IMPORTANCE OF CONTRACTILE PROTEIN MEASUREMENT IN THE DILATED URETER

Abstract

Using an SDS-polyacrylamide gel electrophoresis, the contractile protein contents were examined in the animal model of dilated ureter and human dilated ureters. In the animal model, the amounts of contractile proteins were measured in both the ureteral tissue and the ureteral muscle coat. In the tissue the myosin and actin contents were inconsistent with histological findings of the rabbit dilated ureters. Compared with the rabbit normal ureters, the contractile protein contents of the muscle coat showed no change in the dilated ureters. These findings were consistent with the results that in the dilated ureters the maximum active stress per muscle unit area was the same as that in the normal ureters.
Based on these results obtained from the animal experiments, the contractile protein contents of the human ureters were examined only in the muscle coat. In 12 human normal ureters, the amounts of the contractile proteins were fairly constant (myosin: 6.33±1.07mg/g, actin: 7.08±1.17mg/g) while in 12 dilated ureters they showed a great variation. Based on the actomyosin content (myosin plus actin contents), all dilated ureters could be classified into the three groups: the high, normal and low content groups. The histological finding of the high content group showed muscle hypertrophy. This group also showed a significant increase in both the myosin and actin contents per one smooth muscle cell, indicating an increase in the contractile strength of the dilated ureter. In the low content group, muscle atrophy was observed histologically and the cellular amounts of contractile proteins were significantly decreased, suggesting a complete loss of ureteral contractility. Regarding the normal content group, the cellular contractile protein contents were almost the same as the normal ureter. Although cellular ability to contract was not so impaired in this group, the contractility of the whole ureter seemed to be decreased because collagen proliferation was observed around muscle cells.
It seems from these results that the contractile protein measurement is a usefull method for predicting the contractility of the dilated ureter.