NGF administered by microdialysis into rabbit vitreous

Purpose: Microdialysis has been used in eye research for almost a decade, W e have previously developed and used it mainly for chronic experiments and here it is used in acute experiments. It is highly suitable for both admini stration and withdrawal of substances from the eye, as it only permits mole cules to cross the intraocular membrane without any net fluid movement in o r out of the eye. Methods: We have here investigated the ability of I-125 labeled NGF (nerve growth factor) to cross a previously implanted high permeability membrane o f a new type (polyether sulphone, PES, cutoff at 100 000 daltons) in the ra bbit vitreous. It was perfused for different time periods with a solution c ontaining NGF, The radioactivity of the entire vitreous was then counted, Results: The results show detectable levels (up to 10(-11)M) of the substan ce after the perfusions. Conclusion: We conclude that microdialysis with PES membranes is a possible method for the intraocular administration of NGF.