Mechanisms of action for α 1 -adrenoceptor blockers in storage symptoms with new insights into the micturition reflex.

Elderly patients suffering from lower urinary tract symptoms with benign prostatic hyperplasia (BPH) are widely prescribed α ₁ -adrenoceptor blockers (α ₁ -blockers) to improve voiding and storage symptoms. The mechanism of action for improvements in voiding symptoms is well understood; tonus of the urethra and prostate are decreased and urinary flow rate is increased by α ₁ -blockers. However, the mechanisms underlying storage symptoms have remained unclear, although detrusor hyperactivity has been identified as a significant factor. Previous investigations have yielded informative results, such as amelioration of reduced blood flow and afferent C-fiber activation, and the importance of the urothelium. Recently, the fascinating role of α _1A - and α _1D -adrenoceptor subtypes have been investigated for bladder function. Furthermore, the scope of this pathology covers both the bladder and that part of the central nervous system related to the micturition reflex. This review describes the beneficial effects of α ₁ -blockers on storage symptoms and the pathogenesis of storage symptoms related to BPH, discusses the mechanisms of action for α ₁ -blockers with reference to results from cystometry to suggest improvements in management that suppress detrusor hyperactivity, and examines the potential influence of α _1A - and α _1D -adrenoceptor subtypes on bladder activity.
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