Tamm-Horsfall (T-H) glycoprotein was demonstrated in the developing hamster kidney using immunofluorescence and immunoelectron microscopical techniques. The glycoprotein was first observed in the fetal kidneys on the 12th day of gestation and was confined to the luminal surface of the presumed distal tubules of the medulla. It was not until the 14th day of gestation that T-H glycoprotein was also sometimes seen to be associated with the lateral and basal invaginations of the plasma membranes of the now differentiated distal tubules. On the 16th day (1st day post-partum) the glycoprotein was also found in the cortex. Although the general distribution of T-H gylocoprotein was at 3–4 days after birth similar to the adult, the full intensity of staining was not attained until after the 21st day. The possible physiological significance of these findings is discussed.
1. Tamm-Horsfall glycoprotein was determined, by radioimmunoassay, in samples of urine from normal individuals under a variety of physiological conditions. 2. The amount of glycoprotein excreted in 24 h by our population (39 +/- 13 mg, corrected for body surface area) was found not to be influenced by sex, age (19-60 years) or amounts of Ca2+, Mg2+ and Na+ excreted. 3. Urine samples collected at 2 h intervals over 24 h from individuals drinking in response to thirst, contained quantities of the glycoprotein which showed high positive correlations with urine volumes, but not with Ca2+, Mg2+ or Na+ excretion. 4. The amounts of urine and of the glycoprotein were correlated for individuals in antidiuresis, induced by restriction of water intake. Relatively small amounts of glycoprotein were excreted by individuals in states of water-induced diuresis. 5. The amounts of glycoprotein excreted after exercise were positively correlated with the small volumes of urine voided, but they were uninfluenced by the degree of proteinuria or of hyaline cast formation. 6. The half-life for turnover of the glycoprotein in a given individual is highly variable, from a minimum of 3-7 to a maximum of 168 h.
Freeze-drying or freezing of salt-free solutions of human Tamm--Horsfall glycoprotein appeared to lead to changes in the structure of the latter, changes that increased its ability to bind with antibody raised, in rabbits, against it. This alteration in avidity of the glycoprotein was observed irrespective of whether antiserum was raised against freeze-dried or non-frozen antigen. The implications of this finding for the radioimmunoassay of the glycoprotein in urine samples were studied. Appropriate treatment for urine samples, before assay, was devised. The amount of Tamm--Horsfall glycoprotein excreted was shown to range from 30 to 138 mg in normal males and 43 to 126 mg in normal females per 24 h.
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