Which observation suggested to Sutherland the involvement of a second messenger in epinephrine's effect on liver cells?
A) Enzymatic activity was proportional to the amount of calcium added to a cell-free extract.
B) Receptor studies indicated that epinephrine was a ligand.
C) Glycogen breakdown was observed only when epinephrine was administered to intact cells.
D) Glycogen breakdown was observed when epinephrine and glycogen phosphorylase were combined.
E) Epinephrine was known to have different effects on different types of cells.

Question

Quizplus · Accepted Answer

Sutherland observed that glycogen breakdown was observed only when epinephrine was administered to intact cells, suggesting that a second messenger was involved in transmitting the signal from the receptor to the glycogen phosphorylase enzyme. This observation led to the discovery of cyclic AMP as the second messenger for epinephrine in liver cells. Choices A, B, D, and E are not related to Sutherland's observation of a second messenger.

Which Observation Suggested to Sutherland the Involvement of a Second