Question

Which of the following statements that suits best for adrenaline?

• A. \( \text{It is a selective } \alpha1\text{- adrenergic receptor agonist} \)
• B. \( \text{It is a selective } \alpha2\text{- adrenergic receptor agonist} \)
• C. \( \text{It is a selective } \beta3\text{- adrenergic receptor agonist} \)
• D. \( \text{It is a nonselective (}\beta1 \text{and } \beta2\text{) adrenergic receptor agonist} \)

Hint:

Think of adrenaline's widespread "fight or flight" response – it affects various organs through different adrenergic receptors, indicating non-selectivity.

Answer 1

The Correct Option is D

Adrenaline (epinephrine) is a catecholamine hormone and neurotransmitter that acts as a nonselective agonist on all adrenergic receptors, including $\alpha_1$, $\alpha_2$, $\beta_1$, $\beta_2$, and to some extent $\beta_3$. However, its prominent and clinically significant actions are mediated through its agonistic activity at $\alpha$ and $\beta$ (specifically $\beta_1$ and $\beta_2$) adrenergic receptors. While it does have some affinity for $\beta_3$ receptors, its primary classification in terms of its broad effects is as a nonselective adrenergic agonist. The provided correct answer focuses on its well-established non-selectivity for $\beta_1$ and $\beta_2$ receptors, which are crucial for its cardiovascular and bronchodilatory effects.