A Method to Determine Osmotically Effective Albumin and Gammaglobulin Concentrations in Tissue Fluids, Its Application to the Uvea and a Note on the Effects of Capillary “Leaks” on Tissue Fluid Dynamics

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Abstract
Choroids and ciliary processes from rabbits were incubated with labelled myoglobin, albumin and gammaglobulin and the equilibrium spaces were determined. Using experimental data for the in vivo steady state myoglobin space in each tissue an approximate value for the in vivo equilibrium space could be calculated. The in vivo albumin and gammaglobulin equilibrium spaces were calculated using the data for in vivo equilibrium myoglobin spaces and the differences in spaces determined in vitro. Values for the effective albumin and gammaglobulin concentrations in the tissues were calculated by dividing the in vivo steady state spaces by the calculated in vivo equilibrium spaces. In the choroid the effective albumin and gammaglobulin concentrations were 68 and 48 per cent of those in plasma respectively. In the ciliary processes the corresponding figures were 74 and 67 per cent.Model experiments showed that in membranes with 500 Å pores the apparent colloid osmotic pressure of rabbit plasma, 3 % albumin and 3 % gammaglobulin is less than 1 cm H2O.The results indicate that in the choroid and the ciliary processes there is a net outflow of water in the semipermeable parts of the blood vessels having a transmural hydrostatic pressure difference of more than 7 mmHg. In pores permitting protein passage still less is required to give net outward filtration.