What makes HDL the healthy cholesterol?
This is the interesting part of the story. HDL does lots of good things. It has the remarkable effect of improving endothelial function, by at least two mechanisms. It lowers levels of LDL by picking up cholesterol from cellular LDL and transporting cholesterol back to the liver, where it is processed and excreted as a component of bile. Furthermore, it improves the health of vascular endothelial cells lining the arteries by stimulating the activity of eNOS. Increased activity of this enzyme stimulates the production of NO, and hence a reduction in vascular constriction, and blood pressure. This too helps lower the oxidant stress placed on the endothelial cell. Summary: The endothelial cells that line the walls of the arteries are the regulators of vascular tone and health of the artery. A key mechanism involved in regulating vascular health involves the eNOS-NO pathway. Thus, endothelial cell dysfunction is the consequence of faulty or impaired synthesis of NO by a defective endotheli
