47 - Disrupting caveolae promotes eNOS uncoupling and ROS production

Abstract

Caveolae are plasma membrane invaginations enriched with high cholesterol and sphingolipid content; they also contain caveolin proteins in their structure. Endothelial nitric oxide synthase (eNOS) is highly concentrated in plasma membrane caveolae. Hypertension is associated with decreased nitric oxide (NO) production and impaired endothelium-dependent relaxation. Therefore, we aimed to investigate caveola integrity and density in SHR aortas and mesenteric arteries and the role played by caveolae in endothelium-dependent relaxation. We showed the presence of caveola-like structures in SHR aortas and mesenteric arteries. Increased phenylephrine-induced contractile response after treatment with dextrin was related to lower NO release. In addition, impaired acetylcholine-induced endothelium-dependent relaxation could be related to decreased caveola density in SHR vessels. Cholesterol depletion with dextrin induced eNOS phosphorylation at Serine1177 (Ser1177) and boosted reactive oxygen species (ROS) production in Wistar rat and SHR vessels, which suggested eNOS uncoupling. Human umbilical vein endothelial cells (HUVECs) treated with dextrin confirmed eNOS uncoupling, as verified by the reduced eNOS dimer/monomer ratio. BH4, L-arginine, or BH4 plus L-arginine inhibited eNOS monomerization. The results showed that caveola structure and its integrity are essential for endothelium-dependent relaxation. Additionally, a smaller number of caveolae is associated with hypertension. Finally, caveola disruption promotes eNOS uncoupling in normotensive and hypertensive rat vessels and in HUVECs.