Papéis das vias do óxido nítrico e das prostaglandinas nos efeitos antihipertensivos sustentados em ratas ovariectomizadas com hipertensão renovascular tratadas com extrato aquoso de Acanthospermum hispidum DC

Abstract

Systemic arterial hypertension is a chronic multifactorial disease, defined by systolic/diastolic blood pressure above 140/90 mm Hg, which presents a high prevalence in the world population, for its treatment, besides the use of pharmacological therapies, a therapeutic alternative is the combination of conventional medicines with different natural products. In this context is Acanthospermum hispidum DC, a medicinal plant that belongs to the Asteraceae family whose aerial parts are popularly used for diuretic and antihypertensive purposes. Despite the relevance of this species throughout the country, there are no detailed studies that evaluated its effects in a model of renovascular hypertension associated with ovariectomy (2K1C plus OVT). Thus, this study investigated the mechanisms involved in the antihypertensive effects of a soluble ethanol fraction obtained from A. hispidum (ESAH) using 2K1C plus OVT as a model. Five weeks after surgery, ESAH was administered orally at doses of 30, 100 and 300 mg / kg daily for 28 days. Enalapril (15 mg / kg) and hydrochlorothiazide (25 mg / kg) were used as standard drugs. Diuretic activity was assessed on days 1, 7, 14, 21 and 28. Systolic, diastolic and mean blood pressure and heart rate were recorded. Serum levels of creatinine, urea, thiobarbituric acid, nitrosamine, nitrite, aldosterone, vasopressin and plasma angiotensin converting enzyme (ACE) activity were also measured. Vascular reactivity and the roles of nitric oxide (NO) and prostaglandins (PG) in the vasodilator response of ESAH to mesenteric vascular bed (MVB) were also investigated. Treatment with ESAH induced a significant saline and antihypertensive response, recovering vascular reactivity in 2K1C plus OTV rats. This effect was associated to the reduction of oxidative and nitrosative stress with possible increase of NO bioavailability. In addition, a vasodilatory effect dependent on NO and PG was also observed in LVM.