Autoregulation of renal blood flow

Explain how the myogenic mechanism and tubuloglomerular feedback are responsible for autoregulation of renal blood flow... 

The factors involved in regulation of GFR are listed in Table 45-3. Autoregulation of renal blood flow and GFR is widely thought to be explained by the myogenic theory. This theory is based on the principle that an increase in the wall tension of the afferent arterioles, brought about by an increase in perfusion pressure, causes automatic contraction of the arteriolar smooth muscle, thus increasing resistance and beeping the flow constant despite the increase in perfusion pressure. 

Zou, A.P., J.D. Imig, M. Kaldunski, P.R. Ortiz de Montellano, Z. Sui, and R.J Roman (1994). Inhibition of renal vascular 20-HETE production impairs autoregulation of renal blood flow. Am. J. Physiol. 266, F275-282. 

Herbaczynska-Cedro, K., Vane, J. R., 1973 Contribution of intrarenal generation of prostaglandin to autoregulation of renal blood flow in the dog. Circ. Res. 33, 428-436. 

A Dynamic Model of Renal Blood Flow Autoregulation, Bull. Math. Biol. 56, 411-430 (1994). 

Depending on the concentration, volatile anesthetics decrease the glomerular filtration rate and renal blood flow, and increase the filtration fraction. Since renal blood flow decreases during general anesthesia in spite of well-maintained or even increased perfusion pressures (due to increased renal vascular resistance), autoregulation of renal flow may be impaired by these drugs. 

Captopril is the fastest of the oral ACE inhibitors. It can also be used sublingually in patients who cannot swallow. Captopril shifts the entire curve of cerebral autoregulation in such a way that cerebral blood flow is maintained as the systemic pressure falls. Caution is needed in patients with significant renal... 

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