A 34-year-old woman has recurrent throbbing headaches that occur several times a month and cause significant distress. They are accompanied by nausea and photophobia. She has had 5 emergency department visits for these headaches over the last 6 months. During office visits, her blood pressure ranges from 140/90 mm Hg to 150/95 mm Hg. Neurologic examination is unremarkable. The patient is prescribed metoprolol and is advised that the medication is expected to decrease the frequency of headaches and also lower blood pressure in the long term. Which of the following best explains this medication's effect on blood pressure?

Question

A 34-year-old woman has recurrent throbbing headaches that occur several times a month and cause significant distress.  They are accompanied by nausea and photophobia.  She has had 5 emergency department visits for these headaches over the last 6 months.  During office visits, her blood pressure ranges from 140/90 mm Hg to 150/95 mm Hg.  Neurologic examination is unremarkable.  The patient is prescribed metoprolol and is advised that the medication is expected to decrease the frequency of headaches and also lower blood pressure in the long term.  Which of the following best explains this medication's effect on blood pressure?

Quizplus · Accepted Answer

11ec160b_3b9b_a50f_9249_1b19a99aeed3_MD0001_00 Beta blockers are useful for treating hypertensive patients with comorbid conditions such as migraine, essential tremor, angina pectoris/prior myocardial infarction, and atrial fibrillation. Beta blockers lower blood pressure via 2 mechanisms: Renin release is mediated in part through sympathetic stimulation of beta-1 receptors located on juxtaglomerular cells. Therefore, beta-adrenergic blocking drugs (eg, metoprolol) act to inhibit renin release, which in turn reduces the conversion of angiotensinogen to angiotensin I and reduces the levels of angiotensin II (a potent vasoconstrictor) and aldosterone (decreasing renal sodium and water retention) (Choice D). (Choice A) Beta blockers block the action of endogenous catecholamines on adrenergic beta receptors but have no significant effect on circulating levels of catecholamine. (Choice C) Beta-adrenergic receptor antagonists depress conduction through the atrioventricular (AV) node and can cause varying degrees of AV block. (Choice E) Long-term use of beta blockers will cause either no change or modest decreases in the peripheral vascular resistance due to their effects on the renin-angiotensin-aldosterone system. Educational objective: Beta blockers inhibit release of renin from renal juxtaglomerular cells through antagonism of beta-1 receptors on these cells. Inhibition of renin release prevents activation of the renin-angiotensin-aldosterone pathway, which results in decreased vasoconstriction and decreased renal sodium and water retention. __________ References: Beta-adrenergic receptor blockade as a therapeutic approach for suppressing the renin-angiotensin-aldosterone system in normotensive and hypertensive subjects. (http://www.ncbi.nlm.nih.gov/pubmed/10342782)

A 34-Year-Old Woman Has Recurrent Throbbing Headaches That Occur Several