A 64-year-old guy arrives to the clinic after finding that his blood pressure is excessive at the dentist's office. The patient has always been "fit as a bull" and is a veteran of battle. He's had a number of minor surgeries for wounds from the conflict. He claims to have used alcohol and smoke for many years, but not just now. He mentions chest discomfort with effort after thorough inquiry. Both the blood pressure and the pulse are 155/90 mm Hg. Physical examination findings include a systolic bruit over the left carotid artery and a reduced pulse amplitude over the right femoral artery. The serum creatinine level is 1.1 mg/dL, and the resting ECG is unremarkable. Protein levels in urine are negative. Treatment for hypertension is initiated with ramipril. On a follow-up visit 3 weeks later, blood pressure is 142/85 mm Hg but serum creatinine has increased to 2 mg/dL. This laboratory finding is best explained by an effect of the drug on which of the following structures (as indicated in the image)?

Question

A 64-year-old guy arrives to the clinic after finding that his blood pressure is excessive at the dentist's office. The patient has always been "fit as a bull" and is a veteran of battle. He's had a number of minor surgeries for wounds from the conflict. He claims to have used alcohol and smoke for many years, but not just now. He mentions chest discomfort with effort after thorough inquiry. Both the blood pressure and the pulse are 155/90 mm Hg. Physical examination findings include a systolic bruit over the left carotid artery and a reduced pulse amplitude over the right femoral artery. The serum creatinine level is 1.1 mg/dL, and the resting ECG is unremarkable. Protein levels in urine are negative. Treatment for hypertension is initiated with ramipril.  On a follow-up visit 3 weeks later, blood pressure is 142/85 mm Hg but serum creatinine has increased to 2 mg/dL.  This laboratory finding is best explained by an effect of the drug on which of the following structures (as indicated in the image)?

Quizplus · Accepted Answer

Eductional Objective: The glomerular filtration pressure and rate are decreased by ACE inhibitors because they lower angiotensin II levels and widen efferent arterioles. Patients who already have low intrarenal perfusion pressure may develop acute renal failure as a result of this (eg, renal artery stenosis, congestive heart failure, hypovolemia).

A 64-Year-Old Guy Arrives to the Clinic After Finding That