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Oxalate induced renal calculi formation and the associated renal injury is thought to be caused by free radical mediated mechanisms. An in vivo model was used to investigate the effect of phycocyanin (from Spirulina platensis), a known antioxidant, against calcium oxalate urolithiasis. Male Wistar rats were divided into four groups. Hyperoxaluria was induced in two of these groups by intraperitoneal infusion of sodium oxalate (70 mg/kg) and a pretreatment of phycocyanin (100 mg/kg) as a single oral dosage was given, 1h prior to sodium oxalate infusion. An untreated control and drug control (phycocyanin alone) were also included in the study. We observed that phycocyanin significantly controlled the early biochemical changes in calcium oxalate stone formation. The antiurolithic nature of the drug was evaluated by the assessment of urinary risk factors and light microscopic observation of urinary crystals. Renal tubular damage as divulged by urinary marker enzymes (alkaline phosphatase, acid phosphatase and gamma-glutamyl transferase) and histopathological observations such as decreased tubulointerstitial, tubular dilatation and mononuclear inflammatory cells, indicated that renal damage was minimised in drug-pretreated group. Oxalate levels (P < 0.001) and lipid peroxidation (P < 0.001) in kidney tissue were significantly controlled by drug pretreatment, suggesting the ability of phycocyanin to quench the free radicals, thereby preventing the lipid peroxidation mediated tissue damage and oxalate entry. This accounts for the prevention of CaOx stones. Thus, the present analysis revealed the antioxidant and antiurolithic potential of phycocyanin thereby projecting it as a promising therapeutic agent against renal cell injury associated kidney stone formation.

It has been reported that the urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG), a lysosomal enzyme, transiently increases in human after treatment with human parathyroid hormone (hPTH)(1-34). We report here that hPTH(1-34) caused transient changes in the size and density of rat renal lysosomes following urinary excretion of NAG and other lysosomal enzymes tested. Percoll density gradient centrifugation revealed that hPTH(1-34) slightly but significantly increased the fraction of high density lysosomes (around 1.12 g/ml) 5-10 min after the treatment with hPTH(1-34), with a concomitant decrease in the fraction of intermediate density lysosomes (1.07-1.08 g/ml). On electron micrographs, some lysosomes in proximal tubules but not in distal tubules showed a change in morphology from circular to oval, and became enlarged and electron-dense 5-10 min after the treatment with hPTH(1-34). These responses to hPTH(1-34) were also reversible and transient. NAG excreted in urine after treatment with hPTH(1-34) had the molecular mass of a mature form in lysosomes and/or endosomes and was not a prepro-and/or pro-form of the enzyme. Thus, the changes in the density and size of renal lysosomes appear to be associated with the exocytosis of lysosomal enzymes by hPTH(1-34).

The loop diuretic, furosemide, which has been known to elicit renin release in vivo as well as in vitro, has also been shown to induce lysosomal enzyme release. After administration of furosemide (10 mg/kg and 300 mg/kg), a significantly increased acid phosphatase activity (1.33 x 10(-4) and 1.73 x 10(-4) vs. 0.23 x 10(-4) U, p < 0.001) was detected in the urine of the drug-treated mice, accompanied by a reduction of the residual enzyme activity in the kidney (5.0% for 10 mg/kg and 18.4%--p < 0.05--for 300 mg/kg dosage). Two marker enzymes, acid phosphatase and beta-D-glucuronidase, were assayed to demonstrate that furosemide also exerts its effect in in vitro systems like renal cortex suspension (corr. coeff.: 0.899 for acid phosphatase and 0.908 for beta-D-glucuronidase, p < 0.001) and isolated lysosomes (corr. coeff.: 0.981 for acid phosphatase and 0.989 for beta-D-glucuronidase, p < 0.001 for both). This action of the drug seems to be different from the well-known furosemide-sensitive inhibition of ion transport systems and may become of clinical relevance for patients receiving high doses of furosemide.

