Effect of local alpha-adrenergic blockade on human penile erection

Recent data suggest that selective local blockade of the alpha-adrenergic receptors of the sympathetic innervation within the corpora cavernosa of the penis will result in erection in normal and impotent subjects. To examine this hypothesis we studied in a randomized, double-blinded fashion 8 impotent patients and 2 normal controls. The organic nature of the impotence was documented with nocturnal penile tumescence testing, sacral latency examination, Doppler penile blood flow measurements, hormonal evaluation and psychological testing. The 2 normal controls had full erections for 5 to 7 minutes after the intracorporeal injection of 5 mg. phentolamine. All of the impotent subjects had tumescence without full erection after a similar injection. The tumescence was augmented by standing upright and diminished by assuming a supine posture, and lasted for several hours. Possible mechanisms, and diagnostic and therapeutic implications are discussed.