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Jennifer McNaughten, Mary McGahon, Graham McGeown, Timothy Curtis; Functional Expression Of TRPV Channels In The Retinal Endothelium. Invest. Ophthalmol. Vis. Sci. 2013;54(15):6314.
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© ARVO (1962-2015); The Authors (2016-present)
Transient receptor potential vanilloid (TRPV) channels are part of a superfamily of non-selective cation channels with a vast range of physiological functions. Our aim was to identify the functional TRPV channel subtypes expressed in the retinal endothelium.
Retinal microvascular endothelial cells (RMECs) were cultured from bovine arterioles. Fura-2-based Ca2+ microfluorimetry was used to test for the functional expression of TRPV1, V2, V3 and V4 in RMECs using a selection of agonists and antagonists.
The ultrapotent TRPV1 agonist resiniferatoxin(10nM) caused a transient rise in calcium in 50% of cells tested. These responses were abolished in the presence of two different TRPV1 antagonists, capsazepine(5uM) and AMG9810(100nM). Functional expression of TRPV2 was evident from calcium peaks in response to Δ9-THC(10uM). The responses were reduced after incubation with tranilast(75uM), a TRPV2 inhibitor. Carvacrol(100uM) provided evidence for the presence of TRPV3 in RMECs causing consistant calcium responses across a number of cells. Both tranilast and carvacrol were used in the presence of the TRPA1 antagonist HC-030031(10uM). The well known TRPV4 channel was tested for using GSKA(100nM) and 4αPDD(1uM). Both elicited transient rises in calcium. The specific TRPV4 antagonist HC067047(1uM) blocks responses caused by GSKA. The aforementioned TRP channels were tested for in EGTA(1mM) buffered calcium free solution. Under these conditions none of the agonists initiated a rise in calcium suggesting the responses were mediated by calcium influx from the extracellular medium.
This study provides evidence for the functional expression of TRPV1-V4. This warrants further research to elucidate the physiological significance of TRP channels in endothelial cell function.
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