Ureteral action potential and histological changes in the upper urinary tract receiving the formalin

The present study investigates the ureteral action potential and histological changes of pelvi-ureteral system after injection of the formalin into the obstracted ureters or the renal pelvis. In the first experiment, formalin was injected into the obstructed ureters of 18 dogs for 30 minutes. In the second, formalin was injected into the obstracted renal pelvis of 13 dogs for 30 minutes using ureteral balloon catheters, and then renal pelvis were released from obstraction and catheters were removed. In these experiments, ureteral electromyogram were recorded and histological changes of pelvi-ureteral system were also observed microscopically. Results 1. After injection of formalin into the ureters, ureteral action potential disappeared and had not restored. Histologically, damage was observed in the ureteral smooth muscle as well as in the mucosa. 2. After injection of formalin into the renal pelvis, ureteral action potential disappeared in 46% of the ureters. In 54% of the ureters, action potential had not disappeared, however discharge interval became irregular. Histological changes of the renal pelvis was not related to the presence or absence of ureteral action potential. The results of the present study show that ureteral smooth muscle play part in the conduction of the ureteral excitation, and have an irregular autonomic discharge.