[Comparison of selective alpha-1 blockades for alpha-receptors in human hypertrophied prostatic adenomas]

The adrenergic alpha-1 and -2 adrenoceptors in six human hypertrophied prostatic adenomas were measured in the saturation experiment using 3H-prazosin and 3H-yohimbine. Not only alpha-1 adrenoceptons, but also alpha-2 adrenoceptors were found to exist in large amounts in prostatic adenomas. In the inhibition experiment selective alpha-1 antagonists inhibited the 3H-prozosin or 3H-yohimbine bindings to adenomas. The potency of alpha-1 antagonists in the order prazosin greater than bunazosin greater than alfuzosin greater than urapidil greater than terazosin and that of alpha-2 antagonists is urapidil greater than alfuzosin greater than terazosin greater than bunazosin greater than prazosin. These data suggest that urapidil, alfuzosin and terazosin may affect the human hypertrophied prostatic adenoma like phenoxybenzamine, nonselective alpha-1 antagonist, which was used for benign prostatic hypertrophy.