What physiological effect occurs due to decreased dietary salt intake in renal physiology?

When dietary salt intake decreases, the body responds by activating several physiological mechanisms to maintain sodium balance and blood pressure. One of these responses involves the renin-angiotensin-aldosterone system (RAAS).

With lower sodium levels detected in the renal tubules, the juxtaglomerular cells in the kidney sense the decreased sodium concentration and subsequently increase the secretion of renin. Renin then catalyzes the conversion of angiotensinogen, produced by the liver, into angiotensin I, which is then converted to angiotensin II by angiotensin-converting enzyme (ACE) primarily in the lungs. Angiotensin II plays several roles, one of which is to stimulate the adrenal cortex to increase the secretion of aldosterone.

Aldosterone acts on the kidneys, specifically on the distal convoluted tubules and collecting ducts, leading to increased reabsorption of sodium back into the bloodstream. This reabsorption of sodium is accompanied by water retention, which helps to increase blood volume and blood pressure. However, the direct consequence of decreased dietary salt intake is the increased activity of aldosterone, which ensures that the body retains sodium despite the low intake.

Therefore, the correct answer reflects that decreased dietary salt intake leads to