ca 2+ elevation. Verapamil and nickel, blockers of voltage-dependent Ca 2+ channels, did not influence the Ca 2+ response, whereas gadolinium, a relatively selective blocker of mechanosensitive channels, diminished the response. Na +-free conditions did not influence the response. We concluded that the mechanical stimulation induced a Ca 2+ influx in large dorsal root ganglion neurons through mechanosensitive Ca 2+-permeable channels.