Adrenergic Receptor Subtypes & Functions

Major blood vessels and vasculature in dermal, GI, renal, bladder, and nasal membranes (α1)

Vasoconstriction, ↑peripheral resistance, ↑diastolic blood pressure

Eye (α1)

Contraction of radial muscles → mydriasis

Bladder & GI sphincters (α1)

Constrict sphincters, ↓outflow

Prostate capsule around urethra (α1)

Constrict, ↓outflow

Eye (α2)

↓ Quantity of aqueous humor

Presynaptic nerve terminals (α2)

↓ Neurotransmitter release

Brainstem (α2)

↓ Blood pressure, inhibit baroreflex

Spinal cord (α2)

Inhibit pain transmission

Heart (β1)

↑ Heart rate, ↑ contractility → ↑ cardiac output

Kidney (β1)

↑ Renin secretion → vasoconstriction

Eye (β1)

↑ Production of aqueous humor

Hepatic & skeletal muscle vascular smooth muscle (β2)

Relaxation, ↑ blood flow

Pulmonary smooth muscle (β2)

Relaxation → ↑ airflow

GI longitudinal smooth muscle (β2)

Relaxation, ↓ motility

Pregnant uterus (β2)

Relaxation

Skeletal muscle (β2)

↑ Glucose uptake, ↑ K+ uptake, metabolism

Mast cells (β2)

↓ Degranulation

Liver (β2)

↑ Glycogenolysis → ↑ blood glucose

Eye (β2)

↑ Production of aqueous humor

Bladder detrusor muscle (β3)

Relaxation