The roles of angiotensin-converting enzyme 2 inhibitor, melatonin and its agonist on angiotensin II reactivity in intact and denuded rat aortic rings.

Background: The pineal product melatonin (MEL) modulates blood vessels through G protein-coupled receptors (GPCRs) called melatonin type 1 receptor (MT₁R) and melatonin type 2 receptor (MT₂R), in that order. The renin-angiotensin system (RAS), which breaks down angiotensin II (Ang II) to create Ang 1-7, is thought to be mostly controlled by angiotensin-converting enzyme-2 (ACE₂).

Aim: The current work examines the involvement of ACE₂ inhibitor, MEL, and ramelteon (RAM) in the vascular response to Ang II activities in the endothelial denuded (E-) and intact (E+) rat isolated thoracic aortic rings.

Method: The isometric tension was measured to evaluate the vascular Ang II contractility using dose response curve (DRC).

Results: MEL and RAM caused a rightward shift of Ang II in endothelium E + and endothelium E- aorta.

Conclusion: According to the current study, the distribution of MEL receptors and the endothelium's condition are related to the vasomodulatory effect of MEL and ACE₂ on Ang II attenuation. These physiological interactions can control vascular tone and increase Ang II reactivity denude endothelial layaer.