Cellular Toxicity of X-ray Contrast Media for Two Renal Epithelial Cell Lines (MDCK and LLC-PK1)

The two renal cell lines, MDCK (distal tubule) and LLC-PK1 (proximal tubule), have been used for toxicity testing of three different X-ray contrast media: the ionic monomer Isopaque, the ionic dimer Hexabrix and the non-ionic monomer Omnipaque. The cells were grown to confluency in monolayer cultures in a chemically-defined serum-free medium before the contrast media were added, to give final concentrations corresponding to 0–100mg iodine/ml. Toxicity was assessed by cell viability and by biochemical assays of marker enzymes. The results demonstrate a concentration-dependent toxic effect from the contrast media on cellular appearance, and on the activity of brush border and lysosomal enzymes. The non-ionic X-ray contrast media appeared to be less toxic than the ionic contrast media investigated.

Urinary Protein Excretion following Intravenously Administered Ionic and Non-Ionic Contrast Media in Man

Urinary protein excretion following intravenous administration of the radiographic contrast media (CM) diatrizoate (ionic) and iopromide (non-ionic) was examined in 20 patients with normal renal function. Neither of the two CM had any effect on the 24-h urinary excretion of albumin (a marker of glomerular proteinuria). The 24-h urinary excretion of the retinol-binding protein (a marker of low molecular weight or tubular proteinuria) and the folate binding protein, a protein localized in the brush-border membranes of the proximal tubular cells, showed a statistically significant transient increase the day after diatrizoate injection, whereas no increase was observed after iopromide. Thus, only a minimal and temporary disturbance of the renal proximal tubular function was observed after diatrizoate injection in patients with normal renal function.

Gentamicin Nephropathy and Contrast Media

Urine profiles were followed for 3 or 9 days after intravenous injection of diatrizoate, iohexol or saline in 30 rats, where a tubulointerstitial nephropathy was induced by gentamicin given over a 14-day period. Another 10 rats who had an injection of saline served as controls. Iohexol increased the excretion of lactate dehydrogenase significantly more than both saline and diatrizoate for the first 3 days, whereas diatrizoate had no effect. Both media caused significantly increased excretion of L-gamma-glutamyltransferase compared with saline, but iohexol significantly more than diatrizoate. Compared with saline S-creatinine was significantly increased following iohexol at 24 h, 3 and 9 days, and following diatrizoate only at 9 days. Among rats having gentamicin light microscopy revealed more severe changes in kidneys exposed to iohexol than to either diatrizoate or saline 3 days after their injection. Six days later no obvious differences were found between the 3 groups. In conclusion, iohexol induced more renal dysfunction than diatrizoate in this animal model of gentamicin induced nephropathy.

Adriamycin Nephrosis and Contrast Media

Urine profiles (albumin, glucose, NAG, LDH, GGT and sodium) were followed for 9 days after intravenous injection of either diatrizoate, iohexol, or saline in 27 Wistar rats with nephrosis induced by Adriamycin 42 days before. Another 9 rats exposed to neither Adriamycin nor contrast media served as controls. None of the contrast media caused further increased albuminuria of significance, whereas both induced significantly increased excretion of all 5 tubular components. The excretion of NAG and sodium was significantly higher following diatrizoate than following iohexol. From 24 h post injection there was no significantly greater excretion of any of the components after either diatrizoate or iohexol than after saline among the rats given Adriamycin. At the end of day 9 after contrast medium injection neither serum sodium, potassium, glucose, urea, creatinine, nor albumin revealed any contrast media related changes. Kidney histology showed quantitatively larger lesions in kidneys exposed to Adriamycin and contrast media than in kidneys exposed to Adriamycin and saline. There were no differences between the two contrast media groups. It is thus concluded, that both high osmolar ionic and low osmolar non-ionic contrast media cause temporary tubular dysfunction but no further glomerular dysfunction in rats with nephrosis induced by Adriamycin. The histologic findings indicate that both media may worsen non-reversible renal lesions.

Nephropathy Induced by Intramuscularly Administered Glycerol and Contrast Media in Rats

Urine profiles (albumin, glucose, NAG, LDH, GGT, sodium, and phosphate) were followed for 14 days after intravenous injection of either diatrizoate, iohexol, ioxilan, or saline in 24 Wistar rats with a glomerular and tubular dysfunction induced by intramuscularly (i.m.) administered glycerol. Another 6 rats exposed to neither glycerol nor contrast media served as controls. The effect of ioxilan and saline on the albumin excretion was similar, whereas diatrizoate and iohexol increased it significantly. The contrast media had no further inhibitory effect on the reabsorption of glucose. Iohexol caused significantly increased excretion of all three enzymes, ioxilan of NAG and LDH, whereas diatrizoate only increased the excretion of LDH. The sodium excretion was further increased by ioxilan and diatrizoate, whereas none of the contrast media affected the phosphaturia. Both ioxilan and iohexol caused a round cell response around the tubules shown by light microscopy whereas diatrizoate caused no further changes. It is concluded that diatrizoate and iohexol increase glomerular dysfunction induced by glycerol i.m.; all three contrast media cause some further increase in the tubular dysfunction. Neither diatrizoate, iohexol nor ioxilan prolong nephropathy induced by glycerol i.m. determined by the chemical analyses. The histologic finding indicates a direct toxic effect of non-ionic low osmolar contrast media in this animal model of nephropathy.

