Ethanol—Its Nephrotoxic Effect in the Rat

The nephrotoxic effect of ethanol feeding on renal structure and function was evaluated in rats and compared to that in dextrose-fed isocaloric control animals. Alcohol-fed animals had larger kidneys than their controls. Despite this increase in renal mass, the alcohol-fed animals had a 50% reduction in creatinine clearance and a 67% reduction in osmolar clearance compared to their controls. When specific renal constituents were compared, the alcohol-fed animals were found to have twice the renal protein and a 50% increase in renal lipid. Despite these marked structural and functional differences, the light microscopic appearance of the kidneys of the two groups did not appear significantly different. In contrast, the electron microscopic differences were substantial. The renal epithelial cells, particularly of the distal tubules and Henle's loops, were found to show varying degrees of cellular injury and were observed to be sloughing into the lumens. These electron microscopic observations are similar to those obtained in tubular necrosis due to a variety of nephrotoxic agents. We propose, therefore, that chronic alcohol feeding of rats produces significant renal dysfunction and abnormalities of structure such that ethanol should be considered a true nephrotoxin.     

Compensatory renal hypertrophy in hypophysectomized rats

1. After hypophysectomy, both body and kidney weights fall, but at different rates. The rate at which the kidney decreases in weight is faster than that of the whole body.2. Seven days after unilateral nephrectomy, the dry weight of the remaining kidney of hypophysectomized rats, with the exception of rats which had been hypophysectomized for 2 days only, was always heavier than the kidney of control hypophysectomized rats of similar body weight.3. The difference between the dry weight of kidneys of unilaterally nephrectomized hypophysectomized and control hypophysectomized rats increased from 15% in early hypophysectomized (9 days) to about 35% in late hypophysectomized animals (23 days).4. The implantation of renal cortical cells from 2 day hypophysectomized rats into unilaterally nephrectomized control litter-mates inhibited compensatory renal hypertrophy in the latter. When a similar operation was made using kidney cells from animals which had been hypophysectomized for 23 days, there was no significant inhibition of compensatory renal hypertrophy.5. The renal contents of adenosine-3',5'-monophosphate (cyclic AMP) and of guanosine-3',5'-monophosphate (cyclic GMP) in rats hypophysectomized for 2 days were of the same order as those in normal rats, but were markedly lower in rats hypophysectomized for 23 days.6. In contrast to what had been observed in normal rats, in hypophysectomized (2 or 23 days) rats, unilateral nephrectomy did not affect significantly the levels of cyclic nucleotides in the remaining kidney.7. Cross-circulating anephric normal rats with 2 day hypophysectomized animals resulted in an increase of cyclic GMP content in their kidneys. The cross-circulation between anephric normal rats and 23 days hypophysectomized rats had no effect on the level of renal cyclic GMP of the latter.8. When rats hypophysectomized for either 2 or 23 days and which had been nephrectomized were cross-circulated with normal rats, there were no changes in the content of cyclic GMP in the kidneys of the latter.     

Regulation of compensatory kidney hypertrophy by its own products

1. The ligation of blood vessels of one kidney of adult rats resulted in the compensatory hypertrophy of the other kidney. In most animals the rate of hypertrophy was indistinguishable from that observed after unilateral nephrectomy, but in a few cases the onset was retarded when the renal artery alone had been ligated and the collateral circulation increased.

2. When the blood vessels of one kidney of adult rats were ligated and the cortex was excised, the rate of compensatory renal hypertrophy was similar to that observed after unilateral nephrectomy.

3. In animals operated for simultaneous partial hepatectomy and unilateral nephrectomy, there was no sign of compensatory renal hypertrophy while the liver was undergoing regeneration. Renal hypertrophy started after 7 days, when about 98% of the amount of liver removed had been regenerated.

4. Neither aseptic autolysis of one kidney following suppression of its blood supply, nor unilateral nephrectomy affected the rate of liver regeneration after simultaneous partial hepatectomy.

