Previous studies have shown that organic anions can be used to demonstrate active accumulation in certain tissues; thus, phenol red was reported to be concentrated within the lumina of isolated frog and flounder renal tubules (Foster, '48; Foster and Taggart, '50) and the mesonephros of the chick embryo (Chambers and Kempton, '33). Phenol red was also used to demonstrate the secretory activity of the chorioid plexus of chick, rat, and rabbit embryos and of three-day-old hatched chicks (Cameron, '53). These studies revealed that the process of active dye accumulation against a concentration gradient was one which required the expenditure of energy and that the concentrating ability could be inhibited by cold, anoxia and metabolic inhibitors.Friedenwald and Stiehler ('38) demonstrated an irreciprocal permeability in the rabbit ciliary body to certain dystuffs. Acid dyes when introduced on the stromal side of the ciliary body filled the stroma and did not penetrate the epithelium, whereas when the dyes were placed on the epithelial side they penetrated into the stroma. The accumulation was blocked by anoxia and cyanide (Friedenwald and Stiehler, '38).Becker recently demonstrated that the organic anion, iodopyracet (Diodrast ) labeled with F, was accumulated by preparations of rabbit ciliary body and iris in vitro. Saturation kinetics could be demonstrated and the concentrating mechanism could be inhibited by metabolic and competitive inhibitors as well as by lowered temperature and the lack of glucose, oxygen or potassium in the incubation media (Becker, '60).Chlorphenol red was found to be transported in a similar manner to phenol red by the flounder renal tubules (Foster and Hong, '58). The bluish red color of chlorphenol red was more readily perceived and this color was stable within the pH range of tissue maintenance. Because of these advantages over phenol red, this dye was selected for use in the present investigation.
METHODAlbino rabbits weighing approximately 2.0 kg were sacrificed by air embolism. Their eyes were promptly enucleated and placed in staining dishes containing Tyrode's solution. The eyes were opened posteriorly and the lens and vitreous were dissected free. The ciliary body and iris were removed as a complete ring and placed in another staining dish with Tyrode's solution. The iris was then carefully dissected free leaving the ciliary processes easily visible. The ring of ciliary body was divided into approximately 7 equal pieces. Each piece was placed on a 22-mm cover slip with a drop of Tyrode's solution from a 22-gauge syringe needle. The round cover slip was attached by a drop of Tyrode's solution to a heavier glass slide which was then inverted and placed over Maximow-type culture slides.In this investigation a total of 373 preparations were observed. Incubations were carried out at 27°C and the slides were observed under a microscope at various time intervals. It was found that two hours of incubation was sufficient for maximum accumulation and for a comparison of the
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