Respostas cardiovasculares à fração acetato de etila do extrato de Erythroxylum suberosum em ratos normotensos e espontaneamente hipertensos

Abstract

Arterial hypertension is a chronic non-communicable disease characterized by a persistent increase in blood pressure within blood vessels, which can lead to various complications. Its treatment primarily relies on pharmacological intervention using different classes of antihypertensive drugs. However, the pursuit of alternative therapies, such as the use of herbal medicines, has significantly increased. Brazil is home to extensive biodiversity, with the cerrado biome representing a large portion of its flora. Among its diverse species, Erythroxylum suberosum (E.suberosum) stands out due to the presence of compounds such as tannins and flavonoids in its plant extract, making it apotential herbal therapy for cardiovascular diseases. Therefore, it is relevant to evaluate cardiovascular responses, including mean arterial pressure (MAP), heart rate (HR), renal blood flow (RBF), aortic blood flow (ABF), renal vascular resistance (RVR), and aortic vascular resistance (AVR), induced by the infusion of the ethyl acetate fraction of E.suberosum extract in normotensive (Wistar) and spontaneously hypertensive rats (SHR). The experimental protocol involved two groups: SHR and normotensive rats (250-350g), which were anesthetized (inhalation induction with 2% isoflurane in 100% oxygen followed by intravenous infusion of urethane at 1.2 g/kg). The animals were then subjected to surgical procedures to monitor and evaluate the cardiovascular parameters. Administration of the vehicle (5% DMSO) and four extract doses (0.75, 1.5, 3, and 6 mg/kg) was performed randomly. As a result, the three highest doses of the extract showed a significant difference in the reduction of the MAP response between the groups. Regarding HR, only the doses of 1.5 mg/kg and 3 mg/kg promoted a reduction in the HR response in hypertensive rats compared to normotensive ones. Observing the RBF values, no significant differences were observed between the normotensive and hypertensive groups and only the dose of 3 mg/kg was able to promote an increase in the ABF response, when comparing the groups. There was a reduction in RVR values in hypertensive animals after a dose of 1.5 mg/kg, demonstrating a vasorelaxation effect in the renal bed. All doses of the extract promoted significant differences in reduction in RVA indices in hypertensive rats and also when comparing the groups. Taken together, the data presented allow us to conclude that the ethyl acetate portion of the E.suberosum extract has the capacity to promote an antihypertensive response in hypertensive animals through vasorelaxant activity mainly in the aortic bed.