Study of the electromechanical activity of the urinary bladder. An experimental study.

The electromechanical activity of the urinary bladder (UB) was studied in 16 dogs. With the animals under anesthesia, the UB was exposed and four electrodes were sutured serially to its anterior wall. Electric activity simultaneously with vesical pressure was recorded for periods of 30 min daily on 10 days. Triphasic pacesetter potentials (PP) were registered from electrodes 1-4, having identical frequency and regular rhythm by all electrodes and being consistent in the individual dog on all test days. Action potentials (AP) followed PP randomly and were accompanied by vesical pressure increase; they represented vesical contractile waves. Balloon distension of the UB effected increased PP and AP frequency. Annular vesical myotomy led to PP and AP disappearance distal but not proximal to the myotomy, which would suggest that (a) the waves spread caudally and (b) a "pacemaker" exists at the upper part of the UB and triggers the PP.