The Albumin Exchange in the Rabbit Eye

Red cells labelled with Cr 51 and albumin labelled with I 131 were given i. v. to unanesthetized rabbits. Additional doses of I 131 ‐albumin kept the plasma concentration of labelled albumin at a steady value. At different times after the first injection the animals were killed and the eyes dissected. The red cell contents of the choroid, the anterior uvea and the retina were the same at all time intervals, while the apparent volume of the plasma equivalent albumin space in the tissues increased with time. The results were analyzed in terms of intravascular and extravascular albumin compartments having the same concentration of I 131 ‐albumin as plasma. The apparent volumes of the extravascular plasma albumin compartments were: in the choroid 112 μ l per g tissue, in the anterior uvea 94 μ l per g tissue and in the retina 4.8 μ l per g tissue. The apparent turnover rates for the albumin solution in the extravascular albumin compartments were: in the choroid 0.0847 μ l per min, in the anterior uvea 0.234 μ l per min and in the retina 0.0075 μ l per min. It was calculated that the albumin concentration in the tissue fluid of the choroid and in that of the anterior uvea as a whole is more than tenfold the albumin concentration in the aqueous humour and that the albumin drainage with the aqueous humour can account for less than 10 per cent of the albumin drainage from the eye.