Dynamics of acute retention in prostatic patient and role of adrenergic receptors.

The dynamic changes in the lower urinary tract associated with acute retention in the prostatic patient were investigated by pressure studies. These revealed that the site of maximal urethral pressure was in the prostatic segment, the bladder neck was not tightly closed, and the normal tone of the external sphincter was inhibited. Bladder decompression altered these findings, and alpha-adrenergic blockade produced a reduction in all pressure parameters in the posterior urethra. The significance of the findings is discussed in relation to present-day knowledge of lower tract urodynamics. It is concluded that certain cases of acute retention in the prostatic patient may be initiated by stimulation of the prostatic alpha-adrenergic receptors, and may then be perpetuated by a secondary fall in intravesical pressure together with a supplementaty "feed-back" stimulation of these receptors due to the bladder overdistention itself. Decompression and/or alpha-adrenergic block may sometimes reverse this process.