Electro-ureterogram: canine study of the electromechanical activity of the ureter

The purpose of this investigation was to study the electromechanical activity of the ureter aiming at characterizing an "electro-ureterogram" that might be of diagnostic significance. Eighteen mongrel dogs were used in this study. Under anesthesia the ureter was exposed and three electrodes (monopolar, silver-silver chloride, 0.8 mm in diameter) were sutured to the ureteric adventitia, 2-3 cm apart. The intraureteric pressure was measured by a scalp vein needle inserted into the ureteric lumen and connected to a pressure transducer. The ureteric electric activity and pressure were recorded 30 min daily for 15 days. The electric activity was also registered after having performed ureteric myotomy in 12 out of 18 dogs. Monophasic negatively deflected slow waves or pacesetter potentials were recorded. Their frequency, amplitude, and velocity were identical in the three electrodes and reproducible. The pacesetter potentials were followed by fast activity spikes or action potentials that occurred randomly and were inconsistent. The action potentials were associated with ureteric pressure increase. After ureteric myotomy, both the pacesetter potentials and action potentials were recorded proximally to the myotomy but not distally to it, indicating a caudal spread of the waves. In conclusion, a normal electro-ureterogram could be characterized. It might show changes in various pathologic conditions of the ureter and could thus be included as an investigative tool in the diagnosis of ureteric diseases.