[Ureteral function at the ureterovesical junction. Action potentials of the canine intramural ureter during bladder...

The relationship between bladder movements and the intramural ureter was studied in the dog by recording electromyograms of the intramural and extravesical ureters recorded during bladder filling and contraction. Bladder filling was achieved by instilling physiological saline at a rate of 10 ml/min to a volume of 5 ml/kg, while bladder contraction was induced by electrical stimulation. For electromyography, an electrode was inserted transperitoneal into both the extravesical ureter and the intramural ureter after it had been separated from the extravesical ureter. A cystostomy for the instillation of water and another cystostomy for the measurement of intravesical pressure were also made in the bladder. During bladder filling at an intravesical pressure of about 10 cmH2O, the frequency of the action potentials in the intramural ureter showed no significant difference to those in the extravesical ureter. In addition, during bladder contraction at a greatly increased intravesical pressure of about 5 times the precontraction level, the frequency of the action potentials in the intramural ureter was not significant by different from those in the extravesical ureter, and also from its own precontraction value. The above findings suggest that action potentials in the intramural ureter are not affected by bladder movements such as filling or contraction, and that the ureter continues to actively transport urine to the bladder during such movements.