The detrusor electromyogram and purinergic mechanisms in the bladders of guinea-pig and man
It has been said that a technique capable of recording a urinary bladder electromyogram could be useful in the clinical evaluation of the detrusor neuropathies and myopathies implicated in the generation of lower urinary tract symptoms. However, in contrast to electromyography of skeletal and cardiac muscle, detrusor smooth muscle electromyography has remained in its infancy despite fifty years of scientific effort. The principal problems appear to be isolation of the real signal from artifacts, and uncertainties surrounding the existence of electromyographic activity during parasympathetically mediated muscle contraction. The discovery of purinergic neuromuscular transmission in overactive human bladder samples has renewed interest in detrusor electromyography as, in contrast to cholinergic mechanisms, purinergically mediated contractions can generate extracellular electrical activity. This thesis describes the development and validation of a novel technique for recording electrical activity from neurologically intact guinea-pig bladders and human detrusor in vitro. We characterise a purinergic electromyographic signal and show that detrusor taken from overactive human bladders has a greater propensity to generate electromyographic activity than normal by virtue of an aberrant purinergic mechanism. We discuss the potential role of electromyography in the clinical evaluation of a putative purinergic detrusor myopathy.