Comparative cytotoxicity of ionic and non-ionic radiocontrast agents on MDCK cell monolayers in vitro. (1/86)

BACKGROUND: Intravascular radiocontrast agents may cause acute renal failure, particularly in patients with pre-existing renal insufficiency. Direct cytotoxic effects of radiocontrast agents on renal tubular cells may contribute to the pathogenesis of radiocontrast-induced nephropathy. METHODS: We analysed the cytotoxicity of the ionic radiocontrast agents diatrizoate (monomeric) and ioxaglate (dimeric), as well as of the non-ionic radiocontrast agents iohexol (monomeric) and iodixanol (dimeric) on the renal epithelial Madin Darby Canine Kidney (MDCK) cell line grown on permeable supports. The toxicity assays assessed cell viability, transmonolayer resistance and inulin permeability between the apical and basal cell culture compartment. In addition, the distribution of the tight-junction-associated membrane proteins ZO-1 and occludin was analysed using immunofluorescence microscopy. RESULTS: In all assays the high osmolal ionic compound diatrizoate had significant cytotoxic effects that included the partial redistribution of the tight-junction-associated membrane proteins into a cytoplasmic compartment. To a lesser extent this redistribution also occurred with the dimeric ionic compound ioxaglate, but not with the non-ionic radiocontrast agents. With regards to cell viability, transmonolayer resistance and inulin permeability the radiocontrast agents with reduced osmolality were significantly less toxic than diatrizoate, independent of their ionic strength. CONCLUSIONS: Physicochemical factors contribute to the cytotoxicity of radiocontrast agents in vitro. The redistribution of tight-junction-associated membrane proteins by the ionic radiocontrast agents corresponds with the loss of the barrier function of the epithelial cell monolayer, which is a major pathophysiological mechanism in acute renal failure. The radiocontrast agents with reduced osmolality are less cytotoxic than diatrizoate, independent of their ionicity. Hyperosmolality appears to be a more important determinant of the cytotoxicity of diatrizoate than ionic strength.  (+info)

Effects of adenosine receptor antagonists on the responses to contrast media in the isolated rat kidney. (2/86)

Contrast media can induce both a decrease in renal blood flow and a reduction in glomerular filtration rate (GFR) when administered to both experimental animals and humans. In the present study we have examined the role of adenosine in mediating these effects using the isolated perfused rat kidney. Kidneys were perfused with a 6. 7%-(w/v)-albumin-based perfusate supplemented with glucose and amino acids (n=6 per group). They were exposed to diatrizoate [20 mg of iodine (mgI)/ml; osmolality 1650 mOsm/kg of water] or iotrolan (20 mgI/ml; osmolality 320 mOsm/kg of water) in the presence or absence of theophylline (10.8 microg/ml), or to diatrizoate in the presence or absence of a specific adenosine A(1) receptor antagonist (KW-3902; 2 microg/ml) or a specific A(2) receptor antagonist (KF17837; 6 microg/ml). Diatrizoate (n=6) produced a fall in GFR from 0.65+/-0.04 to 0.42+/-0.03 ml.min(-1).g(-1) (P<0.05); renal perfusate flow (RPF) also declined, from 36.5+/-3.8 to 22.0+/-3.2 ml. min(-1).g(-1) (P<0.05). Iotrolan (n=6) produced a fall in GFR from 0. 64+/-0.02 to 0.48+/-0.04 ml.min(-1).g(-1) (P<0.05) and in RPF from 33.3+/-3.8 to 24.0+/-3.0 ml.min(-1).g(-1) (P<0.05). Theophylline (10.8 microg/ml) prevented the fall in GFR caused by either diatrizoate (baseline, 0.63+/-0.05 ml.min(-1).g(-1); diatrizoate+theophylline, 0. 60+/-0.04 ml.min(-1).g(-1)) or iotrolan (baseline, 0.64+/-0.04 ml. min(-1).g(-1); iotrolan+theophylline, 0.67+/-0.05 ml.min(-1).g(-1)), but did not affect the decreases in RPF caused by either agent. KW-3902 (2 microg/ml) also prevented the fall in GFR produced by diatrizoate (baseline, 0.66+/-0.05 ml.min(-1).g(-1); diatrizoate+KW-3902, 0.61+/-0.05 ml.min(-1).g(-1)), while the fall in RPF remained unaffected. KF17837 (6 microg/ml) had no effect on the decreases in either GFR or RPF induced by diatrizoate (n=6 per group). The results suggest a role for adenosine acting at the A(1) receptor in mediating the decrease in GFR induced by contrast media. This effect is independent of a change in renal vascular resistance, and possibly secondary to mesangial cell contraction causing a decrease in the ultrafiltration coefficient.  (+info)

The effect of Hydrocortisone on the kinetics of normal human lymphocytes. (3/86)

