Medical Research Society
7~by decay analysis, and by counting on y and fi detecting devices.The fluxes over the Garious periods during the experiment are calculated from this data. Fluxes were measured under both 'open' and 'short circuit' conditions, and were all in the range 0-150 ,uEq/cm2/min, whilst the S.C.C. was about 5-10 ,uEq/cm2/min. The effects of ADH (10-lO~) and DNP (10--5~) on the four fluxes were unable to be detected in these preliminary experiments owing to the design of the apparatus.Neutron activation was performed in conjunction with Mr M. Kerridge at the University of London Reactor, Ascot, Berks.
To test the applicability of Gibbs-Donnan diffusion equilibrium formulae to ultrafiltration, we have examined sodium (Na) and chloride (Cl) concentrations in ultrafiltrates collected directly from cellophane and cuprophane coils perfused with albumin-electrolyte solutions in a closed reservoir system. The ratio of ultrafiltrate to perfusate water Na concentration (UF/P Na) and the similar ratio UF/P Cl were 1.0 when albumin concentration was zero. UF/P Na decreased and UF/P Cl increased as albumin concentration was increased and pH maintained at 8.0–8.4. By linear regression, UF/P Cl = 0.017 [albumin (g/l00 ml)] +0.97 and UF/P Na = 0.99–0.011 [albumin]. With a nearly constant circulating albumin concentration (7.4–8.5 g/l00 ml) UF/P Na increased curvilinearly from 0.85 to 1.2 as circulating pH was decreased from 8.7. to 1.8 with HCl, and approached 1.0 near the isoelectric point of albumin (pH = 4.2). Simultaneously UF/P Cl decreased from 1.05 to 0.66 in a similar manner and approached 1.0 at a pH near 7.2. In all studies, measured UF/P Cl was usually less than the reciprocal of UF/P Na. Neither ultrafiltration rate nor the type of membrane used altered UF/P values. We conclude: 1. Protein charge does influence UF Na and Cl concentrations in directions predicted by formulae applicable to diffusion equilibrium; 2. Deviations of UF/P Cl from Gibbs-Donnan and isoelectric predictions are compatible with albumin chloride binding as reported in diffusion studies; 3. The electrolyte composition of filtrates from capillary beds such as glomeruli might be predicted to demonstrate similar deviations from Gibbs-Donnan formulae.
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