NITRIC OXIDE SYSTEM IN AGED HYPOTHYROID RATS

SARATI LORENA IVONNE; MARTINEZ CARLA; BALASZCZUK ANA MARÍA; FELLET ANDREA

Londres

Congreso; ESH 2012; 2012

NITRIC OXIDE SYSTEM IN AGED HYPOTHYROID RATS Objective: This study investigates whether changes in nitric oxide (NO) production participate in the cardiovascular manifestations of hypothyroidism and whether these changes are age- related. Design and method: Sprague-Dawley rats aged 2 and 18-mo-old were treated with 0.02% methimazole (w/v) during 28 days. Left ventricular function was evaluated by echocardiography. Arterial blood pressure, heart rate, nitric oxide synthase (NOS) activity and NOS/caveolins-1 and 3 protein levels were measured. Results: Hypothyroidism enhanced the heart function age-related changes. Hypothyroid state decreased atria NOS activity in young and adult rats associated with a reduction of the three NOS isoforms protein levels in young animals and an increased caveolin (cav) 1 expression in adult rats. Ventricle and aorta NOS activity increased in young and adult hypothyroid animals. In ventricle, changes of NOS activity were accompanied by an increased inducible NOS isoform in young rats and by an increased caveolins expression in adult rats. The greater aorta NOS activity in the Hypo groups would come from the inducible and endothelial NOS isoform in the young and adult rats, respectively. Conclusions: 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 the ageing-induced changes in the myocardium and aorta tissues. Low thyroid hormones levels would enhance the heart ageing effect. Age-related changes in NO production participate in the cardiovascular manifestations of hypothyroidism.