Impaired neurogenic and endothelium-dependent relaxant responses of corpus cavernosum smooth muscle from hyperthyroid rabbits

• Published in: European journal of pharmacology 2001-09, Vol.428 (1), p.105-111
• Main Authors: Özdemirci, Sitki, Yildiz, Fürüzan, Utkan, Tijen, Ulak, Güner, Çetinaslan, Berrin, Erden, Faruk, Gacar, Nejat
• Format: Article
• Language: English
• Subjects: Acetylcholine - pharmacology; Animals; Biological and medical sciences; Contraction; Corpus cavernosum; Electric Stimulation; Endocrinopathies; Endothelium, Vascular - drug effects; Endothelium, Vascular - innervation; Endothelium, Vascular - physiology; Hyperthyroidism; Hyperthyroidism - chemically induced; Hyperthyroidism - physiopathology; In Vitro Techniques; Male; Medical sciences; Muscle Relaxation - drug effects; Muscle Relaxation - physiology; Muscle, Smooth - drug effects; Muscle, Smooth - innervation; Muscle, Smooth - physiopathology; Nitroprusside - pharmacology; Non tumoral diseases. Target tissue resistance. Benign neoplasms; Penis - drug effects; Penis - physiopathology; Potassium Chloride - pharmacology; Rabbits; Relaxation; Thyroid. Thyroid axis (diseases); Thyroxine - pharmacology; Vasodilator Agents - pharmacology
• ISSN: 0014-2999; 1879-0712
• DOI: 10.1016/S0014-2999(01)01268-7

We investigated the effect of hyperthyroidism on the responsiveness of the rabbit corpus cavernosum smooth muscle. In male albino rabbits, hyperthyroidism was established by oral feeding of l-thyroxine at increasing dosages (150–450 μg/kg) over an 8-week period. This treatment produced a stable hyperthyroid state as indicated by the increased serum T 4 levels. The reactivity of corpus cavernosum tissue from hyperthyroid animals and euthyroid control animals was studied in organ chambers. Hyperthyroidism caused impaired neurogenic and endothelium-dependent relaxant responses with decreased E max and p D 2 values. However, hyperthyroidism had no effect on both phenylephrine- and KCl-induced contractile responses and sodium nitroprusside- and papaverine-induced endothelium-independent relaxant responses, and there was no change in agonist potency. These data indicate that hyperthyroidism may impair both neurogenic and endothelium-dependent relaxation of corporal smooth muscle, and may contribute to the etiology of impotence.