Contractile Properties of Prostatic Strips in Different Histological Types of Obstructive Benign Prostatic Hypertrophy

Abstract

Smooth muscle contraction was performed in vitro in thirty-three patients proven to have prostatic obstruction in order to clarify the relationship of the histology and the contractility of the prostatic strips. The mean age was 71 years (59-81), 16 patients presented with dysuria and 17 with urine retention. Phenylephrine (PE) and norepine phrine (NE) (10-7 to 10-4 M) were used as alpha-adrenoceptor stimulation. Prazosin (10-10 to 10-7 M) was used as selective alpha-1 antagonist to inhibit contraction of prostatic strips. The histological examination was classified according to the stoma/gland ratio and the degree of inflammation. The prostatic strips showed a concentration- dependent contraction on PE and NE. There was no significant difference in the contractility on PE and NE between patients with prostatism and retention; nor among the prostates of different size. The contractility showed significant difference in the histology of the prostatic strips: bladder neck smooth muscle ＞ stroma predominant ＞ gland predominant. However, the similarity in histology of the prostatic strips did not correlate well in different parts of the same prostaic gland. The result of this study proves that prostate is rich in alpha-adrenergic receptors with alpha-1 predominant. The histology will affect the contractility of prostatic strips to drugs. However, it should be careful in interpretation of the muscle strip experimental results since great difference might exist in different parts of the prostatic gland.