MCAT Question A Day - 7/31/14 - Answer!
If a patient were administered a drug that selectively bound and inactivated renin, which of the following would most likely result?
A. The patient's blood pressure would increase.
B. Platelets would be found in the urine.
C. The amount of filtrate entering Bowman's capsule would increase.
D. Sodium reabsorption by the distal tubule would decrease.
D is correct. Renin secretion catalyzes the conversion of angiotensin I to angiotensin II, which increases the secretion of aldosterone. If renin is blocked, then aldosterone cannot cause increased synthesis of sodium absorbing proteins, and sodium absorption decreases. Without renin secretion, production of angiotensin II would decrease. Blood pressure would decrease, not increase; A is wrong. Platelets are irrelevant; B is wrong.
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D is correct. Renin secretion catalyzes the conversion of angiotensin I to angiotensin II, which increases the secretion of aldosterone. If renin is blocked, then aldosterone cannot cause increased synthesis of sodium absorbing proteins, and sodium absorption decreases. Without renin secretion, production of angiotensin II would decrease. Blood pressure would decrease, not increase; A is wrong. Platelets are irrelevant; B is wrong.
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