Fibers, cholinergic

Nemmar A, Delaunois A, Beckers JF, Sulon J, Bloden S, Gustin P (1999) Modulatory effect of imetit, a histamine H3 receptor agonist, on C-fibers, cholinergic fibers and mast cells in rabbit lungs in vitro. Eur J Pharmacol 371 23-30... 

Cholinergic blocking dragp inhibit die activity of acetylcholine in parasympadietic nerve fibers (see Chap. 24 for a description of die role of acetylcholine in the transmission of nerve impulses across parasympadietic nerve fibers). When die activity of acetylcholine is inhibited, nerve impulses traveling along parasympadietic nerve fibers cannot pass from die nerve fiber to die effector organ or structure ... 

MANAGING CONSTIPATION. Constipation caused by decreased gastric motility can be a problem widi cholinergic dm. The nurse urges the patient to increase fluid intake up to 2000 mL daily (if healdi conditions permit), eat a diet high in fiber, and obtain adequate exercise The primary healdi care provider may prescribe a stool softener, if necessary, to prevent constipation. 

Long cholinergic preganglionic fibers short cholinergic postganglionic fibers... 

The two most common neurotransmitters released by neurons of the ANS are acetylcholine (Ach) and norepinephrine (NE). Several distinguishing features of these neurotransmitters are summarized in Table 9.3. Nerve fibers that release acetylcholine are referred to as cholinergic fibers and include all preganglionic fibers of the ANS — sympathetic and parasympathetic systems all postganglionic fibers of the parasympathetic system and sympathetic postganglionic... 

Cholinergic Relating to nerve cells or fibers that employ acetylcholine as their neurotransmitter. 

It has been repeatedly observed that atropine is more effective in blocking effects of exogenously introduced acetylcholine and other parasympathomimetics than in blocking effects resulting from stimulation of fibers of the parasympathetic and cholinergic nerves. There are two factors that could be the reason for this ... 

The myenteric and submucosal plexuses contain ganglion cells giving rise to excitatory cholinergic fibers that directly innervate the smooth muscle and gland... 

The parasympathetic nervous system, through the vagus nerve, inhibits the spontaneous rate of depolarization of pacemaker cells. The release of acetylcholine from cholinergic vagal fibers increases potassium conductance (gK+) in pacemaker cells, and this enhanced outward movement of K+ results in a more negative po-... 

Cholesterogenesis. Synthesis of cholesterol. Cholinergic. Relating to nerve fibers that cause effects similar to those induced by acetylcholine. 

Afferent cholinergic and adrenergic autonomic fibers are similarly present in detrusor and lissosphincter units and include micturition triggers linked with stretch receptors and urinary flow receptors (Gil Ver-net, 1968 Hutch, 1972 Elbadawi, 1973, 1982, 1983 Elbadawi and Schenk, 1974 de Groat and Kawatani, 1985). Some of the afferent fibers connect to reflex circuits in the sacral cord for bladder and rectum while connecting in the sacral and thoracic cord for sexual reflex circuits. 

Schematic diagram comparing some anatomic and neurotransmitter features of autonomic and somatic motor nerves. Only the primary transmitter substances are shown. Parasympathetic ganglia are not shown because most are in or near the wall of the organ innervated. Cholinergic nerves are shown in blue noradrenergic in red and dopaminergic in green. Note that some sympathetic postganglionic fibers release acetylcholine or dopamine rather than norepinephrine. The adrenal medulla, a modified sympathetic ganglion, receives sympathetic preganglionic fibers and releases epinephrine and norepinephrine into the blood. ACh, acetylcholine D, dopamine Epi, epinephrine M, muscarinic receptors N, nicotinic receptors NE, norepinephrine.

It has been known for many years that autonomic effector tissues (eg, gut, airways, bladder) contain nerve fibers that do not show the histochemical characteristics of either cholinergic or adrenergic fibers. Both motor and sensory NANC fibers are present. Although peptides are the most common transmitter substances found in these nerve endings, other substances, eg, nitric oxide synthase and purines, are also present in many nerve terminals (Table 6-1). Capsaicin, a neurotoxin derived from chili peppers, can cause the release of transmitter (especially substance P) from such neurons and, if given in high doses, destruction of the neuron. 

Vascular smooth muscle in skeletal muscle has sympathetic cholinergic dilator fibers. 

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. 

Atropine suppresses thermoregulatory sweating. Sympathetic cholinergic fibers innervate eccrine sweat glands, and their muscarinic receptors are readily accessible to antimuscarinic drugs. In adults, body temperature is elevated by this effect only if large doses are administered, but in infants and children even ordinary doses may cause "atropine fever."... 

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