Betahistine exerts a dose-dependent effect on cochlear stria vascularis blood flow in guinea pigs in vivo.

Objective: Betahistine is a histamine H(1)-receptor agonist and H(3)-receptor antagonist that is administered to treat Menière's disease. Despite widespread use, its pharmacological mode of action has not been entirely elucidated. This study investigated the effect of betahistine on guinea pigs at dosages corresponding to clinically used doses for cochlear microcirculation.

Measurements of membrane patch capacitance using a software-based lock-in system.

On-cell patch-clamp capacitance measurements can resolve the fusion of individual vesicles to a membrane patch and the accompanying dilation of the fusion pore. So far, these measurements have used a patch-clamp amplifier in combination with a hardware lock-in amplifier. Usually, solely the capacitance and conductance outputs of hardware lock-in amplifiers were recorded, which needed to be filtered rather heavily to suppress spectral components at the stimulus frequency.

Structure and function of the hair cell ribbon synapse.

Faithful information transfer at the hair cell afferent synapse requires synaptic transmission to be both reliable and temporally precise. The release of neurotransmitter must exhibit both rapid on and off kinetics to accurately follow acoustic stimuli with a periodicity of 1 ms or less. To ensure such remarkable temporal fidelity, the cochlear hair cell afferent synapse undoubtedly relies on unique cellular and molecular specializations.

Few CaV1.3 channels regulate the exocytosis of a synaptic vesicle at the hair cell ribbon synapse.

Hearing relies on faithful sound coding at hair cell ribbon synapses, which use Ca2+-triggered glutamate release to signal with submillisecond precision. Here, we investigated stimulus-secretion coupling at mammalian inner hair cell (IHC) synapses to explore the mechanisms underlying this high temporal fidelity. Using nonstationary fluctuation analysis on Ca2+ tail currents, we estimate that IHCs contain approximately 1700 Ca2+ channels, mainly of CaV1.

CaV1.3 channels are essential for development and presynaptic activity of cochlear inner hair cells.

Cochlear inner hair cells (IHCs) release neurotransmitter onto afferent auditory nerve fibers in response to sound stimulation. During early development, afferent synaptic transmission is triggered by spontaneous Ca2+ spikes of IHCs, which are under efferent cholinergic control. Around the onset of hearing, large-conductance Ca2+-activated K+ channels are acquired, and Ca2+ spikes as well as the cholinergic innervation are lost.