TABLE 1.

Adrenergic receptors and physiological effects.

Subtypes	G proteins	Intracellular messengers	Target organs	Physiological effects
α1	Gq	Increase in PLC and IP3	Uterine	Contraction
			Vascular smooth muscles	Contraction
			Blood vessels	Constriction
			GI sphincter	Increase in tone
			Urinary sphincter	Increase in tone
			Pupillary radial muscle	Contraction (mydriasis)
			Pilomotor smooth muscle	Contracts (erects hair)
α2	Gi	Decrease in cAMP	Presynaptic nerves
			Adrenergic and cholinergic nerves terminals	Inhibit transmitter release
			Platelets	Stimulate aggregation
			Some vascular smooth muscle	Contraction
			Fat cells	Inhibit lipolysis
			Pancreatic B cells	Inhibit insuline release
			Ciliary epithelium	Reduction of humor secretion
β1	Gs	Increase in cAMP	Heart	Stimulates rate and force
			Kidney	Stimulates renin release
β2	Gs	Increase in cAMP	Liver	Stimulates glycogenolysis
			Pancreatic B cells	Stimulates insulin release
			Skeletal muscle	Contraction
			Heart	Stimulates rate and force
			Ciliary epithelium	Increases of humor secretion
			Airways, uterine and vascular smooth muscle	Relaxes
			Uterine	Inhibit contraction
β3	Gs	Increase in cAMP	Adipose tissues (Fat cells)	Stimulates lipolysis