Alamandine: Mechanism, Dosing & Research Data

Alamandine is a recently discovered heptapeptide of the renin-angiotensin system (RAS) formed by the decarboxylation of angiotensin-(1-7) or by ACE2-mediated cleavage of angiotensin A. It acts on the Mas-related G-protein-coupled receptor D (MrgD) to produce cardioprotective, vasodilatory, and anti-fibrotic effects, representing a distinct arm of the protective RAS alongside angiotensin-(1-7)/Mas.

Mechanism of Action

MrgD activation (Gi/Go-coupled) leads to NO production, eNOS phosphorylation, and cAMP modulation; net vasodilatory and cardioprotective effects
Opposing arm to Ang II/AT1R: alamandine/MrgD counterbalances vasoconstriction, inflammation, and fibrosis driven by the Ang II axis
Anti-fibrotic in heart and kidney: reduces TGF-beta1-driven collagen deposition and myofibroblast activation in pressure overload and CKD models
NO-dependent vasodilation: MrgD activation in endothelium phosphorylates eNOS at Ser1177, producing sustained vasodilation resistant to ACE inhibition
Shares several but not all effects with Ang-(1-7); alamandine does not cause the calcium-independent effects of Ang-(1-7) at Mas receptor

Research Findings

Alamandine discovered in 2013 (Lautner et al.) in human heart tissue; identified as the first known MrgD ligand in the cardiovascular context
Intracerebroventricular alamandine reduces blood pressure in SHR (spontaneously hypertensive rats) to same degree as Ang-(1-7)
Alamandine reduced cardiac fibrosis and improved ejection fraction in pressure-overload (TAC) mouse heart failure model
MrgD knockout mice show impaired response to alamandine but not to Ang-(1-7), confirming receptor specificity
Alamandine combined with Ang-(1-7): additive vasodilation and cardiac protection in rodent ischemia-reperfusion models
Alamandine levels reduced in heart failure and hypertension patients; measurement by LC-MS in clinical research settings

Research Protocols

Blood pressure studies: 1-10 nmol/kg IV bolus or 100 pmol/kg/min IV infusion in SHR or normotensive rats
Cardiac fibrosis: 1-50 mcg/kg/day SC for 14-28 days in TAC or angiotensin II-infusion fibrosis models
In vitro: 1-100 nM alamandine on cardiac fibroblasts; measure collagen I/III mRNA and TGF-beta1 signaling
MrgD binding: alamandine Kd ~5-20 nM; A779 (Mas antagonist) does not block alamandine effects; specific MrgD antagonists used

Interactions

Angiotensin-(1-7)/Mas: complementary protective RAS axis; both alamandine and Ang-(1-7) oppose Ang II but via different receptors
ACE inhibitors/ARBs: shift RAS balance toward protective arms including alamandine; may explain some cardioprotective benefits beyond Ang II blockade
MrgD antagonist (D-Pro7-Ang-(1-7) at MrgD): blocks alamandine effects specifically without affecting Ang-(1-7)/Mas signaling

Safety Profile

Endogenous RAS peptide. Not clinically used. Research doses in rodents well tolerated. Vasodilatory effects dose-dependent; no organ toxicity observed. Interest as a target for cardiovascular protective therapies.