# Table of neurotransmitter actions in the ANS

This is a table of neurotransmitter actions in the ANS (autonomic nervous system). It includes the circulatory system, the respiratory system, the visual system, the digestive system, the endocrine system, the urinary system, the reproductive system, and the integumentary system. Both effects of the sympathetic nervous system (adrenergic) and parasympathetic nervous system (muscarinic) are included.

## Circulatory system
### Heart

| Target | Sympathetic (adrenergic) | Parasympathetic (muscarinic) |
| cardiac output | β1, (β2): increases | M2: decreases |
| SA node: heart rate (chronotropic) | β1, (β2): increases | M2: decreases |
| Atrial cardiac muscle: contractility (inotropic) | β1, (β2): increases | M2: decreases |
| at AV node | β1: increases conduction increases cardiac muscle automaticity | M2: decreases conduction Atrioventricular block |
| Ventricular cardiac muscle | β1, (β2): increases contractility (inotropic) increases cardiac muscle automaticity | --- |

### Blood vessels

| Target | Sympathetic (adrenergic) | Parasympathetic (muscarinic) |
| vascular smooth muscle in general | α1: contracts; β2: relaxes | M3: relaxes |
| renal artery | α1: constricts | --- |
| larger coronary arteries | α1 and α2: constricts | --- |
| smaller coronary arteries | β2: dilates | --- |
| arteries to viscera | α: constricts | --- |
| arteries to skin | α: constricts | --- |
| arteries to brain | α1: constricts | --- |
| arteries to erectile tissue | α1: constricts | M3: dilates |
| arteries to salivary glands | α: constricts | M3: dilates |
| hepatic artery | α: constricts | --- |
| arteries to skeletal muscle | β2: dilates | --- |
| Veins | α1 and α2: constricts β2: dilates | --- |

### Other

| Target | Sympathetic (adrenergic) | Parasympathetic (muscarinic) |
| platelets | α2: aggregates | --- |
| mast cells - histamine | β2: inhibits | --- |

## Respiratory system

| Target | Sympathetic (adrenergic) | Parasympathetic (muscarinic) |
| smooth muscles of bronchioles* | β2: relaxes (major contribution) α1: contracts (minor contribution) | M3: contracts |
$^✱$ The bronchioles have no sympathetic innervation, but are instead affected by circulating adrenaline

## Visual system

| Target | Sympathetic (adrenergic) | Parasympathetic (muscarinic) |
| Pupil dilator muscle | α1: Dilates (causes mydriasis) | |
| Iris sphincter muscle | - | M3: contracts (causes miosis) |
| Ciliary muscle | β2: relaxes (causes long-range focus) | M3: contracts (causes short-range focus) |

## Digestive system

| Target | Sympathetic (adrenergic) | Parasympathetic (muscarinic) |
| salivary glands: secretions | β: stimulates viscous, amylase secretions α1: stimulates potassium secretions | M3: stimulates watery secretions |
| lacrimal glands (tears) | β: stimulates protein secretion | secretion of tears by stimulating muscarinic receptors (M3) |
| juxtaglomerular apparatus of kidney | β1: renin secretion | --- |
| parietal cells | --- | M1: Gastric acid secretion |
| liver | α1, β2: glycogenolysis, gluconeogenesis | --- |
| adipose cells | β1, β3: stimulates lipolysis | --- |
| GI tract (smooth muscle) motility | α1, α2, β2: decreases | M3, (M1): increases |
| sphincters of GI tract | α1, α2, β2: contracts | M3: relaxes |
| glands of GI tract | no effect | M3: secretes |

## Endocrine system

| Target | Sympathetic (adrenergic) | Parasympathetic (muscarinic) |
| pancreas (islets) | α2: decreases insulin secretion from beta cells, increases glucagon secretion from alpha cells | M3: increases secretion of both insulin and glucagon. |
| adrenal medulla | N (nicotinic ACh receptor): secretes epinephrine and norepinephrine | --- |

## Urinary system

| Target | Sympathetic (adrenergic) | Parasympathetic (muscarinic) |
| Detrusor urinae muscle of bladder wall | β2, β3: relaxes | M3: contracts |
| internal urethral sphincter | α1: contracts | M3: relaxes |

## Reproductive system

| Target | Sympathetic (adrenergic) | Parasympathetic (muscarinic) |
| uterus | α1: contracts (pregnant) β2: relaxes (non-pregnant) | --- |
| genitalia | α1: contracts (ejaculation) | M3: erection |

## Integumentary system

| Target | Sympathetic (muscarinic and adrenergic) | Parasympathetic |
| sweat gland secretions | α1: stimulates (minor contribution) | M: stimulates (major contribution) |
| arrector pili | α1: stimulates | --- |