EVALUATION OF AUTONOMIC DYSFUNCTION UTILIZING ACETYLCHOLINE CHALLENGES

By: Evan Mladenoff BSC, DC, DIBAK, FASA

Otto Loewi 1921 German Nobel Prize winning Physiologist stimulated the Vagus Nerve that caused reduction in heart rate by triggering the release of Acetylcholine The first neurotransmitter ever discovered. . . .

Acetylcholine (ACh) is THE neurotransmitter in the first order neuron of the somatic nervous system and the autonomic nervous system and is necessary for most nerve functions In the first diagram note the following: a) In the somatic nervous system ACh is responsible for skeletal muscle contraction. This occurs via the muscarinic receptors. b) In the sympathetic nervous system, ACh is the first order neuron neurotransmitter that synapses with unmyelinated postganglionic axons to produce norepinephrine c) In the sympathetic nervous system, ACh is the first order neuron neurotransmitter that synapses with the adrenal medulla to initiate epinephrine and norepinephrine production for release into the circulatory system d) In the parasympathetic nervous system, ACh is the first order neuron neurotransmitter that synapses with unmyelinated postganglionic axons to continue ACh transmission that affects/controls smooth muscle (in the gut), glands and cardiac muscle

Acetylcholine has many roles:

When it binds to muscarinic receptors, it:

Regulates heart contractions and blood pressure and decreases heart rate

Moves food through your intestine by contracting intestinal muscles and increasing stomach and intestine secretions

Causes glands to secrete substances such as tears, saliva, milk, sweat and digestive juices

Controls the release of urine

Contracts muscles that control near vision Causes an erection

When it binds to nicotinic receptors, it:

Allows skeletal muscle to contract.

Causes the release of adrenaline and norepinephrine from your adrenal glands

Activates your sympathetic system with the release of norepinephrine