This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
[{'content': 'According to myogenic hypothesis of renal  autoregulation,  the  afferent  arterioles contract in response to stretch induced by \nSelect and explain. \nA. NO release, B. Noradrenaline release, C. Opening of Ca2+  channels, D. Adenosine release', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Stretch\xa0on\xa0smooth\xa0muscle\xa0(afferent\xa0 arterioles)\xa0opens\xa0Ca+ channel, which\xa0causes contraction of afferent arterioles.the medullary interstitium.\nREGULATION OF GFR\nRegulation is done by:\n\nBlood pressure: Autoregulation\nResistance of afferent and efferent anterioles\n\n- Autoregulation: Constant maintenance of renal blood flow or, GFR over the span of renal perfusion pressure (pressure in renal artery minus pressure in renal vein ) from 80 to about 170mm Hg\n- Mechanism of autoregulation:\ni) Myogenic mechanism- contraction or relaxation of anteriolar smooth muscle in response to changes in vascular pressures; mediated by Ca++\nii) Tubule glomerular feedback (TGF) mechanism-mediated by macula densa cells (described later)', 'role': 'assistant'}]