Muscarinic acetylcholine receptors are integral membrane proteins located on the surface of cells receiving signals from the parasympathetic nervous system. These receptors play a crucial role in mediating the effects of acetylcholine, a neurotransmitter released from parasympathetic nerve endings. Activation of these receptors initiates a cascade of intracellular events leading to diverse physiological responses depending on the target cell type. For example, in cardiac muscle, activation leads to a decrease in heart rate.
The presence of these receptors on target cells is essential for proper parasympathetic function, which is responsible for the “rest and digest” response in the body. This system regulates vital functions such as digestion, heart rate, and glandular secretions. Historically, the identification and characterization of these receptors significantly advanced our understanding of how the parasympathetic nervous system exerts its effects at the cellular level, paving the way for the development of drugs targeting these receptors for various therapeutic purposes.
