Some pharmacologic effects of yohimbine on human and rabbit penis.

The pharmacologic effects of yohimbine on human and rabbit penile tissue were studied in 2 experimental systems. Yohimbine (10(-7) to 10(-4) M), in a dose-related manner, partially antagonized norepinephrine-induced contraction of human corpus cavernosum in an in vitro muscle bath. Yohimbine alone, however, did not alter the baseline tension of strips of human corpus cavernosum. The catecholamine content of the corpus cavernosum and corpus cavernosum urethrae of saline (control) and yohimbine-treated rabbits was determined by high pressure liquid chromatography. There was no statistically significant difference in mean norepinephrine content between control (0.38 +/- 0.29 microgram. per gm. wet wt.) and yohimbine-treated (0.25 +/- 0.21 microgram. per gm. wet wt. at 1 mg. per kg. body wt.; 0.50 +/- 0.10 microgram. per gm. wet wt. at 2 mg. per kg. body wt.) rabbit corpus cavernosum and control (0.53 +/- 0.34 microgram. per gm. wet wt.) and yohimbine-treated (0.86 +/- 32 microgram. per gm. wet wt. at 1 mg. per kg. body wt.; 0.53 microgram. per gm. wet wt. at 2 mg. per kg. body wt.) rabbit corpus cavernosum urethrae. It appears that, in the penis, yohimbine exhibits alpha adrenergic blocking properties and does not affect catecholamine levels in this tissue.