Multiple choice questions
1. Presynaptic blockade of alpha-2 adrenergic receptors increases the release of norepinephrine
a.
What are two major cardiovascular actions of competitive alpha-adrenergic
antagonists?
b.
What receptors are inhibited by phentolamine (Regitine)?
c.
How does alpha-2 receptor blockade of sympathetic nerve terminals by an alpha
adrenergic antagonist such as phentolamine alter release of norepinephrine?
d.
How does phentolamine produce tachycardia?
2. Tachycardia reflects release of norepinephrine from sympathetic postganglionic nerve terminals
owing to alpha-2 receptor blockade.
.
Which autonomic drugs produce bronchoconstriction?
a.
List five side-effects of beta-blockers.
b.
How does phentolamine produce tachycardia?
c.
What is a sympatholytic?
3. Phentolamine produces peripheral vasodilation and a decrease in blood pressure. This action
occurs because phentolamine produces a moderately effective competitive alpha adrenergic
receptor blockade that is relatively transient
.
What is the major pharmacologic action of phentolamine (Regitine)? How is this effect
accomplished?
a.
Which autonomic drugs produce bronchoconstriction?
b.
What receptors are inhibited by phentolamine (Regitine)?
c.
What are two major cardiovascular actions of competitive alpha-adrenergic
antagonists?
4. The cardiac beta receptors are up regulated as a result of chronic beta blockade and are highly
sensitive to catecholamines
.
List five side-effects of beta-blockers.
a.
What receptors are inhibited by phentolamine (Regitine)?
b.
You would avoid administering labetalol to patients with what disorders?
c.
Why do tachycardia and hypertension develop after abrupt withdrawal of a beta
blocker?
5. Propranolol is a nonselective competitive antagonist of beta-adrenergic receptors. Blockade of
beta-2 receptors can promote bronchospasm. Blockade of beta-1 receptors decreases heart
rate and contractility.
.
What receptors are inhibited by phentolamine (Regitine)?
a.
What is the purpose of giving a beta blocker such as propranolol to anginal patients?
b.
Propranolol works on what receptors? How does propranolol affect the airway and the
heart?
c.
What kind of drugs are phenoxybenzamine and prazosin, and how are they used in
anesthesia?
5 True/False questions
1. What is a sympatholytic? → Side effects of beta-blockers include: (1) heart block (depressed
conduction through the atrioventricular node), (2) worsening of congestive heart failure, (3)
bronchospasm (beta-2 receptor blockade), (4) coronary artery constriction, and (5) inhibition of
insulin release
True
False
2. What are two major cardiovascular actions of competitive alpha-adrenergic
antagonists? → Tachycardia, hypertension, and possibly angina
True
False
3. In addition to its use in the preoperative preparation of the patient with pheochromocytoma,
physicians use prazosin to treat essential hypertension and to decrease afterload in patients
with congestive heart failure. Why is prazosin a better choice for
treating patients than a non-selective alpha
receptor antagonist? → Prazosin produces vasodilation by postsynaptic alpha-1 antagonism
w/o increasing the release of norepinephrine from sympathetic postganglionic nerve terminals.
Non-selective alpha antagonists produce vasodilation (alpha-1 blockade) but also increase the
release of norepinephrine from sympathetic nerve terminals (presynaptic alpha-2 blockade).
Prazosin is less likely than non-selective alpha-blocker to evoke tachycardia, secondary to
increased release of norepinephrine
from sympathetic postganglionic nerve terminals at the sinoatrial
node (a presynaptic alpha-2 antagonistic action).
True
False
4. What are three manifestations of abrupt withdrawal of beta adrenergic receptor
antagonists? → Decreased blood pressure secondary to vasodilation. There may also be reflex
tachycardia.
True
False
5. What drugs are not appropriate for treating supraventricular tachycardia in the patient with
bronchospastic disease? Why? → Tachycardia reflects release of norepinephrine from
sympathetic postganglionic nerve terminals owing to alpha-2 receptor blockade.
True
False