5. Total splenectomy did not affect the rate of compensatory renal hypertrophy following unilateral nephrectomy.

6. The heterotopic graft of renal cortical, but not of medullary, cells inhibited compensatory renal hypertrophy in adult rats. The removal of the graft after 14 days was followed by the resumption of compensatory hypertrophy.

7. The inhibiting action of fractions of renal cortical extracts fractionated on Sephadex G100 resin and DEAE-52 cellulose were assayed on the `growth' of renal explants reared in vitro. The final material, though only partially purified, proved to have an inhibiting activity between 250 and 500 times greater than that of the initial extract.

8. When injected into unilaterally nephrectomized rats, the partially purified extract from the renal cortex had an inhibiting effect on compensatory renal hypertrophy.

9. Immunofluorescence technique showed that the partially purified cortical extract affected the proximal convoluted tubes specifically, irrespective of animal species.

     

Regeneration of the kidney following compensatory hypertrophy

Summary Left kidney was removed in sexually mature rats; in a month 1/3 of the remaining kidney was resected. Comparative study of changes occurring in the regenerating kidney and those taking place in the kidneys undergoing compensatory hypertrophy (conducted for the period of 1 and 3 months) demonstrated that they are somewhat different. The regenerating kidney approaches the kidneys undergoing compensatory hypertrophy by its size and weight, but is much larger than the kidneys of control animals. Malpighian bodies and tubules are larger in size in regenerating kidney than in the kidneys of control animals and in the organs which underwent compensatory hypertrophy. This enlargement is mainly, caused by the cellular hyperplasia. As to compensatory hypertrophy, cellular hypertrophy is the main process occurring.Presented by Active Member AMN SSR V. N. Chenigovskii     

Kidney morphology in hemolytic-uremic syndrome

Morphology of the kidneys in hemolytic-uremic syndrome is considered basing on autopsy findings obtained for 3 infants with 5-17-day history of acute renal failure. A newborn infant of 17 days developed the disease after feto-fetal hemotransfusion when macerated fetus-donor hemolysis products entered the circulation of the fetus-recipient through monochorionic placenta. The second case in an infant of 6 months was due to ADTP Vaccine. The last infant aged 16 months manifested the syndrome in the presence of Proteus-induced ulcerative colitis. Varying in etiology, renal morphology exhibited similar features: fibrin deposits in the lumens of glomerular capillary loops, afferent glomerular arterioles and intrarenal arteries; fibrinoid necrosis of the wall in the arterioles. The renal affection ranged from acute thrombotic glomerulonephritis to cortical necrosis, these variations being dependent on the degree of thrombogenesis, caliber of impaired intrarenal vessels and time from the onset of acute renal failure.     

Early and persistent up-regulated expression of renal cortical osteopontin in experimental hydronephrosis.

The mechanical disturbance after unilateral ureteral obstruction (UUO) is a nonimmune stimulus that is capable of eliciting a florid macrophage infiltration of the kidney and subsequent post-inflammatory renal scarring. Osteopontin has potential chemoattractant activity and, for this reason, we delineated the kinetics of its expression in the renal cortex of rats with UUO. Whole body X-irradiation and reversal of UUO were utilized as interventional maneuvers to give additional pathobiological insight into this protein's role in the response of the kidneys to ureteral obstruction. Increased osteopontin mRNA levels in obstructed kidneys versus contralateral unobstructed specimens were evident as early as 4 hours after UUO and steadily increased at 12, 24, 48, and 96 hours after UUO. Both X-irradiation and reversal of UUO failed to significantly modulate renal cortical osteopontin mRNA expression at all of the above time points. Paralleling the increments in renal cortical osteopontin mRNA levels were significant elevations in the cortical renal interstitial macrophage number, which was significantly diminished by previous X-irradiation but not reversal of UUO. Focal labeling of osteopontin was noted in both tubular and Bowman's capsular epithelium in obstructed kidneys as early as 4 hours after UUO, whereas, in the contralateral unobstructed specimens, there was only faint staining in Bowman's capsule. By 96 hours after UUO, obstructed kidneys exhibited intense, diffuse staining for osteopontin in both tubules and Bowman's capsule. Osteopontin's immunolocalization was not modulated by X-irradiation or reversal of UUO. These data support the contention that osteopontin is involved in the accumulation of macrophages within the peritubular and periglomerular interstitium in the obstructed renal cortex.     

