Roles of Beta2- and Beta3-Adrenoceptor Polymorphisms in Hypertension and Metabolic Syndrome

Table 1

Comparisons of adrenergic receptor subtypes.

Receptor type	Agonist potency order	Action sites	Functions
α 1-adrenoceptor	norepinephrine≥	blood vessels of skim, gastrointestinal, kidney	vasoconstriction
	epinephrine⋙	ureter, uterus, urethral sphincter, bronchioles	smooth muscle contraction,
	isoprenaline	urinary bladder,	contraction,
		iris, blood vessels of erectile tissue,	smooth muscle relaxation,
		heart muscle,	positive ionotropic effect
		salivary gland,	increase in secretion,
		adipose tissue, liver	glycogenolysis and gluconeogenesis,
		sweat glands,	increase in secretion,
		kidneys	Na reabsorption
α2-adrenoceptor	epinephrine>	pancreas and	inhibition of insulin secretion,
	norepinephrine⋙		induction of glucagon release, and
	isoprenaline	gastrointestinal tract	contraction of sphincters
β1-adrenoceptor	isoprenaline>	heart,	increase cardiac output,
	Norepinephrine>	kidneys (juxtaglomerular cells),	increase renin release, and
	Epinephrine	adipose tissue	lipolysis
β2-adrenoceptor	isoprenaline>	Bronchi,	smooth muscle relaxation,
	epinephrine≫	urinary sphincter, bladder wall,	smooth muscle relaxation,
	norepinephrine	skeletal muscle,	dilate arteries
		adipose tissue, liver	glycogenolysis and gluconeogenesis,
		gastrointestinal tract,	contract sphincters,
		salivary glands,	thickened secretions,
		mast cells, and	inhibit histamine release, and
		kidneys (juxtaglomerular cells)	increase renin release
β3-adrenoceptor	isoprenaline> norepinephrine = epinephrine	adipose tissue	enhancement of lipolysis