the development of skin cancer. ~~ ~~ Thyroid diseases, which are estimated to affect 10% of the population are accompanied by profound cardiovascular changes. In particular, hyperthyroidism LY-411575 induces a high-output state, with a marked decrease in systemic vascular resistance, possibly due to local release of vasodilators in peripheral tissues as a consequence of the elevated tissue metabolism. The diminished SVR seen in hyperthyroidism has been attributed to a direct effect of T3, the biologically active form of thyroid hormone, on vascular endothelium. However, the underlying mechanisms associated with the T3 actions on the vascular smooth muscle cell are still unclear. Our group has demonstrated that T3 promoted marked NO production in VSMC by rapid nongenomic actions, which in turn contributed to vascular relaxation, suggesting the VSMC as a specific target of T3, which may represent an important factor for local control of vascular function. Several lines of evidence suggest an important contribution of the renin-angiotensin system to the actions of the thyroid hormones . Two isoforms for angiotensin II receptor have been identified in VSMC: type 1 receptor and type 2 6145492 receptor . AT2R is upregulated in certain pathological conditions such as hypertension, vascular injury, inflammation and also in hyperthyroidism. The AT2R mediates cellular differentiation and growth, and in some circumstances opposes the actions of AT1R stimulation and therefore, it is important in reducing tissue remodeling and disease progression. In addition, AT2R promotes relaxation in rat isolated resistance arteries and aortas via activation of a vasodilatory cascade involving bradykinin, nitric oxide, and guanosine cyclic 39,59-monophosphate, counteracting AT1R-induced contraction. 1 AT2R Mediates T3-Induced VSMC Relaxation Based on evidence that AT2R stimulates NO production and that NO production is increased in VSMC 
by nongenomic action of T3, as well as data showing that 9751179 thyroid hormone induces an upregulation of AT2 receptor in cardiac myocytes, we hypothesized that AT2R contributes to the decreased VSMC contraction observed during hyperthyroidism condition, which may represent an important mechanism to vascular relaxation observed in this pathology. In this study we evidenced for the first time that AT2R/Akt/NO pathway represents a novel mechanism associated with the decreased VSMC contraction promoted by thyroid hormone. Methods Ethics Statement All procedures were performed in accordance with the Guiding Principles in the Care and Use of Animals, approved by Ethics Committee for Animal Research of the Institute of Biomedical Sciences, University of Sao Paulo- Brazil and also by Georgia Health Sciences University Committee on the Use of Animals in Research and Education published by the US National Institutes of Health. 1.17 mmol/L MgSO4-7H2O, 1.56 mmol/L CaCl2-2H2O, 0.026 mmol/L EDTA, 5.5 mmol/L glucose). Aortas were cut into rings, were carefully mounted in a myograph for isometric tension recordings and were equilibrated in Krebs solution for 30 min, gassed with 5% CO2 in O2 to maintain a pH of 7.4, as described previously. Aortas rings were placed under resting tension for 1 hour with frequent buffer changes until equilibrated. In all experiments the endothelium was mechanically removed by gently rolling the lumen of the vessel on a thin metallic wire. The absence of the endothelium was verified using acetylcholine in phenylephrine pre-contracting ao
Posted inUncategorized