Quantificação temporal de componentes do sistema renina angiotensina no período claro/escuro

Abstract

The Renin-Angiotensin System (RAS) is a neuroendocrine component of the organism, which can be circulating or local - expressed in tissues -, and it plays a crucial role as a modulator of homeostasis. It can be divided into two functional axes: the canonical axis, with hypertensive, fibrotic, and proliferative effects, and the non-canonical axis, which counteracts these effects, inducing generally protective responses. It has been observed that several physiological processes have a pattern of oscillation over time, influenced mainly by exposure to light and the expression of “clock genes” throughout the day. These cyclic changes are essential for the homeostasis of the systems. However, the oscillations of the components of the RAS have not been fully elucidated, although there are strong indications that this system undergoes temporal changes. For instance, a higher incidence of vascular accidents is observed in the morning, fluctuations in blood pressure throughout the day, changes in the activity of the enzyme Renin and in the concentrations of Angiotensin II, quantified through the radioimmunoassay technique. Therefore, this study aimed to evaluate whether the circulating peptide components of RAS indeed undergo temporal alterations in their concentrations using liquid chromatography coupled with targeted mass spectrometry (LC-MRM). Our results showed that, with the exception of Ang A all quantified peptides showed some degree of variation in their concentrations at different time points (ZTs) tested, demonstrating that the circulating peptides of both the canonical and non-canonical axis have temporal variations. However, the mechanism by which the plasma concentration of such peptides is regulated throughout the day still needs to be elucidated.