The nurse is administering the angiotensin II receptor antagonist valsartan. Which physiological response causes its therapeutic effect?

Rationale: A. Diuresis: While valsartan may indirectly promote mild diuresis by reducing aldosterone secretion, this is not its primary therapeutic mechanism. The main benefit comes from lowering vascular resistance rather than directly increasing urine output. B. Sympatholytic action: Valsartan does not work by inhibiting sympathetic nervous system activity. Instead, it specifically blocks angiotensin II receptors, which reduces vasoconstriction and aldosterone-mediated effects without directly altering sympathetic tone. C. Vasodilation: Valsartan blocks the binding of angiotensin II to AT1 receptors, preventing vasoconstriction and promoting vasodilation. This lowers systemic vascular resistance, decreases blood pressure, and improves cardiac workload. D. Chronotropic effect: A chronotropic effect alters heart rate, but valsartan does not directly affect the sinoatrial node or cardiac conduction. Its blood pressure-lowering benefit comes from vasodilation and reduced afterload, not changes in heart rate.