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Acute ischemic renal failure: review of experimental studies on pathophysiology and potential protective
1Medizinische Poliklinik, University of Bonn, FRG.
Abstract:
More than 70% of acute renal failure in man is of circulatory nature and results from hypoxic injury to the kidney. Since intrarenal hemodynamic and metabolic events cannot be accurately assessed in human acute renal failure, various experimental models of renal hypoperfusion or complete interruption of renal blood supply, such as norepinephrine-induced acute renal failure or clamping of the renal artery, have been employed to obtain more direct insight into the pathophysiological events and consequences of hypoxia, although none of these models may truly mimic human acute renal failure. In addition, the severity of experimental acute renal failure, that is, oliguric or nonoliguric acute renal failure resulting from renal hypoperfusion, depends not only on the model employed but also largely on the experimental conditions. In the hemodynamic models a vascular component is incriminated in the initial phase, and persistent tubular tissue dysfunction in the maintenance phase of ischemic acute renal failure. Hypoxic vascular injury will lead to vasoconstriction; a decrease in glomerular filtration pressure, glomerular capillary surface area, and permeability; and thus to a decrease in glomerular filtration rate. In contrast to previous concepts which incriminated the renal cortex as the main target tissue of hypoxic injury, in recent years attention has been focused on impaired medullary perfusion as the most prominent pathophysiological event leading to the decrease in total renal blood flow and glomerular filtration rate. Medullary congestion may result from hypoxic cell swelling with vascular compression.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Acute renal failure, often caused by circulatory issues and kidney hypoxia, is studied using experimental models. Research highlights impaired medullary perfusion as a key factor in reduced kidney function.
Area of Science:
- Nephrology
- Pathophysiology
- Experimental Medicine
Background:
- Over 70% of human acute renal failure stems from circulatory problems, leading to hypoxic kidney injury.
- Direct assessment of intrarenal hemodynamics and metabolism in human acute renal failure is challenging.
- Experimental models are crucial for understanding the pathophysiology of renal hypoperfusion and hypoxia.
Purpose of the Study:
- To investigate the pathophysiological events and consequences of hypoxic injury in the kidney.
- To explore the role of intrarenal hemodynamics in acute renal failure.
- To identify the primary site of hypoxic injury in the kidney.
Main Methods:
- Utilizing experimental models of renal hypoperfusion and interrupted blood supply (e.g., norepinephrine-induced failure, renal artery clamping).
- Analyzing hemodynamic and vascular components in the initial phase of ischemic acute renal failure.
- Examining tubular tissue dysfunction during the maintenance phase.
Main Results:
- Hypoxic vascular injury causes vasoconstriction, reduced glomerular filtration pressure, surface area, and permeability, leading to decreased glomerular filtration rate.
- Recent findings emphasize impaired medullary perfusion over cortical injury as the primary cause of reduced renal blood flow and GFR.
- Medullary congestion, potentially from hypoxic cell swelling and vascular compression, is implicated.
Conclusions:
- Experimental models, while not perfectly mimicking human conditions, provide insight into acute renal failure mechanisms.
- Impaired medullary perfusion is a critical factor in the reduced renal function observed in ischemic acute renal failure.
- Understanding these mechanisms is vital for developing effective treatments for acute kidney injury.