Alpha-adrenergic mechanisms in dynamics of benign prostatic hypertrophy.

Smooth muscle tone in the enlarged prostate is directly related to stimulation of the alpha-adrenergic receptors present in prostatic tissue. Variations in tone produce corresponding alterations in the degree of prostatic obstruction. Such variations can explain the spontaneous symptomatic variations seen clinically in benign prostatic hypertrophy (BPH), and represent a "dynamic component" in obstruction which is superimposed on the underlying basic "mechanical component." The obstructive symptoms posed by the dynamic component can be reduced to a minimum by pharmacologic blockade of the alpha-adrenergic receptors. Alpha-blockade can also reduce irritative symptoms. Acute obstruction due to overstimulation of alpha-receptors can be relieved or prevented by alpha-blockade.