According to myogenic hypothesis of renal autoregulation the afferent aerioles contract in response to stretch-induced by
**Core Concept**
The myogenic hypothesis of renal autoregulation proposes that afferent arterioles constrict in response to increased blood pressure and stretch, thus maintaining a relatively constant glomerular filtration rate (GFR) despite fluctuations in systemic blood pressure. This mechanism is crucial for maintaining renal function and preventing damage from excessive pressure.
**Why the Correct Answer is Right**
The myogenic hypothesis is mediated by the mechanoreceptors in the afferent arteriole wall, which sense the stretch-induced by increased blood pressure. This triggers a cascade of signaling events, ultimately leading to the contraction of smooth muscle cells in the arteriole wall. The key players involved in this process include the stretch-activated ion channels, such as TRPV4 and Piezo1, which are activated by mechanical stress, and the subsequent increase in intracellular calcium levels, which triggers muscle contraction. The Rho kinase pathway also plays a crucial role in mediating the vasoconstrictive response.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is likely a distractor, as the myogenic hypothesis does not involve the release of a specific neurotransmitter or hormone in response to stretch-induced by increased blood pressure.
* **Option B:** This option is incorrect, as the tubuloglomerular feedback mechanism, which is another important regulator of renal autoregulation, involves the sensing of sodium chloride levels in the distal tubule, not stretch-induced by increased blood pressure.
* **Option D:** This option is also incorrect, as the juxtaglomerular apparatus, which is involved in the renin-angiotensin-aldosterone system, senses changes in blood pressure 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 mechanism is crucial for managing patients with renal disease or hypertension.
**Correct Answer:** C. Increased blood pressure.