Low Sodium Diet, Indomethacin, and Contrast Media

Urine profiles were followed for 3 or 9 days after intravenous injection of diatrizoate, iohexol, or saline in 30 adult Wistar rats, which received a low sodium diet for 14 days, and indomethacin intravenously 2 hours and immediately before contrast medium or saline injection. A control group of 10 rats, which also received low sodium diet, got saline alone and no indomethacin or contrast medium. Diatrizoate increased albuminuria during the first 22 hours after its injection whereas iohexol did not have any significant effect on albuminuria. Both contrast media caused tubular dysfunction, but there was significant difference between them during the first 2 hours after injection. Compared to the effect of saline, iohexol but not diatrizoate caused increased excretion of lactate dehydrogenase and N-acetyl-beta-glucosaminidase for 2 days. Iodine measurements showed delayed excretion of both media. Light microscopy showed focal location of dilated tubular profiles with hydrophia, which were only present in kidneys exposed to contrast media. It is concluded that in rats fed on a low sodium diet administration of indomethacin in relation to iohexol has a greater tubular cell effect than diatrizoate, which in turn has a greater effect on the glomerular permeability. The excretion of both media is delayed.

Effects of Intravenous Injection of Diatrizoate, Iohexol or Ioxilan on Renal Size, Urine Profiles and Blood Profiles in the Rabbit

Diatrizoate, iohexol or ioxilan were injected intravenously in 18 rabbits. The contrast medium passage through the kidneys was recorded on digital subtraction images for the first 50 s followed by 100 mm exposures up to 15 min after injection. The renal area was measured planimetrically. Urine profiles (glucose, phosphate, LDH, GGT, NAG), blood profiles (potassium, urea) and the relative clearance of albumin and sodium were followed for 5 days and compared with a control group injected with saline. All kidneys were examined by light and immunofluorescence microscopy. All three contrast media produced excellent arteriograms and urograms. The three different contrast media caused a rapid increase of the kidney area within the first minute, reaching an average maximum of 10 to 12 per cent after 5 min, followed by a gradual decline. Contrary to expectations the increase in renal area was similar for all three contrast media, so hyperosmolality is no likely explanation of this phenomenon. None of the contrast agents caused significant changes in any of the profile components with one exception: the GGT excretion was significantly elevated during the first 24 h after diatrizoate administration as compared with the effect of saline. Light and immunofluorescence microscopy revealed no differences.

Nephrotoxicity of Cyclosporin a and Contrast Media

Urine profiles (albumin, glucose, NAG, LDH, GGT and sodium) were followed for 22 h or 8 days after intravenous injection of diatrizoate, iohexol or saline in 30 adult Wistar rats in which nephrotoxicity was induced by daily peroral administration of 25 mg/kg body weight cyclosporin A over a 14-day period. Another 10 rats which had the vehicle of the cyclosporin A solution (placebo) and saline injected intravenously served as controls. The effect of iohexol and saline on the albumin excretion was similar, whereas diatrizoate increased it significantly. Both contrast media caused significantly increased excretion of all three enzymes. The contrast media had no effect on the excretion of glucose and sodium. Except for the fact that the excretion of NAG was significantly higher following iohexol than following diatrizoate 24 to 46 h after injection no significant differences between the two media were found from 24 h after injection among the rats given cyclosporin A. No contrast medium related changes were found by light microscopy of the kidneys. Neither iohexol nor diatrizoate potentiate acute cyclosporin A nephrotoxcity.

Effects on Urine Profiles of Diatrizoate in Hydrated and Dehydrated Rats

Effects of intravenous diatrizoate on urine profiles in hydrated and dehydrated rats were compared. In 12 normal rats albumin, glucose, sodium, and the enzymes LDH and GGT were followed twice over 3 hours. The 6 rats being dehydrated at the first examination were hydrated 28 days later and vice versa. At both examinations diatrizoate affected all profile components significantly during the first two hours and caused a 3 per cent weight loss in both groups. Only one significant difference between the hydrated and dehydrated rats was found: The excretion of the brush border enzyme GGT was 1.5 times higher in the dehydrated than in the hydrated rats in both series. Thus, the effect of diatrizoate on the tubular brush border seems to depend on the state of hydration in normal rats.

Using a dopamine type 1A receptor agonist in high-risk patients to ameliorate contrast-associated nephropathy

OBJECTIVE

The objective of our study was to evaluate the effects of fenoldopam mesylate, a dopamine type 1A receptor agonist and a potent renal vasodilator that markedly increases renal blood flow, on kidney function of patients who were receiving iodinated contrast material for an interventional procedure and thought to be at high risk of contrast-associated nephropathy.

MATERIALS AND METHODS

We retrospectively reviewed the records of all patients who received fenoldopam mesylate to determine the acute and, when possible, the longer term effects on kidney function.

