What mechanism underlies renovascular hypertension?

Renovascular hypertension is primarily driven by the mechanism involving renal ischemia that stimulates the release of renin from the juxtaglomerular cells in the kidneys. When there is decreased blood flow or reduced perfusion pressure to the renal arteries, this ischemia triggers the kidneys to secrete renin. Renin acts on angiotensinogen, a protein produced by the liver, converting it into angiotensin I, which is subsequently converted to angiotensin II by the angiotensin-converting enzyme (ACE) primarily in the lungs.

Angiotensin II exerts several effects that contribute to hypertension, including promoting vasoconstriction, stimulating the adrenal glands to release aldosterone, and causing the kidneys to retain sodium and water, all of which increase blood pressure. Therefore, the underlying mechanism of renovascular hypertension is closely tied to this pathway of renin release in response to renal ischemia, making this answer the most accurate in describing the condition's etiology.

The other choices touch on aspects related to hypertension but do not specifically delineate the primary pathway involved in renovascular hypertension. For instance, increased blood volume due to fluid retention can contribute to hypertension in general but is not the distinctive mechanism in renovascular cases. Excessive secretion