TABLE 9.1 Responses to Adrenergic and Cholinergic Nerve Stimulation
Organ or Tissue Function
Adrenoceptor Type Adrenergic Response
Rate (chronotropic effect) Contractile force (inotropic effect) Conduction velocity (dromotropic effect)
Bronchial smooth muscle Blood vessels (arteries and arterioles)' Cutaneous Visceral Pulmonary Skeletal muscle Coronary Cerebral Veins
Gastrointestinal tract (tone, motility, and secretory activity) Sphincters Splenic capsule Urinary bladder Detrusor muscle Trigone-sphincter muscle Uterus
Glycogenolysis Skeletal muscle Liver Lipolysis Renin secretion Insulin secretion
Increase Increase Increase
Constriction of radial muscle causing dilation (mydriasis) No innervation
Increase Increase Increase Increase Decrease
Contraction of circular muscle (miosis) Contraction of ciliary muscle producing accommodation for near vision Contraction
No innervation6 No innervation6 No innervation6 No innervation6 No innervation6
No innervation Increase
Relaxation No innervation
None None None None Increase
"Muscarinic cholinoceptors. See Chapter 12 for a discussion of subtypes.
There are some p2-receptors in the heart. The ratio of p1 to p2 varies with the region and the species. In the human heart, the ratio of p1 to p2
is about 3:2 in atria and 4:1 in ventricles.
There are some a2-receptors in some vascular smooth muscle.
"Tow doses of epinephrine of endogenous or exogenous origin plus other p2-receptor agonists dilate these blood vessels.
6Exogenously administered cholinergic drugs dilate these blood vessels. ^Dilation is the dominant in vivo response, owing to indirect effects.
^-Adrenoceptors may be involved in hypersecretory responses.
'Responses depend on hormonal state.
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