Experimental renal papillary necrosis in the rat: The selective vulnerability of medullary structures to injury

Summary Acute renal papillary necrosis was produced in rats by the administration of ethyleneimine. Low doses resulted in necrosis of interstitial cells, thin limbs of the loops of Henle and vasa recta, while collecting ducts were spared (subtotal renal papillary necrosis). High doses resulted in necrosis of all elements of the papilla (total renal papillary necrosis). Although the ranges of the doses that produced these two patterns of necrosis overlapped, it is clear that there is a dose dependent selective vulnerability of renal medullary structures to injury by the toxic agent studied.     

Hormonal influences on compensatory renal hypertrophy

Summary In animals kept in the cold, compensatory hypertrophy of the kidneys after unilaterial nephrectomy was considerably greater than in animals kept in warmth. It is quite probable that the effect of cold depends on the intensified secretion of the thyrotropic hormone by the hypophysis, because the introduction of methylthiouracil, which increases the secretion of this hormone, was accompanied by a considerable increase of compensatory renal hypertrophy.Submitted by Active Member of the Academy of Medical Sciences USSR L. A. Orbeli     

The Excretion of Renal Cells Following Necrosis of the Distal Segment of the Nephron by Hexadi-Methrine Bromide

The rate of excretion of renal cells was determined in rats with necrosis of the distal convoluted tubules and broad ascending limbs of the loops of Henle caused by injection of hexadimethrine bromide. The magnitude and the duration of abnormal cell excretion were correlated both with the dose of hexadimethrine and with the degree of damage that was evident on histological examination of the kidney.In general cell excretion studies provided a satisfactory indication of the degree of renal damage but the smallest lesions did not cause a significant increase in cell excretion and occasionally a rat with a very large lesion failed to show an increase in cell excretion rate.The changes in excretion rates observed in the present experiments were less than those found previously in animals with necrosis of proximal convoluted tubules caused by mercuric chloride. This is probably due firstly to the smaller number of cells in the distal nephron and secondly to the toxin causing disintegration of many of the cells.These findings have implications for the investigation of analgesic nephrotoxicity by measurement of urinary cell excretion rates. In order to appreciate the significance of increases in renal cell excretion following administration of various substances their site of action and the type of cell damage that they cause must first be established.     

Effect of inhibitors of prostaglandin synthesis on the furosemide action in the loop Henle of rat kidney

Inhibitors of prostaglandin synthesis such as indomethacin and meclofenamate may attenuate the diuretic response to furosemide. The purpose of the present study was to clarify whether an inhibition of furosemide's action in the loop of Henle is involved in this interaction. In a first set of experiments, the effect of indomethacin and meclofenamate on the diuretic response to furosemide was re-evaluated in anaesthetized rats. Single loops of Henle of rat kidneys were perfused in vivo in a second group of rats. Furosemide was added to the perfusion fluid and the effect of indomethacin (5 mg/kg i.v.) and meclofenamate (5 mg/kg i.v.) on furosemide's action in the loops was tested. In the absence of furosemide, indomethacin and meclofenamate did not significantly affect urine flow and sodium chloride excretion, or the loop's sodium and chloride reabsorption. Both prostaglandin inhibitors, however, significantly attenuated the diuretic effect of furosemide (1 mg/kg i.v.) and the inhibitory action of the diuretic, at a concentration of 10^–4 M, on the loop's sodium and chloride transport. The results identify the loop of Henle as a tubular site of interaction between furosemide and prostaglandin inhibitors. The interaction may be related to a furosemide-induced stimulation of renal prostaglandins.Parts of this study were presented at the spring meeting of the German Pharmacological Society, Mainz 1987 (Naunyn-Schmiedeberg's Archives of Pharmacology 335, R48, 1987)     

