Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0920646 (renal ischemia)
 2,515 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the pase decade, several experimental models of acute renal failure (ARF) have been evaluated with micropuncture and hemodynamic techniques. Five of these models have been most extensively studied: glycerol injection, renal artery clamping, intrarenal norepinephrine infusion, uranyl nitrate, and mercuric chloride administration. In the first three models, renal ischemia is the initiating insult, whereas in the two nephrotoxic models a direct effect of the agent on cellular integrity is also seemingly operative. In all of these models, renal blood flow 24--48 h after the initial insult either spontaneously returns to normal or can be elevated to this level with volume expansion but without restoration of the glomerular filtration rate. Therefore, the maintenance of ARF in these various models is due to other factors, which include tubular obstruction, leakage of filtrate across damaged tubular epithelium, and a decrease in the glomerular capillary ultrafiltration coefficient. In a given model, one or all three of these alterations may be present. Although these various models may not be completely analogous to the clinical setting, they have provided powerful tools for the study of ARF and their use has greatly increased our knowledge in this field.
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PMID:Current concepts on the pathophysiology of acute renal failure. 34 2

Ten rabbits with transparent ear chambers were grafted with small pieces of kidney. The resulting vessel anastomosis and restoration of renal blood flow allowed continuous microscopic observations of functioning renal tissue in vivo. When the grafts were well established, acute renal failure was induced in the rabbit by glycerol injection. All cases showed similar changes. Within minutes the brisk blood flow within the renal grafts became progressively more sluggish until complete stasis was established. The initial change was a blanching of intertubular and glomerular capillaries with progressive dilation and stasis of renal veins. Only after almost complete cessation of blood flow in most graft vessels, generally after a further 10 minutes, was any change in arteries or arterioles observed. The afferent arterioles and then larger arteries showed constriction followed by complete stasis. The ear chamber vessels (nonrenal) continued to flow normally. Blood flow was slowly re-established in the grafts and by the next day was normal in the surviving rabbits. These studies provided visual in vivo evidence that the mechanism of glycerol-induced acute renal failure is mediated by a reversible renal ischemia and that the factors responsible act particularly on renal vasculature. However, the mechanism whereby blood flow ceases is obscure and it cannot be attributed to arterial or arteriolar constriction.
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PMID:The mechanism of glycerol-induced acute renal failure. 77 14

The effects of intramuscular glycerol on ischemic acute renal failure was investigated in dogs. Anesthetized dogs received a bilateral 120-min renal artery obstruction (RAO) alone, RAO plus 5 ml/kg of 50% glycerol or RAO plus 5 ml/kg of 75% glycerol. Control groups received the glycerol injection, but not RAO. Renal histopathology was minimal in dogs receiving glycerol alone. In RAO dogs, those receiving 50% glycerol showed diffuse acute tubular necrosis (ATN), while those receiving 75% glycerol had severe ATN with extreme mortality. Changes in serum creatinine, creatinine clearance, and fractional excretion of sodium were consistent with the histopathologic changes. We conclude that myoglobinuria, of a degree insufficient to cause renal failure itself, can interact with renal ischemia to significantly exacerbate the renal damage produced.
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PMID:Myoglobinuria exacerbates ischemic renal damage in the dog. 279 46

