REACTIVITY OF HUMAN DEFERENTIAL ARTERY TO CONSTRICTOR AND DILATOR SUBSTANCES

The present study was designed to investigate general morphology and t he response of human deferential artery to constrictor and dilator sub stances with special emphasis on endothelium-dependent responses. Huma n deferential artery segments were obtained from patients undergoing r adical cystectomy (n = 7), suprapubic prostatectomy (n = 6), or radica l prostatectomy (n = 6). Light microscopy revealed that human deferent ial artery is of muscular type, and fluorescence microscopy showed a d ense adrenergic innervation. Paired rings, one normal and the other de -endothelialized by gentle rubbing, were mounted for isometric recordi ng of tension in organ baths. Vasopressin, endothelin, serotonin, and potassium chloride induced endothelium-independent contractions, where as norepinephrine and electrical field stimulation caused frequency-de pendent contractions that were of greater magnitude in arteries denude d of endothelium. In precontracted arterial rings, acetylcholine and s ubstance P induced endothelium-dependent relaxations. In contrast, pap averine and sodium nitroprusside caused concentration-dependent relaxa tions that were similar in the presence and in the absence of endothel ium. NG-nitro-L-arginine methyl ester (10(-4) M), an inhibitor of nitr ic oxide synthase, potentiated the responses to norepinephrine in arte ry rings with endothelium, nearly abolished the acetylcholine-induced relaxation, and attenuated the relaxation induced by substance P. Incu bation with methylene blue (10(-5) M), an inhibitor of guanylate cycla se, completely prevented the relaxation induced by acetylcholine in ar teries with endothelium. The results of this study indicate that the h uman deferential artery has a dense adrenergic innervation and marked ability to contract or relax in response to different agonists. Some o f these responses are in part endothelium dependent and mediated throu gh release of nitric oxide. These morphological and pharmacological ob servations could play an important role in regulating flow or pressure of blood that arrives to the vas deferens.