Studies on cell proliferation and tracer localization in the kidneys of guinea pigs with experimental autoimmune anti-tubular basement membrane nephritis

The mitotic activity in kidneys of guinea pigs with experimental autoimmune anti-tubular basement membrane (TBM) nephritis was investigated using autoradiographic techniques to determine the uptake of [3H]thymidine by actively dividing cells. It was observed in these animals that cells of proximal tubules, distal tubules, cortical and medullary interstitium, medullary collecting ducts, and loops of Henle took up significantly greater amounts of [3H]thymidine when compared with normal animals. In addition, the behaviour of horseradish peroxidase (HRP) and goat anti-HRP IgG in extraglomerular sites in the kidneys of these animals was studied. Contrary to what was expected, these tracers appeared to be less concentrated in the tubules and interstitium of animals with anti-TBM disease, with tracer movement restricted in areas of disrupted TBM. The significance of these observations is discussed.     

Tubular organization and vascular-tubular relations in the dog kidney.

Tubular organization and vascular-tubular relations were studied by double injection in canine kidneys. Blood vessels were injected via the artery after perfusion fixation. Tubules were injected by micropipettes inserted into the urinary spaces of selected glomeruli in cleared slices. One hundred proximal convoluted tubules, 16 Henle loops, and 5 distal convoluted tubules were defined. Only subcapsular proximal convolutions were perfused by efferent vessels arising from the same glomerulus (43 of 55). In midcortex, proximal convolutions were generally perfused over less than half their length by the parent efferent (21 of 31). Here tubules entirely perfused by the parent efferent were rare (2 of 31). No inner cortical proximal convolutions were perfused by the efferent from the same glomerulus (0 of 14). Henle's loops were found to be perfused by the efferents of many glomeruli regardless of the cortical position of the parent glomerulus. Distal convolutions shared the perfusion of proximal convolutions of the same glomerulus. Thus, each nephron is apparently functionally dependent on efferent blood from glomeruli of many other nephrons. New synoptic diagrams of canine renal organization are presented.     

Long-term evolution of the acute tubular necrosis (ATN) induced by glycerol: role of myofibroblasts and macrophages

Late structural changes such as interstitial fibrosis in the renal cortex and tubular atrophy have been detected after severe acute tubular necrosis (ATN). The aim of this study was to investigate the expression of fibronectin, alpha-smooth muscle actin and macrophages during the evolution of the ATN induced by glycerol and their relationship with the late structural changes observed in the kidneys of these animals. Forty-nine male Wistar rats were injected with a 50% glycerol solution, 8 mL/kg (4 mL/kg applied i.m. to each hind leg) and 14 with 0.15 m NaCl solution. Before glycerol injection on day 1, water was removed for 17 h. Blood and urine samples were collected 1 day after the injection to quantify sodium and creatinine. The animals were killed 5, 30 and 60 days after the injections and the kidneys removed for histological and immunohistochemical studies. The results of the histological and immunohistochemical studies were scored according to the extent of lesion or staining in the cortical tubulointerstitium, respectively. The percentage of tubulointerstitial lesions was determined by morphometry. Glycerol-injected rats presented a transitory increase in plasma creatinine levels and in fractional sodium excretion. The immunohistochemical studies showed increased fibronectin, alpha-smooth muscle actin (alpha-SM-actin), TGF-beta and ED-1 (macrophages) staining in the renal cortex from rats killed 5, 30 and 60 days after glycerol injection (P < 0.05) compared to control. The animals killed on day 30 and 60 also presented chronic lesions (fibrosis, tubular dilatation and atrophy) in the renal cortex, despite the recovery of renal function. Macrophages, TGF-beta and myofibroblasts may have contributed to the development of renal fibrosis in these rats.     

Effects of diuretic states on collecting duct fluid flow resistance in the hamster kidney.

