What is the primary action of epinephrine on most target tissues?

What is the primary action of epinephrine on most target tissues?

• A. It inhibits glycogenolysis.
• B. It stimulates glycogenolysis, lipolysis, increases heart rate and contractility.
• C. It suppresses sympathetic activity.
• D. It increases insulin secretion.

Answer: (B)

Epinephrine’s main action on most target tissues is to mobilize energy and boost cardiac performance during sympathetic activation. It triggers glycogenolysis in the liver (and to some extent in muscle) to raise blood glucose and promotes lipolysis in adipose tissue to release fatty acids for fuel. At the same time, it increases heart rate and the force of contraction, enhancing blood flow to muscles. It also tends to suppress insulin secretion to keep glucose available in the bloodstream for quick use. The other statements don’t fit because epinephrine does the opposite: it stimulates glycogen breakdown rather than inhibits it, it is a hormone of the sympathetic system rather than suppressing it, and it typically reduces insulin release rather than increasing it.

Epinephrine’s main action on most target tissues is to mobilize energy and boost cardiac performance during sympathetic activation. It triggers glycogenolysis in the liver (and to some extent in muscle) to raise blood glucose and promotes lipolysis in adipose tissue to release fatty acids for fuel. At the same time, it increases heart rate and the force of contraction, enhancing blood flow to muscles. It also tends to suppress insulin secretion to keep glucose available in the bloodstream for quick use. The other statements don’t fit because epinephrine does the opposite: it stimulates glycogen breakdown rather than inhibits it, it is a hormone of the sympathetic system rather than suppressing it, and it typically reduces insulin release rather than increasing it.