Quantitative immunological determination of 12 plasma proteins excreted in human urine collected before and after exercise

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Abstract
Urine was collected from 6 healthy male adults at rest and from 20 male adults after a marathon race (25 miles). The concentrated urines were quantitatively analyzed, by single radial immunodiffusion, for their content in 12 different plasma proteins: tryptophan-rich prealbumin, albumin, α1-acid glycoprotein, α1-antitrypsin, ceruloplasmin, haptoglobin, Gc-globulin, transferrin, hemopexin, β2-glycoprotein I, γA-globulin, and γG-globulin. Albumin, γA-globulin, and γG-globulin represent the major part of the plasma proteins detected in normal urine excreted by humans at rest (12, 0.5, and 2.5 mg respectively, out of a total excretion of 17.5 mg of plasma proteins per 24 hr). The other plasma proteins were excreted at a lower rate (< 0.4 mg/24 hr). The relative content of tryptophan-rich prealbumin, α1-antitrypsin, Gc-globulin, transferrin, and γG-globulin was lower in normal urine than in normal serum, whereas that of α1-acid glycoprotein, β2-glycoprotein I, and γA-globulin was higher. The ratio of γG-globulin to γA-globulin was 4.9:1. When plotted on a logarithmic scale, no direct relationship between the molecular weight of a protein and the value of its renal clearance could be observed. Strenuous exercise increased (up to 50-fold) the excretion of plasma proteins which represent 82% of the total proteins found in urine, instead of 57% in urine collected from humans at rest. There was particularly a significant rise of tryptophan-rich albumin, albumin, α1-acid glycoprotein, transferrin, γA-globulin, and γG-globulin (0.26, 127, 11.8, 3.3, 1.2, and 2.0 μg respectively, out of a total excretion of 167 μg of plasma proteins per min). The ratio of γG-globulin to γA-globulin was 16:1. After exercise, the renal clearance of proteins increased from 2 to 40 times, but, as for the urine of normal subjects at rest, no direct relationship between molecular weight and renal clearance could be observed.

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