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This Article Full Text Full Text (PDF) All Versions of this Article: 584/2/535    most recent jphysiol.2007.139675v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Nouvian, R. Search for Related Content PubMed PubMed Citation Articles by Nouvian, R. Related Collections Neuroscience

¹ InnerEarLab, Department of Otolaryngology, Center for Molecular Physiology of the Brain, Bernstein Center for Computational Neuroscience, Göttingen University Medical School, Robert-Koch-Strasse 40, 37075 Göttingen, Germany

Hearing relies on fast and sustained neurotransmitter release from inner hair cells (IHCs) onto the afferent auditory nerve fibres. The temperature dependence of Ca²⁺ current and transmitter release at the IHCs ribbon synapse has not been investigated thus far. To assess the influence of temperature on calcium-triggered exocytosis, patch-clamp recordings of voltage-gated L-type Ca²⁺ influx and exocytic membrane capacitance changes were performed at room (25°C) and physiological (35–37°C) temperatures. An increase in temperature within this range increased the L-type Ca²⁺ current amplitude of IHCs (Q₁₀ = 1.3) and accelerates the activation kinetics. Fast exocytosis, probed by 20 ms depolarization, was enhanced at physiological temperature with a Q₁₀ of 2.1. The amplitude of fast release was elevated disproportionately to the increase in Ca²⁺ influx. In contrast, the rate of sustained exocytosis (exocytic rate between 20 and 100 ms of depolarization) did not show a significant increase at physiological temperature. Altogether, these data indicate that the efficiency of fast exocytosis is higher at physiological temperature than at room temperature and suggest that the number of readily releasable vesicles available at the active zone is higher at physiological temperature.

(Received 27 June 2007; accepted after revision 21 August 2007; first published online 23 August 2007)
Corresponding author R. Nouvian: Department of Otolaryngology, Göttingen University Medical School, Robert-Koch-Strasse 40, 37075 Göttingen, Germany. Email: nouvian{at}med.uni-goettingen.de

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