Adenosine is an effective treatment for cardiac arrhythmia. Adenosine does not i

Question

Adenosine is an effective treatment for cardiac arrhythmia. Adenosine does not increase [cAMP] when added alone to cardiac muscle cells & it doesn’t compete with epinephrine for binding to the -AR. Moreover, Adenosine reduces the amount of [cAMP] produced in cells treated with epinephrine when they are added together. Which of the following explains adenosine’s mechanism of action?

A. Adenosine binds to its own receptor and inhibits Gs.

B. Adenosine binds to its own receptor and activates Gi.

C. Adenosine is an epinephrine antagonist and does not activate Gs.

D. Adenosine is an epinephrine agonist and activates Gi.

E. Adenosine is an epinephrine antagonist and activates Gi.

Explanation / Answer

According to the given information, the adenosine does not compete with epinephrine for binding to the beta-AR. Thus, adenosine cannot be agonist or antagonist in action with reference to epinephrine.

Adenosine is a ubiquitous endogenous nucleoside that modulates functions of various organs and plays an important role in cardiovascular system. The adenosine receptors are typical G i-coupled receptors, which initiates signaling cascade.

Thu, the correct option among the following is B.

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