Vesicourethral electromyography: facts or artefacts

A vesicourethral electromyographic study was carried out on 21 cats of both sexes with extracellular electrodes along with monitoring of contraction and relaxation of various parts of the bladder and urethra. No consistent electromyographic pattern of slow and fast waves was observed in the bladder and urethra either in any empty bladder or during filling and voiding phases. Most of the recorded waves were traced to a defined source of artefact. Twenty-two experiments were done with glass microelectrodes recording intracellularly in bladder strips of various animals bathed in normal and modified Krebs solutions. No spike activity was recorded during periods of contractions, whether spontaneous or electrically stimulated. Both in vivo and in vitro experiments suggest that the mechanism of excitation-contraction coupling of the bladder remains unidentified. The clinical application of bladder electromyography (EMG) has to be interpreted cautiously.