The relationship between urinary Tamm-Horsfall glycoprotein excretion and urinary activity of glycosidases in normal pregnancy and pre-eclampsia

Abstract

Electrophoretic analyses of the urinary proteins of pre-eclamptic patients revealed a decrease in the staining intensity of the protein band representing the Tamm-Horsfall glycoprotein (THP). In the present study the quantitative analysis of the THP excretion rate and the urinary activity of THP oligosaccharide metabolizing glycosidases were investigated. The median THP excretion rate of non-pregnant women ( n = 24) was 20 mg/g creatinine (crea.). An increase in the THP excretion rate was seen in pregnancy to a level between 43 mg/g crea. (II. trimester) and 32 mg/g crea. (III. trimester) ( n = 29). Hypertension in pregnancy was associated with a decrease in the THP excretion rate to 9 mg/g crea. ( n = 85). Post partum, a transient elevated THP excretion rate up to 109 mg/g crea was recorded in the group of hypertensive patients. The urinary activities of the lysosomal β-mannosidase, α-fucosidase, α-mannosidase (pH 4.5) and β-galactosidase increased in normal pregnancy. This effect was most pronounced in the β-galactosidase activity which increased from 50 U/mg crea. before pregnancy to 280 U/mg crea. at term. Hypertension in pregnancy was associated with a further increase in the activities of the lysosomal glycosidases. In the case of the β-galactosidase a significant rise from 68 to 310 U/mg crea. was found. The urinary activity of the α-mannosidase (pH 5.5) originating from the Golgi apparatus was only elevated in patients with severe pre-eclampsia. Casuistic post partum recordings demonstrated that an elevation of the lysosomal glycosidases activities was followed by a transient increase in the THP excretion rate.