What is the receptor effect pattern of epinephrine?

What is the receptor effect pattern of epinephrine?

• A. Alpha-only effect
• B. Dose-dependent alpha effect, stronger beta effects normally
• C. Pure beta effect
• D. No receptor effects

Answer: (B)

Epinephrine acts on both alpha and beta adrenergic receptors, and its effects change with the dose. At low doses, beta-adrenergic effects predominate, increasing heart rate and contractility (beta-1) and causing bronchodilation and some vasodilation (beta-2). As the dose rises, alpha-adrenergic effects (especially alpha-1–mediated vasoconstriction) become more pronounced, raising systemic vascular resistance and blood pressure. So the pattern is dose-dependent: alpha effects emerge with higher doses, but beta effects are normally stronger at lower doses. This makes the description of a dose-dependent alpha effect with beta effects normally stronger the best fit.

Epinephrine acts on both alpha and beta adrenergic receptors, and its effects change with the dose. At low doses, beta-adrenergic effects predominate, increasing heart rate and contractility (beta-1) and causing bronchodilation and some vasodilation (beta-2). As the dose rises, alpha-adrenergic effects (especially alpha-1–mediated vasoconstriction) become more pronounced, raising systemic vascular resistance and blood pressure. So the pattern is dose-dependent: alpha effects emerge with higher doses, but beta effects are normally stronger at lower doses. This makes the description of a dose-dependent alpha effect with beta effects normally stronger the best fit.