Skeletal muscle cholinergic transmission

Mechanism of Action A cholinergic drug that prevents destruction of acetylcholine by inhibiting the enzyme acetylcholinesterase, thus enhancing impulse transmission across the myoneural junction. Therapeutic Effect Improves intestinal and skeletal muscle tone stimulates salivary and sweat gland secretions. 

Anticholinesterase insecticides phosphorylate the active site of cholinesterase in all parts of the body. Inhibition of this enzyme leads to accumulation of acetylcholine at affected receptors and results in widespread toxicity. Acetylcholine is the neurohormone responsible for physiologic transmission of nerve impulses from preganglionic and postganglionic neurons of the cholinergic (parasympathetic) nervous system, preganglionic adrenergic (sympathetic) neurons, the neuromuscular junction in skeletal muscles, and multiple nerve endings in the central nervous system (Fig. 10-5). 

CHARACTERISTICS OF CHOLINERGIC TRANSMISSION AT VARIOUS SITES Skeletal Muscle... 

The primary pathway of cholinergic transmission in autonomic ganglia is similar to that at the neuromuscular junction of skeletal muscle. The initial depolarization is the result of activation of nicotinic ACh receptors, which are ligand-gated cation channels with properties similar to those found at the neuromuscular junction. Several secondary transmitters or modulators either enhance or diminish the sensitivity of the postganglionic cell to ACh. Ganglionic transmission is discussed in more detail in Chapter 9. 

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