Pulsed Infrared-evoked Intracellular Calcium Transients in Neonatal Vestibular and Spiral Ganglion Neurons

Pulsed infrared radiation (IR) has been shown to have high spatial selectivity and could potentially be used in auditory and vestibular prostheses. Results from stimulation of cardiomyocytes suggest that pulsed IR evokes intracellular Ca2+ responses. In the present study, we analyzed the response of rat neonatal vestibular and spiral ganglion neurons to infrared radiation (IR), ? = 1863 nm, in vitro. Both types of neurons responded with intracellular [Ca2+]i transients that could be entrained by the low frequency IR pulses (0.25-5 pulses/s). When challenged with an inhibitor of the mitochondrial Na+/Ca2+ exchanger (CGP-37157) and a blocker of mitochondrial Ca2+ uniporter (Ruthenium Red), the IR-evoked responses were blocked or significantly reduced. This suggest that mitochondrial [Ca2+]i flux may be a primary source of the IR transients.