Browsing by Subject "Calcium channel"

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    Differential expression and localization of transient receptor potential vanilloid 1 in rabbit and human eyes
    (F. Hernández y Juan F. Madrid. Universidad de Murcia. Departamento de Biología Celular e Histología, 2013) Martínez-García, M. Carmen; Martínez, Tamara; Pañeda, Covadonga; Gallego, Patricia; Jimenez, Ana I.; Merayo, Jesus
    Introduction: The superfamily of transient receptor potential (TRP) cation channels is involved in nociception. Members of this family, such as the vanilloid receptor type 1 (TRPV1) channel, are activated by a wide range of stimuli including heat (>43°C), low pH (<6.5), hypoxia, and hypertonicity. Here we report TRPV1 expression in rabbit and human eyes. Material and methods: We analyzed the expression of TRPV1 mRNA by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and protein by immunohistochemistry in eyes of New Zealand White rabbits and humans. Results: In rabbit and human eyes, TRPV1 protein was present in all layers of the corneal epithelium, but only in the basal layer of the conjunctiva. It was also in the ciliary and lens epithelia of both species as well as in the secretory cells of the rabbit lacrimal gland. The retinal pigment epithelium was positive for this protein in both species. TRPV1 was also present in rabbit Müller cells, where it had a similar pattern of expression to vimentin intermediate filaments. Analysis by qRT-PCR showed that TRPV1 mRNA was found in all of the structures where the protein was present. The highest level was in the lens and the lowest in the retina. Conclusion: TRPV1 is expressed in cells that are particularly active in Ca2+ exchange as well as in cells with significant water transport activity. Because TRPV1 is a Ca2+ channel, it probably functions in the regulation of both water and Ca2+ movements in ocular tissues.
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    Localization of the calcium channel subunits Cav1.2 (a1C) and Cav2.3 (a1E) in the mouse organ of Corti
    (Murcia : F. Hernández, 2003) Waka, N.; Knipper, M.; Engel, J.
    Voltage-activated Ca2+ channels play an important role in synaptic transmission, signal processing and development. The immunohistochemical localization of Cav1.2 (a1C) and Cav2.3 (a1E) Ca2+ channels was studied in the developing and adult mouse organ of Corti using subunit-specific antibodies and fluorescent secondary antibodies with cochlear cryosections. Cav1.2 immunoreactivity has been detected from postnatal day 14 (P14) onwards at the synapses between cholinergic medial efferents and outer hair cells as revealed by co-staining with antisynaptophysin and anti-choline acetyltransferase. Most likely the Cav1.2 immunoreactivity was located presynaptically at the site of contact of the efferent bouton with the outer hair cell which suggests a role for class C L-type Ca2+ channels in synaptic transmission of the medial efferent system. The localization of the second Ca2+ channel tested, Cav2.3, showed a pronounced change during cochlear development. From P2 until P10, Cav2.3 immunoreactivity was found in the outer spiral bundle followed by the inner spiral bundle, efferent endings and by medial efferent fibers. Around P14, Cav2.3 immunoreactivity disappeared from these structures and from P19 onwards it was observed in the basal poles of the outer hair cell membranes.