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B. Tockner, B. Bogner, C. Runge, G. Grabner, K. Weikinger, H. A. Reitsamer; Different Modulation of Blood Flow Regulation in the Ciliary Body and the Choroid With Adenosine. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2283.
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To investigate the effect of intravenous adenosine on choroidal and ciliary blood flow regulation
In anesthetized New Zealand rabbits (n=12) 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. Laser Doppler flowmetry was used to measure choroidal blood flow (ChorBF) and ciliary blood flow (CilBF) continuously. A novelty of the blood flow measurement technique presented in this study is the simultaneous measurements of ciliary and choroidal blood flow in the same animal while MAP was manipulated mechanically with occluders placed around the aorta and vena cava, thus changing ocular perfusion pressure (PP) over a wide range. Pressure-flow (PF) relationships were measured at control and in response to adenosine (5 mg/kg/h infusion rate).
Adenosine caused a significant upward shift of the choroidal pressure flow relationship whereas the ciliary pressure flow relationship did not change at all. While intraocular pressure and orbital venous pressure increased in this short time measurement, choroidal vascular resistance, perfusion pressure decreased. The baseline results are summarized in the table.Table. Baseline effects of adenosine.
Adenosine is a vasodilator in the choroidal vascular bed whereas it has no effect on ciliary blood flow regulation. Furthermore adenosine increases IOP and OVP.
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