[Ureteral compliance of dilated ureters in dogs]

Compliance and histological findings of dilated ureters in dogs were successively examined after partial ligature. Ureteral compliance was measured by the impedance method using a special probe. This probe, with a balloon at the tip, is equipped with two detecting electrodes and two generating electrodes. Adult mongrel dogs were anesthetized with pentobarbital, and the lower part of the extravesical ureter was partially ligated. At 1, 2, 4, 8, 12, and 26 weeks after ligature, ureteral compliance and histological findings were investigated. Moreover, the closure pressure and the initial cross sectional area of the dilated ureter were measured. The results of the study were as follows: 1) In the dilated ureter, compliance increased gradually for 8 weeks after ligature. However, compliance began to decrease at 12 weeks. 2) The ureteral closure pressure of the normal ureter was statistically higher than that of the dilated ureter. 3) The initial cross sectional area of the normal ureter was statistically lower than that of the dilated ureter. 4) Hypertrophy and hyperplasia of the muscle bundles were found in the dilated ureteral wall. 5) The stellate configuration of the ureteral epithelium almost disappeared 8 weeks after ligature. 6) The proliferation of connective tissues around the muscle bundles were observed 8 weeks after ligature. 7) Ureteral compliance increased in proportion to hypertrophy of the muscle. However, compliance decreased with the increase of the proliferation of connective tissues. These results indicated that the decrease in compliance caused by the proliferation of the connective tissues was one of the reasons for dysfunction of urine transport in the dilated ureter.(ABSTRACT TRUNCATED AT 250 WORDS)