Endothelium-derived relaxing factor vasodilation caused

The endothelium of most blood vessels releases EDRF (endothelium-derived relaxing factor), which causes marked vasodilation, in response to muscarinic stimuli. However, unlike the receptors innervated by sympathetic cholinergic fibers in skeletal muscle blood vessels, these muscarinic receptors are not innervated and respond only to circulating muscarinic agonists. 

Decrease in blood pressure Injection of acetylcholine causes vasodilation and the lowering of blood pressure. Although no innervation of the vasculature by the parasympathetic system exists, there are cholinergic receptors on the blood vessels that respond by causing vasodilation. The vasodilation is due to an acetylcholine-induced rise in intracellular Ca++—caused by the phosphatidylinositol system—that results in the formation of nitric oxide (NO) from arginine in endothelial cells.2 [Note NO is also known as endothelium-derived relaxing factor (EDRF).] (See p. 176 for more detail on nitric oxide.) In the absence of adminis-... 

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