Merkel Cells Release Glutamate Following Mechanical Stimulation: Implication of Glutamate in the Merkel Cell-Neurite Complex.

Merkel cells (MCs) have been proposed to form a part of the MC-neurite complex with sensory neurons through synaptic contact. However, the detailed mechanisms for intercellular communication between MCs and neurons have yet to be clarified. The present study examined the increases in intracellular free Ca concentration ([Ca]) induced by direct mechanical stimulation of MCs.

Intracellular Ca mobilization pathway via bradykinin B receptor activation in rat trigeminal ganglion neurons.

Bradykinin (BK) and its receptors, B and B, in trigeminal ganglion (TG) neurons are involved in the regulation of pain. Recent studies have revealed that B receptors are expressed in neonatal rat TG neurons; however, the intracellular signaling pathway following B receptor activation remains to be elucidated. To investigate the mechanism by which B receptor activation leads to intracellular Ca mobilization, we measured the intracellular free Ca concentration ([Ca]) in primary-cultured TG neurons.

High pH-Sensitive Store-Operated Ca Entry Mediated by Ca Release-Activated Ca Channels in Rat Odontoblasts.

Odontoblasts play a crucial role in dentin formation and sensory transduction following the application of stimuli to the dentin surface. Various exogenous and endogenous stimuli elicit an increase in the intracellular free calcium concentration ([Ca]) in odontoblasts, which is mediated by Ca release from intracellular Ca stores and/or Ca influx from the extracellular medium. In a previous study, we demonstrated that the depletion of Ca stores in odontoblasts activated store-operated Ca entry (SOCE), a Ca influx pathway.

Potassium Currents Activated by Depolarization in Odontoblasts.

Increased intracellular free Ca concentrations elicit plasma membrane depolarization, which leads to the activation of K currents. However, the precise properties of K currents activated by depolarization in odontoblasts remain to be elucidated. The present study identified biophysical and pharmacological characteristics of time-dependent and voltage-activated K currents in freshly dissociated rat odontoblasts using patch-clamp recordings in a whole-cell configuration.

Transient Receptor Potential Cation Channel Subfamily Vanilloid Member 3 is not Involved in Plasma Membrane Stretch-induced Intracellular Calcium Signaling in Merkel Cells.

Merkel cells (MCs), which form part of the MC-neurite complex, making contact with sensory afferents to drive mechanosensory transduction mechanisms, express transient receptor potential (TRP) cation channel subfamily vanilloid (V) members 1, 2, and 4, as well as ankyrin subfamily member 1. While these proteins are involved in sensing plasma membrane stretch, less is known about the functional properties of TRPV subfamily member 3 (TRPV3) during membrane stretch in MCs. The aim of this study was to determine whether TRPV3 channels were involved in mechanosensory activity by measuring intracellular free Ca(2+) concentrations ([Ca(2+)]i) in MCs isolated from hamster buccal mucosa.

Depolarization-induced Intracellular Free Calcium Concentration Increases Show No Desensitizing Effect in Rat Odontoblasts.

Odontoblasts play an important role in the transduction of the sensory signals underlying dentinal pain. Transmembrane voltage-independent Ca(2+) influx in odontoblasts has been well described. Voltage-dependent Ca(2+) influx has also been reported, but its biophysical properties remain unclear.