Image Based Question – 74248

A pharmacological experiment acted to study effect of three drugs on heart rate and blood pressure. The following graphs were obtained before and after giving the drug. Which of the following statements is correct?

A. A is isoprenaline

B. B is epinephrine

C. C is norepinephrine

D. Action of C is antagonized by muscarinic blockers

Correct Answer » B Explanation

Ans: B. B is epinephrine

(Ref Goodman Gilman 12/e p277, 283; KDT 7/e p130-131)

According to graph ,

• A: Norepinephrine, B: Adrenaline, C: Isoproterenol.
• Action of Isoproterenol is blocked by beta-blockers and not by muscarinic blockers.

Epinephrine:

• One of most potent vasopressor drugs.

Rapid IV infusion of pharmacological dose:

• Dose-dependent increase in BP.

MOA:

Direct myocardial stimulation by,

• Increases ventricular contraction strength (positive inotropic action).
• Increased heart rate (positive chronotropic action).