What does Nor-epinephrine do to smooth muscle?

Answer 1

That depends entirely upon the receptor that norepinephrine activates.

1. alpha-1 receptors will induce smooth muscle contraction in response to norepinephrine. This is seen in blood vessels, splenic capsule, the uterus, the prostate, the radial muslces of the iris, the trigone of the bladder, the ureters, hair folicles, nasal secretion and metaarteriolar sphincter tone, salavary gland secretion, & sweat gland secretion.
2. alpha-2 receptors will act to inhibit smooth muscle contraction in response to norepinephrine. This is seen in the smooth muscle of the gastrointestinal tract.
3. beta-1 receptors stimulation by norepinephrine results in cardiac muscle (myocardium) contraction when stimulated by norepinephrine. This activity is seen in the heart; however, these receptors are also noted in the kidney with renin secretion.
4. beta-2 receptors will relax smooth muscle with activated by norepinephrine. This is seen with bronchial dilation, cilliary muscle dilation in the eye, detrussor muscle relaxation, blood vessel dilation, & uterine dilation.