Hydrostatic pressures were measured in cortical tubules, long loops of Henle, terminal collecting ducts, and in vasa recta in hamsters. In hydropenia, the loops of Henle and terminal collecting ducts provided the major fluid flow resistances, as judged by the location of hydrostatic pressure drops. In mannitol or saline diuresis, hydrostatic pressures in all tubular segments increased, but pressure drops in loops of Henle disappeared, indicating dilatation of loops. The major pressure drop was in terminal collecting ducts, especially in ducts of Bellini, even though these tubular segments also dilated. At highest urine flows, cortical tubule pressures were higher with the ureter and renal pelvis intact than when they were excised, suggesting laminar flow in the ureter adds a flow resistance at high flows. The pressure drop across the medullary capillary bed was 1-2 mmHg. The summation of medullary capillary hydrostatic and colloid osmotic pressures favored fluid uptake from the interstitium, a relationship enhanced by vasa recta geometry which ensures that descending vasa recta offer 4 times the flow resistance of ascending vessels.     

Nephron segment localization of polyoma virus large T antigen in renal allografts

This study uses CD10 and epithelial membrane antigen (EMA) as respective proximal and distal tubular segment markers to localize polyoma virus replicative activity, as determined by large T antigen (TAg) expression, in allograft polyoma virus nephropathy (PVN). Sixteen biopsies and 2 nephrectomy specimens with PVN had serial 2-mum paraffin sections stained using monoclonal antibodies to polyoma virus TAg by immunoperoxidase with diaminobenzidine as chromogen. A second immunolabeling step used CD10 as a proximal nephron marker or EMA as a distal tubular marker, and alkaline phosphatase with fast red as chromogen. BK viral DNA was detected in blood in 16 of 18 tested. Fourteen of 16 had cortex and medulla, and 2 had cortex only in the biopsy sample. Fourteen (100%) of 14 had double-positive EMA and TAg expression (EMA+TAg+) in medullary collecting ducts. T antigen was evident in loops of Henle in nephrectomies. Thirteen (81.3%) of 16 had EMA+TAg+, and 10 (62.5%) of 16 had CD10+TAg+ cortical tubular segments. CD10+TAg+ cells were observed in the parietal epithelium of Bowman's capsule in 3 biopsies (18.75%). T antigen was observed in 5.1% of CD10+ tubular profiles compared with 21% of EMA+ profiles in renal cortex (P < .0001). Polyoma virus TAg was observed in medullary collecting ducts, in distal and proximal cortical tubules, and in Bowman's capsule, in decreasing order of frequency. Loops of Henle also had TAg. This distribution suggests potential for an ascending route of infection of allograft tubules in PVN.     

大鼠缺血性肾损伤的细胞聚合糖性死亡与外源性凋亡

目的探讨大鼠肾缺血再灌注所致急性肾损伤时细胞聚合糖性死亡与外源性凋亡。方法应用免疫印迹技术、免疫组织化学染色技术以及光学和电子显微镜技术对缺血60min再灌注24h的大鼠肾组织进行观察和分析。结果免疫印迹分析结果表明,与sham组比较肾缺血再灌注后(AKI组)肾组织PARP-1、caspase-3和TNFRα表达增强。PARP-1、caspase-3免疫组化染色阳性细胞出现在缺血再灌注损伤肾组织,主要分布于肾小管,皮质和髓质外带的肾小管出现了大面积细胞坏死,表现为细胞肿胀,空泡形成,崩解脱落。在髓质外带肾小管坏死细胞之间存在着较多的凋亡细胞,细胞皱缩,核固缩。电镜下坏死细胞肿胀,细胞器也肿胀,崩解消失。凋亡细胞皱缩,界限清楚,核染色质固缩边聚。结论大鼠肾缺血60 min再灌注24 h部分肾小管上皮细胞发生聚合糖性死亡和外源性凋亡。     

Early pathophysiological features in canine renal papillary necrosis induced by nefiracetam

