Studies on the physiological and pharmacological aspects of the lower urinary tract in normal and following spinal lesion

Abstract

The mechanisms implicated in voiding and continence are far from being settled in the normal as well as in neurogenic bladder dysfunction. Understanding these mechanisms is an essential step in the management of the bladder dysfunction secondary to neurological lesions. In the course of our studies, we demonstrated the existence of a fine coordination "synergism" between the several components of the lower urinary tract i.e., detrusor, proximal urethral muscle and periurethral striated muscles. This synergism is found to be responsible for adequate bladder emptying during voiding in the animal model with intact neural axis. The synergism between the bladder and its outlet is under the control of a higher centre in the brain stem and mediated through the spinal cord and peripheral nerves. The cause of failure of bladder emptying following a spinal lesion was shown to be a lack of synergism between the bladder and its outlet. An animal model for chronic multiple sclerosis-like disease was developed and proved to show a good urodynamic and neurological correlation with that found in the human afflicted with multiple sclerosis.The pharmacological investigation on the bladder and urethra shows that there is selective distribution of cholinergic, adrenergic and purinergic receptors along the individual layers of the smooth muscles of the urethra. On the other hand, the importance of the Calcium ions in the contractility of the detrusor muscle was also studied. The effect of some Calcium ions antagonists on the detrusor contractility was evaluated. They show selective inhibition on the detrusor contraction both in vivo and in vitro. The calcium antagonists may present a new treatment modality for controlling bladder instability