RESULTS

Twenty-nine cases were reviewed. The average serum creatinine value before contrast administration was 2.55 mg/dL (range, 1.3-5.8 mg/dL) [corrected]. Twenty-four hours after contrast administration, serum creatinine was measured in 28 of the 29 patients. The serum creatinine values had decreased in 16 of the 28 patients by an average of 0.55 mg/dL [corrected]. In nine patients, the serum creatinine value had not changed. Two of the three increases in the serum creatinine value appear to have been caused primarily by problems that did not involve the contrast material.

CONCLUSION

The use of fenoldopam mesylate at appropriate doses offers patients at high risk for contrast-associated nephropathy a chance to avoid this complication. To learn the extent and true nature of the effect of fenoldopam mesylate in this patient population requires a rigorous scientific trial, which is currently underway.

Toward proteomics in uroscopy: urinary protein profiles after radiocontrast medium administration

Previous attempts to use urinary protein profiles for diagnostic purposes have been rather disappointing with respect to their clinical validity, in part because of the insufficient reproducibility, sensitivity, and rapidity of available techniques. Therefore, a newly developed, high-throughput technique, namely surface-enhanced laser desorption/ionization (SELDI) ProteinChip array-time of flight mass spectrometry, was studied, to assess its applicability for protein profiling of urine and to exemplify its use for a group of patients receiving radiocontrast medium. Assessment of the accuracy, sensitivity, and reproducibility of SELDI in test urinary protein profiling was performed. Renal function was studied in 20 male Sprague-Dawley rats before and after intravenous administration of either 1.25 g/kg ioxilan (n = 10) or hypertonic saline solution (n = 10) as a control. Urine samples from 25 patients undergoing cardiac catheterization were obtained before, immediately after, and 6 to 12 h after the procedure. Administration of ioxilan to rats resulted in changes in the abundance of proteins of 9.9, 18.7, 21.0, and 66.3 kD. For patients, even in uncomplicated cases of radiocontrast medium infusion during cardiac catheterization, perturbations in the protein composition occurred but returned to baseline values after 6 to 12 h. Proteins with molecular masses of 9.75, 11.75, 23.5, and 66.4 kD changed in abundance. For patients with impaired renal function, these changes were not reversible within 6 to 12 h. As a proof of principle, one of the peaks, i.e., that at 11.75 kD, was identified as beta(2)-microglobulin. SELDI is a promising tool for the detection, identification, and characterization of trace amounts of proteins in urine. Even for patients without renal complications, proteins with a broad range of molecular masses either appear in or disappear from the urine. Some of these might represent markers of impending nephropathy.

Effect of iomeprol on renal function immediately after abdominal angiography

PURPOSE

To investigate the acute renal effects of 2 osmolality levels of iomeprol in a double-blind, randomized, parallel-group study.

MATERIAL AND METHODS

Ten patients received iomeprol 300 mg I/ml, and a further 10 received iomeprol 400 mg I/ml intraarterially at routine abdominal angiography. The mean volume of contrast medium administered was 227.3+/-59.3 ml in the iomeprol 300 group and 221.5+/-30.9 ml in the iomeprol 400 group.

RESULTS

The urinary minute volume increased immediately after angiography, but tended to return to baseline 120 min after the examination. No significant decrease in creatinine clearance occurred; however, the fraction excretion of sodium increased immediately after angiography. The lysosomal enzyme N-acetyl-beta-glucosaminidase and the proximal tubular brush border enzyme gamma-glutamyl transferase increased up to 120 min after the procedure. Free water clearance was negative during each study period. No statistical differences in any parameter were evident between these 2 groups.

CONCLUSION

These results suggest that osmotic diuresis and its acute effect on proximal tubular function are induced by the administration of iomeprol, but that these changes are reversible.

Effects of contrast media on renal epithelial cells in culture

Proximal and distal tubular cells in culture have been exposed to various roentgen contrast media (CM) at concentrations of 0 to 100 mg I/ml for 22 hours to study cellular mechanisms that may be involved in CM-induced nephropathy. The effects on cell morphology were assessed by electron microscopy and cell viability was evaluated. Levels of brush border and lysosomal marker enzymes in the culture medium were assayed biochemically. Morphological examination showed that CM induced a concentration-dependent formation of large cytoplasmic vacuoles in both cell lines. Cellular damage was observed more frequently after exposure to low-osmolal rather than the iso-osmolal CM iodixanol; the low-osmolal CM causing more cell death and inhibiting cellular growth to a greater degree than did iodixanol. In cultures of both cell lines the CM produced a concentration-dependent increase in brush border marker enzyme activity. While an increase in lysosomal enzyme activity was seen at low concentrations, a decrease in activity occurred at high concentrations. Earlier investigations have demonstrated that the nonionic CM have less pronounced effects on the cell lines studied than ionic CM. The results presented here indicate that the effects of the iso-osmolal nonionic CM (iodixanol) on both the investigated cell lines are less marked than those of the low-osmolal nonionic CM investigated.