Besides stimulation of M3 receptors located on endothelial cells, the main mechanism of vasodilatory actions of acetylcholine includes which of the following?
Most of the blood vessels contain cholinergic M3 receptors but no parasympathetic nerve supply.
Exogenously administered ACh can stimulate M3 receptors and result in vasodilation.
Stimulation of M3 receptors increases the production of NO (endothelium-derived relaxing factor; EDRF) that causes smooth muscle relaxation resulting in vasodilation.
Vasodilation also may arise indirectly due to inhibition of NA release from nerve endings by ACh.
If endothelium is damaged, ACh can stimulate receptors on vascular smooth muscle cells resulting in vasoconstriction.
Decrease in endothelin by acetylcholine released from cholinergic nerves in blood vessels
Inhibition of norepinephrine release from adrenergic nerve endings
Stimulation of vascular smooth muscle cells
Effects on autoregulation particularly in coronary vascular beds.