Endothelium-dependent relaxation (EDR)

Endothelium-dependent relaxation (EDR) is a critical physiological process where the vascular endothelium releases signaling molecules to induce the relaxation of the underlying smooth muscle, thereby regulating blood flow and pressure (Furchgott & Zawadzki, 1980). This phenomenon is primarily mediated by the production of nitric oxide (NO) by endothelial nitric oxide synthase (eNOS) in response to physical stimuli like shear stress or chemical agonists such as acetylcholine (Vanhoutte et al., 2017). NO diffuses into smooth muscle cells and activates soluble guanylate cyclase (sGC), which increases cyclic GMP levels to trigger relaxation. A decrease in EDR capacity is a hallmark of endothelial dysfunction and serves as a major precursor and systemic marker for cardiovascular diseases, including hypertension and atherosclerosis (StatPearls, 2023). Pharmacological strategies to enhance EDR include the use of statins to increase eNOS expression, ACE inhibitors to prevent the breakdown of bradykinin, and phosphodiesterase inhibitors to prolong cGMP activity (PubMed, PMID: 15653439). Maintaining robust EDR is essential for preventing vascular inflammation and thrombotic events.

Other names

Endothelium-mediated vasodilationEndothelium-derived relaxationAcetylcholine-induced relaxationEDRF-mediated relaxation

Stimulation of endothelial cells by agonists or shear stress triggers the synthesis of Nitric Oxide (NO) and other factors; NO then diffuses into vascular smooth muscle cells where it activates soluble guanylate cyclase (sGC), increasing cGMP and leading to muscle relaxation and vasodilation.