Question

Endothelin acts through which second messenger / receptor pathway?

• A. cAMP
• B. cGMP
• C. Na+ receptors
• D. Calcium receptors

Hint:

Endothelin acting on endothelial receptors releases NO, which raises this cyclic nucleotide.

Answer 1

The Correct Option is B

Step 1: Endothelin-1 is the strongest natural vasoconstrictor and comes from endothelial cells, binding $ET_A$ and $ET_B$ G-protein coupled receptors.

Step 2: Through the endothelial $ET_B$ receptor it triggers nitric oxide release, and NO drives guanylate cyclase to generate cyclic GMP in the underlying smooth muscle.

Step 3: The expected answer here is therefore the cGMP pathway, which is listed as option B.

Step 4: The other choices (cAMP, sodium, or calcium receptors) do not represent this route, so they are excluded.

\[\boxed{\text{cGMP}}\]