Table of neurotransmitter actions in the ANS
# Table of neurotransmitter actions in the ANS

## 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 | --- |
