According to the myogenic hypothesis of renal autoregulation, the afferent arterioles contract in response to stretch induced by
**Core Concept**
The myogenic hypothesis of renal autoregulation proposes that changes in blood pressure cause afferent arterioles to contract or dilate in response to stretch, maintaining a relatively constant glomerular filtration rate (GFR) despite fluctuations in systemic blood pressure. This mechanism is crucial for maintaining renal function and preventing hypotension-induced renal damage.
**Why the Correct Answer is Right**
The myogenic response is mediated by the mechanoreceptors in the smooth muscle cells of the afferent arteriole, which sense the stretch and depolarize the muscle cells, leading to contraction. This contraction reduces the diameter of the arteriole and increases vascular resistance, thereby maintaining GFR during periods of increased blood pressure. The Rho-associated protein kinase (ROCK) pathway plays a crucial role in the myogenic response by regulating the contraction of smooth muscle cells.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not directly related to the myogenic hypothesis of renal autoregulation and does not explain the mechanism of afferent arteriole contraction.
**Option B:** This option is incorrect as the tubuloglomerular feedback mechanism is a separate regulatory mechanism that responds to changes in sodium delivery to the distal tubule, not stretch-induced contraction of afferent arterioles.
**Option C:** This option is incorrect as the juxtaglomerular apparatus is involved in the renin-angiotensin-aldosterone system, which responds to changes in blood pressure and electrolyte balance, but is not directly responsible for the myogenic response.
**Clinical Pearl / High-Yield Fact**
The myogenic hypothesis of renal autoregulation is an essential mechanism for maintaining renal function, particularly in conditions of hypertension or hypotension. Understanding this concept is crucial for managing patients with renal disease and preventing complications.
**Correct Answer:** C. Increased intraluminal pressure.