Purpose:
To investigate the dose dependency of intravenous adenosine on choroidal and ciliary blood flow regulation.
Methods:
In anesthetized New Zealand rabbits (n=19) 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 and simultaneously 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. The aim of this protocol was to compare the choroidal and ciliary pressure-flow relationship under control and in response to intravenous infusion of adenosine at 2.5, 5, 10, 20 and 30 mg/kg/h.
Results:
See table for baseline values.
Conclusions:
Adenosine caused a dose dependent decrease of choroidal and ciliary vascular resistance, however, the effect was more pronounced in the choroidal than in the ciliary circulation.
Keywords: adenosine • blood supply • drug toxicity/drug effects