Adenosine agonist regulation of outward active transport of fluorescein across retinal pigment epithelium in rabbits

Abstract To investigate the effect of an adenosine agonist, 2-5′- N -ethylcarboxamidoadenosine (NECA), on the outward active transport of fluorescein across the retinal pigment epithelium (RPE) in rabbits. High (5×10 −4 –2×10 −3 m ) and low (1×10 −5 –1×10 −4 m ) concentrations of NECA or phosphate buffered saline (PBS) were intravitreously injected into Dutch-belted rabbits. Sodium fluorescein was injected intravenously 180 min after NECA. Differential vitreous fluorophotometry was performed 3 hr after the sodium fluorescein injection and the vitreal fluorescein/fluorescein monoglucuronide (F/FG) ratio then was calculated. The F/FG ratios are inversely proportional to the outward active transport of fluorescein across the RPE. Retinal detachments were induced by injection of PBS into the subretinal space after the intravitreous injection of low- or high-dose NECA or PBS, and the size of the blebs was monitored. In eyes that received a low-dose injection of NECA, the F/FG ratio was higher compared with controls ( P P P