Answer: Beta 2 (β2) has the greatest sensitivity for epinephrine or Adrenaline.
Step-by-step explanation:
β-receptors have the subtypes β1, β2, and β3.
Adrenaline (epinephrine) reacts with both α- and β-adrenoceptors, causing vasoconstriction and vasodilation, respectively. Although α receptors are less sensitive to epinephrine, when activated, they override the vasodilation mediated by β-adrenoceptors. The result is that high levels of circulating epinephrine cause vasoconstriction. At lower levels of circulating epinephrine, β-adrenoceptor stimulation dominates, producing an overall vasodilation.
Some effects of β2-Receptor on Adrenaline are as follows:
i. It smooth muscle relaxation, e.g., in bronchi and the GI tract (decreased motility).
ii. It causes lipolysis in adipose tissue.
iii. It causes anabolism in skeletal muscle.
iv. It dilates arteries to skeletal muscle.
v. It stimulates insulin secretion.
vi. It contracts the sphincters of the GI tract.
vii. It thickens secretions from the salivary glands.
viii. It increases renin secretion from the kidney.