Question

What is the correct answer to the question below and why. Also, why is my answer (marked with a dash through it) wrong.

x6. Smooth muscle of arterioles is populated with alpha-1 subtype adrenergic receptors ivation of alpha-1 receptors leads to vasoconstriction. Both epinephrine and norepinephrine can activate alpha-1 receptors, however norepinephrine has considerably higher affinity for the receptor, compared to epinephrine. If we used to the figure to the right to explain this, we would say that 100 A. curve I is the higher affinity relationship, therefore it represents epinephrine binding, while curve II represents norepinephrine binding B. curve II is the higher affinity relationship, therefore it represents norepinephrine binding, while curve I represents epinephrine binding C. curve I is the lower affinity relationship, therefore it represents epinephrine binding, while curve Il represents norepinephrine binding D. curve II is the lower affinity relationship, therefore it represents epinephrine binding, while curve I represents norepinephrine binding E. none of the above Coneentraltion of messenger M

Answer 1

D) curve 2 is the lower affinity relationships, therefore it represents epinephrine binding, while curve 1 represents norepinephrine binding.

In the question it is mentioned that norepinephrine has higher affinity for the receptor and in the graph for curve 1 , we can clearly see that at lower concentration of messenger the percentage of receptor blocked is more, meaning it has higher affinity, so it is clearly norepinephrine.

You have marked option (A) which is wrong because curve 1 is norepinephrine not epinephrine, as it is mentioned in question that norepinephrine has higher affinity.