In ischemic acute renal failure oxygen free radicals may mediate injury. In addition, iron appears to play a critical role in hydroxyl radical formation and lipid peroxidation during reperfusion of ischemic kidneys. To determine whether iron may play a similar role in pigment (heme protein)-induced acute renal failure, we studied the effects of the iron chelator deferoxamine in two experimental models of pigment-induced acute renal failure, intramuscular glycerol injection and intravenous hemoglobin infusion without and with concurrent ischemia in the rat. Intramuscular injection of 50% glycerol (5 ml/kg) caused inulin clearance to fall to 0.13 +/- 0.03 (SE) ml/min (normal value, 1.0-1.2 ml/min). Continuous infusion of deferoxamine beginning at the time of glycerol injection significantly attenuated this renal dysfunction. Deferoxamine-treated animals had an inulin clearance of 0.37 +/- 0.06 ml/min (P less than 0.01). Glycerol injection was also associated with significant lipid peroxidation, measured as renal malondialdehyde content. Deferoxamine-treated glycerol-injected rats had renal malondialdehyde content not significantly different from control animals. In another model of heme pigment-induced renal injury, hemoglobin was infused to produce hemoglobinuria. Inulin clearance 1 h after hemoglobin infusion was significantly reduced to 0.84 +/- 0.5 ml/min (P less than 0.025). Infusion of deferoxamine after hemoglobin prevented the hemoglobin-induced decrease in inulin clearance. Thirty minutes of renal ischemia followed by infusion of hemoglobin resulted in more severe renal dysfunction with inulin clearance of 0.54 +/- 0.08 ml/min. Deferoxamine infused at the time of reperfusion attenuated the fall in glomerular filtration rate after ischemia and hemoglobin infusion:inulin clearance 1.04 +/- 0.07 (P less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Hemoglobin- and myoglobin-induced acute renal failure in rats: role of iron in nephrotoxicity. 341 10

The role of volume depletion and renal ischemia in the development of renal functional impairment in glycerol-induced ARF is not clear. This study was designed to evaluate the role of volume depletion in this model by determining the hemodynamic and functional alterations which occur between 3 and 18 hr after glycerol administration and the reversibility of these changes in response to Ringer loading. Three hours after glycerol, Cln and RBF, measured by flowmeter, were reduced 70% and 52%, respectively, in comparison with control values. FeNa was 0.04%. Ringer loading increased Clkn to 103% and RBF to 93% of control values. Qualitatively similar results were found 6 hr after glycerol. At 18 hr, Cln and RBF were 47% of control values. After Ringer loading, RBF rose to 100% of control. The response of Cln, however, was a function of the baseline FeNa. Cln incrased substantijally in rats with low FeNa but changed only slightly in animals in which this parameter was increased. These studies indicate that the early reduction in the Cln is dependent upon the fall in RBF. At 12 and 18 hr, however, the fall in Cln is not blood flow-dependent, and a second mechanism must be operative. FeNa seems to be a reliable index of the functional status of a given animal.
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PMID:Sequential studies on the pathophysiology of glycerol-induced acute renal failure. 740 Jun 68

The purpose of this study is to observe the effect of electroacupuncture at "Taixi" point (KI-3) on the renal blood flow (RBF) under the condition of glycerol-induced renal ischemia and the changes of thromboxane A2 (TXA2) and prostacyclin (PGI2) during this course. The RBF, which is measured by hydrogen gas clearance method, was chosen as an index. The results are as follows: 1. After electroacupuncture at "Taixi" point, the RBF increased. 2. Under the condition of renal ischemia, the TXA2 increased, and the PGI2 decreased. 3. During the course of electroacupuncture at "Taixi" point, the TXA2 decreased and the PGI2 increased. These facts suggest that the effect of electroacupuncture at "Taixi" point is related to the PGI2 and the TXA2.
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PMID:[Effect of electroacupuncture at "taixi" point on plasma thromboxane A2 and prostacyclin in the rabbit with renal ischemia]. 792 25

The potential of using fast magnetic resonance (MR) imaging in conjunction with apnea-induced blood deoxygenation for the noninvasive monitoring of relative perfusion in the rat abdomen has been studied with two experimental models: glycerol-induced focal renal ischemia and transplanted liver tumor. Gradient-echo echo-planar imaging (GRE-EPI) (TE of 20 msec at 2T) of liver and kidney was performed before, during, and after a 60-second apnea episode and then was followed in the same rat by contrast-enhanced (a) GRE-EPI and (b) T1-weighted spin-echo imaging (TR msec/TE msec = 200/6) with polylysine-(gadolinium-DTPA [diethylenetriaminepentaacetic acid]). The results indicate that a noninvasive vascular challenge due to apnea can be used for the detection of focal tissue perfusion abnormalities in rat kidney and liver tumor.
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PMID:MR imaging of blood oxygenation-dependent changes in focal renal ischemia and transplanted liver tumor in rat. 832 7

