Catecholamine Physiology
This enzyme metabolizes catecholamines primarily in the liver and GI tract.
What is catechol-O-methyltransferase (COMT)?
This drug is considered an almost pure α-agonist.
What is phenylephrine?
This α-blocker causes irreversible receptor binding.
What is phenoxybenzamine?
This direct vasodilator primarily reduces preload by venodilation.
What is nitroglycerin (NTG)?
The two primary mechanisms responsible for ectopic cardiac arrhythmias are these.
What are reentry and enhanced automaticity?
The final urinary metabolite of epinephrine and norepinephrine is this compound.
What is vanillylmandelic acid (VMA)?
Compared to epinephrine, this agent has minimal β2 activity and greater increases in SVR.
What is norepinephrine?
Blockade of presynaptic α2 receptors produces this physiologic effect.
What is increased norepinephrine release?
This drug causes balanced arterial and venous vasodilation and acts via nitric oxide release.
What is sodium nitroprusside (NTP)?
This acid–base disturbance is more arrhythmogenic than acidosis.
What is alkalosis?
Stimulation of β2 receptors causes potassium to shift in this direction.
What is into the cell?
This phosphodiesterase inhibitor increases cardiac output by increasing cAMP.
What is milrinone?
This α-blocker is most associated with orthostatic hypotension.
What is phenoxybenzamine?
This vasodilator is commonly used for hypertensive emergencies in pregnancy and causes reflex tachycardia.
What is hydralazine?
Hypokalemia predisposes patients to arrhythmias by affecting this phase of the cardiac action potential.
What is repolarization (phase 3)?
This physiologic effect explains epinephrine-induced perioperative hyperglycemia.
What is increased glycogenolysis with inhibition of insulin release?
This drug increases cardiac output while being least likely to cause tachycardia.
What is milrinone?
This β-blocker also possesses significant α1-blocking activity.
What is labetalol?
This toxic metabolite limits prolonged or high-dose use of nitroprusside, especially in renal failure.
What is cyanide?
This class of antiarrhythmics prolongs the QT interval by blocking potassium channels.
What is Class III?
This receptor subtype is responsible for renin release from the kidney.
What is the β1 receptor?
At infusion rates of 3–10 mcg/kg/min, dopamine primarily stimulates this receptor in the heart.
What is the β1 receptor?
The IV β:α blocking ratio of labetalol is approximately this value.
What is 7:1?
This physiologic effect explains why nitroglycerin can worsen oxygenation in patients with pulmonary disease.
What is inhibition of hypoxic pulmonary vasoconstriction leading to V/Q mismatch?
Bradycardia predisposes to ventricular arrhythmias by causing this electrophysiologic phenomenon.
What is dispersion of refractory periods?