Vargas F, Fernandez-Rivas A, Osuna A
Departamento de Fisiolgía, Facultad de Medicina, U. Experimental, Granada, Spain.
Eur J Endocrinol. 1996 Oct;135(4):506-13. doi: 10.1530/eje.0.1350506.
In the present study we evaluated the effects of methimazole, an antithyroid drug, on blood pressure and other variables in the early and established phases of hypertension induced by the inhibition of nitric oxide synthesis with the oral administration of NG-nitro-L-arginine methyl ester (L-NAME), 75 mg/100 ml in the drinking water. Moreover, we also evaluated the acute pressor effect of L-NAME on systemic blood pressure in control and rats treated chronically with methimazole, administered via drinking water (30 mg/100 ml). Oral administration of methimazole maintained the blood pressure of L-NAME-treated rats at normal levels 25 days after induction of hypertension. However, after 25 days of methimazole treatment in rats made hypertensive with L-NAME (for 25 days), high blood pressure was similar in methimazole-treated and non-treated L-NAME rats, despite the fact that a hypothyroid state had been achieved in the methimazole-treated rats. Acute intravenous injection of L-NAME caused a similar increase in mean arterial pressure in control and methimazole-treated rats at the lowest dose; however, smaller pressor responses were observed with increasing doses in hypothyroid rats. These results clearly demonstrate that hypothyroidism induced by methimazole prevents, but does not reverse, L-NAME hypertension and reduces the acute pressor responsiveness to L-NAME administration.
在本研究中，我们评估了抗甲状腺药物甲巯咪唑对通过口服N-硝基-L-精氨酸甲酯（L-NAME，饮用水中浓度为75 mg/100 ml）抑制一氧化氮合成所诱导的高血压早期和确立期的血压及其他变量的影响。此外，我们还评估了L-NAME对对照组和长期饮用含甲巯咪唑（30 mg/100 ml）水的大鼠的全身血压的急性升压作用。口服甲巯咪唑可使L-NAME处理的大鼠在高血压诱导后25天血压维持在正常水平。然而，在用L-NAME使大鼠高血压25天后，再用甲巯咪唑治疗25天，尽管甲巯咪唑处理的大鼠已达到甲状腺功能减退状态，但甲巯咪唑处理组和未处理的L-NAME大鼠的高血压情况相似。在最低剂量时，急性静脉注射L-NAME可使对照组和甲巯咪唑处理的大鼠平均动脉压有相似的升高；然而，随着剂量增加，甲状腺功能减退大鼠的升压反应较小。这些结果清楚地表明，甲巯咪唑诱导的甲状腺功能减退可预防但不能逆转L-NAME高血压，并降低对L-NAME给药的急性升压反应性。
