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B. Bogner, F. Schroedl, C. Runge, C. Strohmaier, G. Grabner, H. A. Reitsamer; Functional Characterization and Localization of Vasopressin Receptor Subtype V1 in the Choroid. Invest. Ophthalmol. Vis. Sci. 2010;51(13):2695.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the physiological role of vasopressin in the choroid and to localize vasopressin receptor subtype V1 in ocular tissues.
In anesthetized New Zealand white rabbits mean arterial pressure (MAP), intraocular pressure (IOP) and orbital venous pressure (OVP) were measured by direct cannulation of the central ear artery, the vitreous, and the orbital venous sinus, respectively. Choroidal blood flow (ChorBF) was measured invasively by Laser Doppler flowmetry at the posterior pole of the eye. To change ocular perfusion pressure (PP) MAP was manipulated by occluders around the aorta and the vena cava. Thus, the effect of exogenous applied arginine-vasopressin (0.08 ng/kg/min and 1.33 ng/kg/min) compared to baseline conditions can be investigated over a wide range of PP. Immunohistochemistry and confocal laser scanning microscopy was applied to localize vasopressin receptor subtype V1 on cryosections of different species (rabbit, human, mouse, rat).
Vasopressin is a potent vasoconstrictor in the choroid at low-dose (p<0.05) and high-dose application (p<0.001). The pressure-flow relationship indicates that during low-dose administration vasoconstriction occurs only at PPs below baseline, however, at high-dose application vasoconstriction was observed over the entire range of PPs. Immunohistochemistry confirmed the presence of vasopressin receptor subtype V1 in the large choroidal vessels and in the choriocapillaris of rabbit and rat. Further testing is required for human and mouse.
The functional study in the rabbit model indicates that the vasoconstrictive effect of vasopressin is not only dose- but also pressure-dependent. The effect is supposed to be receptor-mediated. Immunohistochemistry revealed the presence of vasopressin receptor subtype V1 in the choroidal vascular bed of two different species as anticipated from vasopressin-mediated effects on choroidal blood flow.
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