Kidneys of newborn (but not adult) mice are normally high permissive for polyomavirus (Py) infection and readily establish persistent infections. We have proposed that ongoing cellular differentiation, which occurs in newborn mice, may be necessary for a high level of in vivo Py replication (R. Rochford, J. P. Moreno, M. L. Peake, and L. P. Villarreal, J. Virol. 66:3287-3297, 1992). This cellular differentiation requirement may also be necessary for the reactivation of a persistent Py kidney infection and could provide an alternative to the accepted view that reactivation results from immunosuppression. To examine this proposal, the ability of adult BALB/c mouse kidneys to support primary acute Py infection or to reactivate previously established persistent Py infections after kidney-specific damage was investigated. Kidney damage was induced by both chemical (glycerol, cisplatin, or methotrexate) and mechanical (through renal artery clamping to produce unilateral renal ischemia) treatments. We also examined the effects of epidermal growth factor (EGF), which enhances the rate of kidney regeneration, on Py replication. Using histopathologic techniques, in situ hybridization for Py DNA, and immunofluorescence for Py VP1 production, we established that both chemical damage and damage through renal artery clamping of adult kidneys promoted high levels of primary Py replication in these normally nonpermissive cells. This damage also promoted the efficient reactivation of Py replication from persistently infected kidneys, in the absence of immunosuppression. EGF treatment significantly increased acute Py replication and also reactivation in damaged kidneys. These results support the view that ongoing cellular division and differentiation may be needed both for high levels of acute Py replication and for reactivation of persistent infections in vivo.
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PMID:Adult mouse kidneys become permissive to acute polyomavirus infection and reactivate persistent infections in response to cellular damage and regeneration. 838 4

Stressful stimuli such as heat, oxidative stress, heavy metals, and tissue trauma induce the expression of a family of proteins commonly referred to as stress proteins or heat shock proteins. The functions of these proteins are varied but include glycolysis, antioxidant defense, and several postulated "chaperone" functions involving the folding, unfolding, and translocation of other proteins. Heme oxygenase, the enzyme that catalyzes the degradation of heme to biliverdin, is also heat inducible and is, therefore, a heat shock protein. In the kidney, ischemia has been observed by several investigators to induce expression of the more commonly studied heat shock proteins HSP 70 and HSP 72. In addition, exposure of the kidney to myoglobin after glycerol injection induced heme oxygenase. The purpose of this study was to determine whether heme oxygenase is expressed as a stress protein after renal ischemia. Renal ischemia was induced in rats after right nephrectomy by clamping the renal artery for 40 minutes. Gene expression was evaluated after 60 minutes to 96 hours of postischemic reperfusion. There was essentially no expression of heme oxygenase at any of the time points evaluated. The absence of heme oxygenase expression was in striking contrast to the prompt and dramatic expression of HSP 70. This finding is consistent with the concept that all "stress proteins" are not equivalent and that, although there is considerable overlap between heat-sensitive gene promoters and oxidant stress-sensitive gene promoters, there is specificity for the type of stimulus that is able to activate any given stress protein gene.
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PMID:Heme oxygenase is not expressed as a stress protein after renal ischemia. 840 10

The purpose of this study is to observe the effect of electroacupuncture at "Shenshu" point (U.B.-23) on the renal blood flow (RBF) under the conditions of normal, glycerol-induced renal ischemia and renal neurotomy. The RBF, which is measured by hydrogen gas clearance method, was chosen as index. The results are as follows: 1. RBF is decreased by electroacupuncturing "Shenshu" point under both conditions of normal and glycerol-induced renal ischemia. 2. After renal neurotomy, RBF is increased by electroacupuncturing "Shenshu" point. These facts suggest that the effects of electroacupuncture at "Shenshu" point relate to the renal nerve and body fluid.
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PMID:[Effect of electroacupuncture at "shenshu" point on renal blood flow in rabbits]. 870 71


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