A 58-year-old man from rural Maharashtra presents with a 6-month history of progressive fatigue, muscle weakness, and polyuria. On examination, blood pressure is 165/105 mmHg. Laboratory investigations reveal: serum sodium 152 mEq/L, serum potassium 2.8 mEq/L, serum bicarbonate 30 mEq/L, and plasma renin activity is suppressed at 0.3 ng/mL/hr (normal 0.5–1.6). Plasma aldosterone is markedly elevated at 28 ng/dL (normal 4–31, but inappropriately high for the sodium level). Abdominal CT shows a 2 cm left adrenal nodule. Which mechanism best explains the suppressed renin activity in this patient?