Question 1

A 63-year-old man is experiencing an acute exacerbation of his congestive heart failure in the intensive care unit. Among other treatments, the physicians have decided to start a drug infusion that will increase the contractility of his heart while having a minimal effect on his systemic vascular resistance. Which of the following would be the best option?

A) Epinephrine
B) Dobutamine
C) Isoproteronol
D) Norepinephrine
E) Phenylephrine

Dobutamine

Accepted Answer

Dobutamine is a selective beta-1 adrenergic receptor agonist that increases cardiac contractility. Its effects on systemic vascular resistance (SVR) are less pronounced than the other options. Phenylephrine and norepinephrine both increase SVR via alpha-1 adrenergic receptor agonism. Isoproteronol decreases SVR via beta-2 agonism. Epinephrine has variable effects on SVR due to both alpha-1-mediated vasoconstriction and beta-2-mediated vasodilatation.

Question 2

Norepinephrine is the neurotransmitter secreted by postganglionic sympathetic neurons EXCEPT FOR those that innervate:&#10;A) Sweat glands&#10;B) Heart&#10;C) Blood vessels&#10;D) Pupils&#10;E) Pancreas

Accepted Answer

Sweat glands are supplied by the sympathetic nervous system. However, the postganglionic neurons secrete acetylcholine, which activates the sweat glands' muscarinic receptors.

Question 3

A 67-year-old man who suffers from hypertension and benign prostatic hyperplasia (BPH) has been receiving medications for both of those conditions. During his routine checkup, he tells his physician that he has experienced frequent episodes of light-headedness upon standing up. Which of the following medications is most likely responsible for these episodes?

A) Metoprolol
B) Propranolol
C) Ephedrine
D) Clonidine
E) Terazosin

Terazosin

Accepted Answer

Terazosin is an alpha-1 adrenergic receptor antagonist that reduces symptoms of BPH. However, it is not entirely selective for the prostate. Alpha-1 blockade induces vasodilatation and orthostatic hypotension.

Deck 11: Drugs Affecting the Sympathetic Nervous System