Manipulations of metabolic acid-base status were used in an attempt to modify the renal handling and toxicity of the anticancer drug cisplatinum. Rats were orally pretreated with either tap water (TW), ammonium chloride (AC), or sodium bicarbonate (SB) for 3 days prior to intraperitoneal administration of a high cisplatinum dose (7.5 mg/kg b.w.). Urine was collected daily for 4 days between drug dosing and killing of the animals. AC-pretreated rats did not exhibit the characteristic cisplatinum-induced diuresis and were unable to maintain an acid urinary pH following drug administration. AC rats had a significantly lower, and SB rats a significantly higher, urinary excretion of platinum than did TW rats. Platinum excretion was found to be correlated with urinary pH (r = 0.88) and not urinary volume (r = 0.30). The renal concentration of platinum was greater in AC animals than in SB or TW animals, but no significant difference was observed in liver or plasma concentrations between the groups. Both pretreated groups had equal percent of free vs bound platinum. Proteinuria was more severe in AC-pretreated rats, but histologic evidence of renal tubular damage was present in all the three groups. It is concluded that metabolic acidosis can seriously impair the renal handling of high dose cisplatinum but that metabolic alkalosis offers no evident advantages over nonpretreatment.

Enzymuria observed in PCM, especially in severe cases, does not seem to be a simple reflection of the increased serum values and suggests renal involvements. A number of factors among which are :- lowered clearance threshold for certain enzymes as well as rapid wear and tear or renal cells seem to participate in the causation of such enzymuria. Urine enzyme analysis may reflect the extent and state of renal pathology among different forms of PCM.

The effect of administration of suramin on the urinary levels of some lysosomal enzymes in rats was investigated. The urinary levels of acid phosphatase and lysozyme were significantly elevated 24 h after drug administration. The high levels were sustained for 9 days after drug administration was terminated. These actions were indicative of labilization of kidney lysosomal membrane by the drug molecules, the membrane being repaired and integrity restored some days following termination of drug administration.

The activity of several enzymes with different intracellular sites was determined in urine at various times following nonfatal acute tubular necrosis induced by mercuric chloride administration. The excretion rate of all tested enzymes rose on the 1st and 2nd day; in the next observations (days 7-15) enzymatic values approached the basal values. The lactate dehydrogenase isoenzyme pattern of the renal cortical zone showed an early shift towards cathodic fractions and later (7 days) an increase of middle ones; the normal anodic zymogram recovered after a suitable time interval (30 days). The isoenzymatic changes are related both to the renal hypoxia and to the appearance of less differentiated cells. The behaviour of functional parameters (urine flow, osmolality, urea clearance, creatinine clearance) were well in agreement with the observed enzyme and renal isoenzyme changes.

Two groups of rats were given aspirin and phenacetin in their food at daily doses similar to those taken by humans suffering from analgesic abuse. Both drugs damaged the kidney proximal tubules although phenacetin affected the kidney more severely than aspirin. At the start of the experiment aspirin increased the urinary excretion of lactate dehydrogenase (LDH) while phenacetin raised the excretion of all four enzymes studies (acid phosphatase, alkaline phosphatase, glutamate dehydrogenase (GDH), LDH indicating generalised cellular injury. Subsequent samples of urine collected from rats up to seven weeks showed normal urinary enzyme levels. The value of urinary enzyme measurements in detecting renal damage by drugs is discussed.

1. Chronic administration of chloroquine to rats results in increased urinary excretion of lysosomal acid phosphatase, muramidase and cathepsin D. 2. Various concentrations of chloroquine caused lysosomal membrane swelling as shown by decrease of light absorbance in lysosomal suspensions. 3. Incubating lysosomal suspensions in the presence of chloroquine resulted in a marked lysosomal acid phosphatase release. 4. Addition of acetylsalicylic acid, a lysosomal membrane stabilizer, into a lysosomal suspension containing chloroquine, reduced the degree of lysosomal membrane swelling and acid phosphatase release. 5. The results suggest a labilizing effect of chloroquine on rat kidney lysosomes.

