Figure 141

Pathophysiology of ischemic and toxic acute renal failure (ARF). The severe reduction in glomerular filtration rate (GFR) associated with established ischemic or toxic renal injury is due to the combined effects of alterations in intrarenal hemody-namics and tubular injury. The hemodynamic alterations associated with ARF include afferent arterio-lar constriction and mesangial contraction, both of which directly reduce GFR. Tubular injury reduces GFR by causing tubular obstruction and by allowing backleak of glomerular filtrate. Abnormalities in tubular reabsorption of solute may contribute to intrarenal vasoconstriction by activating the tubu-loglomerular (TG) feedback system. GPF—glomerular plasmaflow; P—glomerular pressure; Kf— glomerular ultrafiltration coefficient.

Angiotensin II Endothelin Thromboxane Adenosine Leukotrienes Platelet-activating factor

Angiotensin II Endothelin Thromboxane Adenosine Leukotrienes Platelet-activating factor

Ischemic or toxic injury to the kidney

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