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Hyperthyroid rats display increased adrenergic ‐mediated contraction in cavernosal tissue
Author(s) -
Carneiro Zidonia Nunes Noetzold,
Carrillo Sepulveda Maria Alicia,
Carneiro Fernando Silva,
Giachini Fernanda Regina,
Lima Victor Vitorino,
Webb R Clinton,
Tostes Rita C
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.781.6
Subject(s) - endocrinology , medicine , contractility , phenylephrine , myograph , contraction (grammar) , erectile tissue , stimulation , nitric oxide , adrenergic , sympathetic nerve , erectile dysfunction , vasodilation , blood pressure , receptor
Disturbances in thyroid function lead to sexual dysfunction in humans. However, the mechanisms by which hyperthyroidism causes erectile dysfunction (ED) are unknown. Whereas nitric oxide (NO) is the mediator of erection, sympathetic activation causes detumescence. Objective We hypothesized that hyperthyroidism increases sympathetic‐mediated contractility in cavernosal tissue. Methods and Results Wistar male rats were submitted to experimental hyperthyroidism (70ug/Kg T3 for 14 days). Thyroid hormone T3 plasmatic levels were increased in hyperthyroid animals (Hyper) (Control: 0.43±0.08 vs Hyper: 1.45±0.64, ng/mL). After euthanasia, penises were excised and dissected. Cavernosal strips were mounted in a myograph and stretched to a resting force of 3.0 mN. Cavernosal contractility to phenylephrine (PE) (Control: 1.72±0.2 vs Hyper: 3.06±0.2, mN) and sympathetic‐nerve stimulation (Control: 0.9±0.4 vs Hyper: 2.03±0.3, mN) were increased in Hyper rats. Cavernosal responses to nonadrenergic‐noncholinergic‐mediated relaxation and endothelium‐independent relaxation were not altered. Conclusion Our results suggest that increased sympathetic‐ mediated responses contribute to ED in hyperthyroidism.