To ascertain the early pathophysiological features in canine renal papillary necrosis (RPN) caused by the neurotransmission enhancer nefiracetam, male beagle dogs were orally administered nefiracetam at 300 mg/kg/day for 4 to 7 weeks in comparison with ibuprofen, a non-steroidal anti-inflammatory drug (NSAID), at 50 mg/kg/day for 5 weeks. During the dosing period, the animals were periodically subjected to laboratory tests, light-microscopic, immunohistochemical, and electron-microscopic examinations and/or cyclooxygenase (COX)-2 mRNA analysis. In laboratory tests, a decrease in urinary osmotic pressure and increases in urine volume and urinary lactate dehydrogenase (LDH) level were early biomarkers for detecting RPN. Light-microscopically, nefiracetam revealed epithelial swelling and degeneration in the papillary ducts in week 7, while ibuprofen displayed degeneration and necrosis in the papillary interstitium in week 5. In immunohistochemical staining with COX-2 antibody, nefiracetam elicited a positive reaction within interstitial cells around the affected epithelial cells in the papillary ducts (upper papilla) in week 7, and ibuprofen positively reacted within interstitial cells adjacent to the degenerative and/or necrotic lesions in week 5. Ultrastructurally, nefiracetam exhibited reductions of intracellular interdigitation and infoldings of epithelial cells in the papillary ducts, whereas ibuprofen showed no changes in the identical portions. Thus, the early morphological change in the papilla brought about by nefiracetam was quite different from that elicited by ibuprofen. By the renal papillary COX-2 mRNA expression analysis, nefiracetam exceedingly decreased its expression in week 4, but markedly increased it in week 7, suggesting an induction of COX-2 mRNA by renal papillary lesions. These results demonstrate that the epithelial cell in the papillary ducts is the primary target site for the onset of RPN evoked by nefiracetam.     

Calcification in the renal medulla: A clasification based on a prospective study of 2261 necropsies

Kidneys from 1864 necropsies performed in Brisbane, Australia, and from 397 necropsies performed in Christchurch, New Zealand, were examined macroscopically and microscopically. Three zonal and three focal patterns of renal medullary calcification were defined: (1) Outer medullary cortical calcification seen in hypercalcemic conditions. (2) A band of calcification at the boundary of the inner and outer medulla associated with degenerative changes and correlated with aging and arteriolar disease. (3) Calcification concentrated around the loops of Henle in the papilla, sometimes a striking finding in children and common at all ages. Heavy calcification in this region was injurious to the loops. (4) Fine focal calcification in random distribution throughout the medulla. This lesion was seen in virtually all adult necropsies to some degree. (5) Coarse focal deposits in the papillary region, more common in males and in a hotter climate. (6) Randall's plaques also were common in males and in a hotter climate.     

Morphologic and functional evidence for oxygen deficiency in the isolated perfused rat kidney

Morphologic and functional studies were undertaken in the isolated rat kidney, perfused with an albumin-Krebs-Henseleit solution, to which 5% human erythrocytes and/or various amino acids had been added. Perfused only with the albumin-Krebs-Henseleit solution, the kidneys displayed a characteristic pattern of cell necrosis after 2 hours of perfusion, which was confined to the interbundle region of the outer medulla and was not evident in either the cortex or the inner medulla. In the outer stripe only those proximal straight tubules (P3 segments) farthest from the vascular bundles were damaged. In the inner stripe only those thick ascending loops of Henle at the periphery of the vascular bundles escaped damage; all thick ascending loops of Henle lying farthest from the bundles were severely damaged. The number of damaged tubules increased toward the border to the inner medulla. Necroses in both segments, P3 and thick ascending loops of Henle, could be prevented by perfusion with the erythrocyte-albumin-Krebs-Henseleit solution but not by the addition of glutathione, in the absence of erythrocytes. Perfusion with the erythrocyte medium also significantly improved glomerular filtration rate and sodium and glucose reabsorption. It is concluded that, in the isolated, erythrocyte-free perfused kidney, the oxygen content of the "arterial" vasa recta in the vascular bundles is only sufficient to supply the tubules in the immediate surroundings. Countercurrent exchange in the vascular bundles between arterial and "venous" vasa recta progressively lowers the arterial oxygen content as the inner stripe of the outer medulla is approached and with it the number of tubules receiving an adequate oxygen supply.