Total nondialyzable solids (TNDS) in human urine. V. Subfractionation of the ultrafiltrate (UF-O) fraction.

A procedure has been reported (1) for the reproducible separation of the total nondialyzable solids (TNDS) of normal human urine into three primary fractions. The most abundant of the-three fractions, designated UF-O, was separated from the other two by virtue of its passage through a collodion ultrafilter membrane. The overall chemical composition of fraction UF-O was described , but no further information was then available. Accordinigly, we have devised a procedure for the separation of this material into subfrac-tions. While these subfractions appear to be cleanly separated, they are all probably mixtures of various chemical compounds. The method yields consistent results and therefore seems to be a useful tool for the study of possible changes in physiological and pathological conditions, and as an intermediate step in the ultimate separation of the components of UF-O. This report describes the procedure for the subfractionation of the UF-O and the results obtained with it, including the range of normal daily variation in the excretion of the subfractions and their overall chemical composition. Some pertinent ancillary information about the TNDS, acquired during these experiments, is also included. MATERIALS AND METHODS Subjects. Three 24 hour urine specimens were collected , with chloroform preservative, by each of 12 normally active, healthy subjects (eight male, four female). With one exception, they were the same subjects as in preceding reports of this series (1-3). Two male subjects were Negroes. The collections were made during the period September 15 to December 10. As each day's specimen was completed, the process of dialysis and subsequent fractionation of the TNDS was begun, as previously described (1, 2). Fractionation procedure. The subfractionation procedure for fraction UF-O depends essentially on three ob-* Supported by Mary Reynolds Babcock Foundation and Public Health Service Grant A-259. servations. First, it had been noted (1) that the process of lyophilization effected a change in UF-O, manifested by the conversion of a large proportion of it to a dialyz-able form. Preliminary experiments indicated that this was not the result of a purely random breakdown; instead , it seemed to be confined to some particular part of the UF-O. A further experiment showed that the lyophilization process alone, and not the fractionation per se, was responsible for this dialyzability, since concentration of UF-O by rotary evaporation did not cause any portion of it to become dialyzable. The second observation was that, of the portion which did not become dialyzable …