Renal Electrolyte Regulation -- Answers

1. C. Blood flowing through the stenosis will encounter a high resistance, which will cause the pressure to drop on the downstream side of the stenotic area. This will lead to secretion of renin, which causes blood angiotensin II to increase, which will raise systemic arterial blood pressure and constrict the renal efferent arteriole. However, blood pressure in the glomerular capillaries will fall because of the drop in pressure as blood enters the glomerular vessels.

2. E. The ACE inhibitor will reduce angiotensin II concentration, so arterial blood pressure will drop, which reduce glomerular capillary hydrostatic pressure and filtration.

3. D.

4. C. Increase renin will eventually result in a rise in aldosterone, which increases Na-K pumping (antiport) in the renal distal tubule and collecting duct. Thus, Na reabsorption will increase (reduce excretion) and K secretion will increase (increase excretion).