Hypothyroidism: age-related influence on cardiovascular nitric oxide system in rats.

LI. SARATI; CR. MARTÍNEZ; N. ARTÉS; N. ARRECHE; JJ. LÓPEZ; AM. BALASZCZUK; AL. FELLET

METABOLISM-CLINICAL AND EXPERIMENTAL

W B SAUNDERS CO-ELSEVIER INC

Lugar: Philadelphia; Año: 2012 vol. 61 p. 1301 - 1311

0026-0495

This study investigates whether changes in nitric oxide (NO) production participate in the cardiovascular manifestations of hypothyroidism and whether these changes are age-related. Sprague-Dawley rats aged 2 and 18 months old were treated  with o.02% methimazole (wt/vol) during 28 days. Left ventricular function was evaluated by echocardiography. Measurements of arterial blood pressure, heart rate, nitric oxide synthase activity (NOS) and NOS/caveolin-1 and -3 proetin levles were performed. Hypothyroidism enhanced the age-related changes in heart function. Hypothyroid state decreased atrial NOS activity in both young and adult rats, associated with a reduction in protein levels of the three NOS isoforms in young animals and increased caveolin (cav) 1 expression in adult rats. Ventricle and aorta NOS activity increased in young and adult hypothyroid animals. In ventricle, changes in NOS acitivity were accompanied by an increase in caveolins expression in adult rats. Greater aorta NOS activity level in young and in adult hypo rats would derive from the inducible and the endothelial NOS isoform, respectively. Thyroid hormones would be one of the factors involved in the modulation of cardiovascular NO production and caveolin-1 and -3 tissue-specific abundance, regardless of age. Hypothyroidism appears to contribute in a differential way to aging-induced changes in the myocardium and aorta tissues. Low thyroid hormones levels would enhance the aging effect of the heart. Age-related changes in NO production participate in the cardiovascular manifestations of hypothyroidism.