The origin of urinary trehalase in mercuric chloride-induced nephrotoxic rabbits was demonstrated with biochemical and immunochemical techniques. Urinary trehalase was dramatically increased with HgCl2-induced nephrotoxicity. The nephrotoxic kidney showed an extreme decrease in specific fluorescence with fluorescein isothiocyanate (FITC)-conjugated antibody technique. Moreover, trehalase activity in the membrane fraction was remarkably decreased in the nephrotic kidney compared with the control. Judging from the results of immunodiffusion, urinary trehalase and renal trehalase exhibit the same antigenicity. From the data of a time course analysis of nephrotoxicity, the excretion of urinary trehalase was earlier than that of urinary sugar. Previous results show that renal trehalase is localized in the renal tubular brush borders. From these results, it is suggested that urinary trehalase is originated in the renal brush borders. In consideration of the results described in previous papers and in this paper, it is proposed that urinary trehalase is a good indicator of renal brush border damage.

The administration of cephaloridine to rats caused a decrease in the excretion of acid phosphatase into the urine. The antibiotic itself had no effect on urinary acid phosphatase and inhibitors or proteolytic enzymes were not present in the urine from treated rats. Cephaloridine may therefore be stabilizing the lysosomal membrane in vivo and experiments with isolated lysosomes confirm this hypothesis. The lysosomal integrity was followed by measuring the acid phosphatase activity and the light scattering properties of the particles. A good correlation was obtained between these parameters in the case of thermal disruption and progesterone induced lysis of the lysosomes and low concentrations of cephaloridine (0.1-1.0 mmol/1) protected the lysosomes against this form of damage.

The relative sensitivity of urinary enzyme measurements for detecting renal damage was determined for two nephrotoxins. Injection of a single dose of sodium phosphate (10 mmoles/kg) caused damage to the proximal tubules and led to a 15 fold increase in lactate dehydrogenase (LDH) activity excreted into the urine. In contrast to this change the serum LDH remained normal. Similar results were obtained following the injection of cephaloridine (2 g/kg) with an 18 fold increase in urinary LDH and a marginal increase in urinary glutamate dehydrogenase (GDH). By contrast the serum LDH was unchanged. Urinary enzymes are therefore more sensitive for detecting renal injury than enzymes. The four enzymes investigated are located in specific regions of the cell so that the involvement of the organelles and regions of the cell can be followed. Damage to the organelles does not appear to occur as the excretion of the lysosomal enzymes remained normal and only in the case of cephaloridine were marginal changes in the mitochondrial GDH excretion seen. The average alkaline phosphatase was also normal suggesting no gross damage to the plasma membrane although a few individual rats excreted abnormal activities of alkaline phosphatase. These rats however, also excreted high activities of LDH. This suggests that damage to the membrane causes leakage of LDH and in severe cases release of the plasma membrane enzyme alkaline phosphatase. The administration of cephaloridine at various doses showed that urinary enzyme measurements were as sensitive as histology for demonstrating renal damage and that of these enzymes, LDH was by far the most useful.

The release of kallikrein into the perfusate and urine of the isolated perfused rat kidney was studied. Comparison between enzymic and immunological assays for kallikrein demonstrated the presence of an enzymically inactive form of kallikrein. Of kallikrein found in normal rat urine 77 +/- 4% is active and 23% is in an inactive form. In the isolated perfused rat kidney a similar proportion of active kallikrein (84%) was excreted into the urine but very little enzymically active kallikrein (2%) could be detected in the perfusate. However, significant amounts of enzymically inactive but immunologically reactive kallikrein could be found in the kidney perfusate. The rate of release of kallikrein into the perfusate was approximately one-fifth of the rate of release into the urine. Renin showed a similar pattern of release into the perfusate and urine but the lysosomal enzyme marker acid phosphatase was not detectable. These results show that kallikrein is secreted from the kidney into the circulation as well as being excreted in the urine. However, in urine the enzyme is predominantly in an enzymically active form whereas it is secreted into the circulation in an inactive form.