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C. Runge, H. Brandtner, B. Bogner, C. Strohmaier, F. Schrödl, G. Grabner, H. A. Reitsamer; The Role of VIP on Choroidal Blood Flow Regulation. Invest. Ophthalmol. Vis. Sci. 2010;51(13):2694.
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To investigate the effect of VIP and its antagonist VIP (6-28) on the choroidal choroidal blood flow regulation in rabbits.
In anesthetized New Zealand white rabbits (n=10) the mean arterial pressure (MAP)and intraocular pressure (IOP) were measured by direct cannulation of the central ear artery, and the vitreous, respectively. Laser Doppler flowmetry was used to measure choroidal blood flow (ChorBF) and choroidal vascular resistance (ChorR). VIP infusion was administrated intravenously (20 ng/kg/min), the antagonists, VIP (6-28) was given as a bolus (80 ng/kg).
See table 1. The increase of ChorBF and the decrease of ChorR in response to VIP infusion were significant. The effect of the VIP receptor blocker VIP(6-28 ) on both variables was also significant as it was on the reduction of IOP. However, higher infusion rates of VIP were not completely blocked by the VIP receptor antqagonist, indicating a different mechanism involved in the vasodilaotry reponse to this neuropeptide or insufficient blockage by the antagonist.
VIP is a highly potent vasodilatator in the choroidal vascular bed. The effect was blocked by its antagonists VIP (6-28). VIP also caused a significant upward shift of the choroidal pressure-flow relationship.
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