Adrenergic innervation and adrenergic mechanisms. A study of the human urethra

Acquired urinary incontinence in the bitch: update and perspectives from human medicine. Part 2: The urethral component, pathophysiology and medical treatment

Various pathologies can affect the bladder and/or urethral contractility causing signs of urinary incontinence. In this second part of a three-part review, the pathophysiology of impaired urethral contractility (including urethral hyper- and hypotonicity) in the bitch and in women is discussed. Urethral sphincter mechanism incompetence (USMI) is the most common form of acquired urinary incontinence in bitches and is characterized by a decreased urethral tone. The pathophysiology and current recommended medical treatment options for USMI and cases of modified urethral tonicity due to a neurological disorder or functional outlet obstruction are discussed. Treatment options in human medicine in cases of impaired urethral contractility are described.

Contractile responses of rabbit bladder neck to adrenaline, acetylcholine and papaverine after doxazosin treatment

It has been demonstrated that long-term administration of doxazosin, an alpha 1 adrenoceptor antagonist, causes an up-regulation in the expression of alpha 1 adrenoceptor subtype mRNAs in the rat genitourinary tract. The aim of this study is to determine whether this up-regulation does have any effect on contractile response of rabbit bladder neck to adrenaline, acethylcholine and papaverin after long-term doxazosin treatment. Fourteen rabbits, treated with doxazosin 3 mg/kg/day p.o for 6 months, and were fed with a diet of standard laboratory rabbit chow (100 g/kg/day). Ten rabbits received the same amount of regular chow but no drug. Contractile responses of rabbit bladder neck to adrenaline acethylcholine and papaverine were measured.

alpha-Adrenergic blockade in children with neuropathic and nonneuropathic voiding dysfunction

PURPOSE

Inadequate bladder emptying is a common urinary dysfunction in children. The role of alpha-blockers for managing bladder outlet obstruction remains relatively unexplored in children. Because of the well established impact of alpha-blocker therapy in men, we investigated its use for treating inadequate bladder emptying in the pediatric population.

MATERIALS AND METHODS

We treated 17 children 3 to 15 years old with documented poor bladder emptying of various etiologies, including dysfunctional voiding, the Hinman syndrome, the lazy bladder syndrome, posterior urethral valves, myelomeningocele and the prune-belly syndrome, using the alpha-1 adrenergic receptor antagonist, doxazosin. The initial dose of 0.5 to 1.0 mg. nightly was increased according to patient response and as tolerated. Patients were followed weekly to monthly by symptomatic history, and urine flow and/or post-void residual urine volume measurement. Two patients with neurogenic bladder were also followed with cystometrography and leak point pressure determination.

RESULTS

Bladder symptomatology and/or emptying improved in 14 patients (82%). Ten patients had decreased post-void residual urine during treatment and in 3 uroflowmetry showed increased maximum flow. Two patients with neuropathic bladder secondary to myelomeningocele had decreased leak point pressure on alpha-blocker therapy and in 2 with a history of posterior urethral valves new onset bilateral hydronephrosis completely resolved. Only 1 patient had mild postural hypotension, which resolved with dose reduction.

CONCLUSIONS

Selective alpha-blocker therapy seems to be well tolerated in children and appears effective for improving bladder emptying in various pediatric voiding disorders at short-term followup. Long-term followup and further investigation are warranted to validate the potential role of alpha-blocker therapy in pediatric urinary dysfunction.

alpha-Adrenergic blockade in children with neuropathic and nonneuropathic voiding dysfunction

PURPOSE

Inadequate bladder emptying is a common urinary dysfunction in children. The role of alpha-blockers for managing bladder outlet obstruction remains relatively unexplored in children. Because of the well established impact of alpha-blocker therapy in men, we investigated its use for treating inadequate bladder emptying in the pediatric population.

MATERIALS AND METHODS

We treated 17 children 3 to 15 years old with documented poor bladder emptying of various etiologies, including dysfunctional voiding, the Hinman syndrome, the lazy bladder syndrome, posterior urethral valves, myelomeningocele and the prune-belly syndrome, using the alpha-1 adrenergic receptor antagonist, doxazosin. The initial dose of 0.5 to 1.0 mg. nightly was increased according to patient response and as tolerated. Patients were followed weekly to monthly by symptomatic history, and urine flow and/or post-void residual urine volume measurement. Two patients with neurogenic bladder were also followed with cystometrography and leak point pressure determination.

RESULTS

Bladder symptomatology and/or emptying improved in 14 patients (82%). Ten patients had decreased post-void residual urine during treatment and in 3 uroflowmetry showed increased maximum flow. Two patients with neuropathic bladder secondary to myelomeningocele had decreased leak point pressure on alpha-blocker therapy and in 2 with a history of posterior urethral valves new onset bilateral hydronephrosis completely resolved. Only 1 patient had mild postural hypotension, which resolved with dose reduction.

CONCLUSIONS

Selective alpha-blocker therapy seems to be well tolerated in children and appears effective for improving bladder emptying in various pediatric voiding disorders at short-term followup. Long-term followup and further investigation are warranted to validate the potential role of alpha-blocker therapy in pediatric urinary dysfunction.