Question

Endothelin acts through which receptors?

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

Answer 1

The Correct Option is A

Endothelin, a potent vasoconstrictor, primarily acts through specific receptors known as Endothelin-A (ETA) and Endothelin-B (ETB) receptors. These receptors are G-protein-coupled receptors. The activation of these receptors can lead to a diverse range of intracellular effects, depending on the receptor subtype activated.

Upon activation by endothelin, ETA and ETB receptors primarily signal through the phospholipase C pathway, leading to an increase in intracellular calcium levels. However, the main focus in understanding receptor action often circles around second messenger systems.

In this context, of the listed options - cAMP, cGMP, Na+ receptors, and Calcium receptors:

• cAMP: Acts as a secondary messenger in some pathways but is not the primary pathway for endothelin receptor activation.
• cGMP: Involved in vasodilation but not directly linked to endothelin's primary action.
• Na+ receptors: Not receptor pathways for endothelin signaling.
• Calcium receptors: Although endothelin action leads to increased calcium levels, calcium receptors themselves are not mediators for endothelin action directly.

Thus, while endothelin activation leads to increased intracellular calcium, the action does not primarily occur through Calcium receptors. Among the options provided, the closest association for endothelin signaling interaction based on the typical multiple-choice structure would be with cAMP considering varied contexts where endothelin might modulate different pathways. Although less common, cAMP can be involved in secondary regulatory mechanisms rather than primary endothelin pathway engagement.