Angiotensin 1-7 administration alters baroreflex sensitivity and renal function in sympathectomized rats

Abstract

Background: Renin-angiotensin system (RAS) plays an important role in cardiovascular and kidney functions to regulate the systematic blood pressure. The baroreflex sensitivity (BRS) index is a quantitative index that was considered as a prognostic indicator for cardiovascular system risk which is known as heart rate change to blood pressure change ratio ( HR MAP ∆ ∆ ). Sympathetic nerve is an arm of the BRS which may be influenced by RAS vasodilatory arm function. Objectives: To determine the role of angiotensin 1-7 (Ang1-7) accompanied by bilateral renal denervation (RDN) on BRS and renal function. Methods: Male and female anesthetized Wistar rats were subjected to RDN and treated with Ang1-7 (300 and 1000 ng.kg-1.min-1). Mean arterial pressure (MAP) and heart rate (HR) responses to phenylephrine (PE) infusion were measured to determine BRS index. As kidney function markers, the creatinine clearance (CrCl) and urine flow (UF) were also determined. Results: The results showed that BRS increased significantly in RDN male rats treated with Ang1-7 compared to vehicle (P<0.05). BRS attenuates significantly in RDN male rats treated with vehicle or Ang1-7 when compared with non-RDN (control). In female rats, the BRS decreased significantly in Ang1-7 treated group (P<0.05). Also, the BRS was significantly different between non-RDN and RDN female rats treated with Ang1-7 (P<0.05). The ClCr in female and UF in both genders increased by Ang1-7 infusion in RDN and non-RDN rats. The alteration of serum nitrite level by Ang1-7 in non-RDN and RDN groups was gender related. Conclusion: The Ang1-7 infusion could alter the BRS index in RDN rat’s gender dependently. The ClCr response to Ang1-7 infusion in male rats was dose related.

Keywords

• angiotensin 1-7
• phenylephrine
• baroreflex sensitivity
• renal denervation
• renal function
• nitric oxide