Lymphocyte kinetic studies employing 51-chromium-labeled autologous lymphocytes were performed in nine normal volunteers in order to determine the effects of hydrocortisone administration on the recirculating versus the nonrecirculating intravascular lymphocyte pools. Following infusion of labeled cells, the recirculating portion of the labeled cells rapidly equilibrated with the total intravascular lymphocyte pool and the vastly larger total-body recirculating lymphocyte pool, so that by 1 hr following infusion 21.8% plus or minus 3.2% of the labeled lymphocytes were left in the circulation. Four hundred milligrams of intravenous hydrocortisone administered 24 hr after infusion of labeled cells caused a profound but transient lymphocytopenia which was maximal at 4 hr with return of lymphocyte counts to normal by 24 hr after injection. Concomitant with the lymphocytopenia there was a dramatic increase in lymphocyte specific activity (cpm per 10-6 lymphocytes), while the total lymphocyte-associated radioactivity remaining in the circulation was unchanged, indicating that corticosteroid administration depleted the unlabeled recirculating cells. As the lymphocyte counts returned to normal following hydrocortisone, the specific activity also returned to normal. These studies indicated that hydrocortisone administration caused a transient lymphocytopenia by a preferential depletion of the recirculating portion of the intravascular lymphocyte pool  (+info)

Lymphocytic Choriomeningitis virus. I. Concentration and purification of the infectious virus. (4/86)

Two procedures for the purification of infectious lymphocytic choriomeningitis virus from cell culture fluid have been developed. If large quantities of very pure virus are to be prepared, infected L cells are maintained with a medium supplemented with calf serum, the proteins of which have been largely removed by pretreatment with polyethylene glycol. Two days after infection of the cultures, the media are collected and the virus is concentrated by treatment with polyethylene glycol 40,000. Purification with a 10,000-fold increase of specific infectivity is achieved with steric chromatography on controlled-pore glass beads with pore sizes of 42 to 44 nm and centrifugation in density gradients prepared with amido trizoate. An alternative method begins with precipitation of the virus from infected cell cuture medium with zinc acetate, followed by controlled-pore glass chromatography and density centrifugation in a discontinuous sucrose gradient. Purification thus obtained is 200-fold in terms of specific infectivity.  (+info)

Role of NO in endothelin-regulated drug transport in the renal proximal tubule. (5/86)

We previously demonstrated in intact killifish renal proximal tubules that endothelin (ET), acting through an ET(B) receptor and protein kinase C (PKC), reduced transport mediated by multidrug resistance-associated protein 2 (Mrp2), i.e., luminal accumulation of fluorescein methotrexate (FL-MTX) (Masereeuw R, Terlouw SA, Van Aubel RAMH, Russel FGM, and Miller DS. Mol Pharmacol 57: 59-67, 2000). In the present study, we used confocal microscopy and quantitative image analysis to measure Mrp2-mediated transport of FL-MTX in killifish tubules as an indicator of the status of this ET-fired, intracellular signaling pathway. Exposing tubules to sodium nitroprusside (SNP), a nitric oxide (NO) donor, signaled a reduction in luminal accumulation of FL-MTX, which suggested pathway activation. N(G)-monomethyl-L-arginine (L-NMMA), an NO synthase inhibitor, blocked the action of ET-1 on transport. Because SNP effects on transport were blocked by bisindoylmaleide, a PKC-selective inhibitor, but not by RES-701-1, an ET(B)-receptor antagonist, generation of NO occurred after ET(B) receptor signaling but before PKC activation. NO generation was implicated in the actions of several nephrotoxicants, i.e., diatrizoate, gentamicin, amikacin, HgCl(2), and CdCl(2), each of which decreased Mrp2-mediated transport by activating ET signaling. For each nephrotoxicant, decreased FL-MTX transport was prevented when tubules were exposed to L-NMMA. ET-1 and each nephrotoxicant stimulated NO production by the tubules, as determined by a fluorescence-based assay. Together, the data show that NO generation follows ET binding to the basolateral ET(B) receptor and that, in activating the ET-signaling pathway, nephrotoxicants produce NO, a molecule that could contribute to subsequent toxic effects.  (+info)

Comparison of Triosil 370 with Urografin 76 and Hypaque 65 for coronary arteriography. (6/86)

Triosil 370 has been compared with Urografin 76, and Hypaque 65 by injecting identical volumes into the coronary arteries of human subjects in the course of coronary arteriography. The injection times used were the same and neither the patient nor the coronary artery catheter were moved between injections. The order in which the solutions compared were injected was alternated. The deviation in the ST segment and of the T wave which resulted from the injection was measured. The Triosil caused significantly less change than Urografin and Hypaque. A numerical expression of the T wave deflection derived from the data showed Triosil:Hypaque:Urografin equals I:2.6:2.9.  (+info)

Separation of spores and parasporal crystals of Bacillus thuringiensis in gradients of certain x-ray contrasting agents. (7/86)

Spores and parasporal crystals of Bacillus thuringiensis can be separated at moderate centrifugation speeds (10,000 to 12,000 rpm) in gradients of Renografin or sodium diatrizoate.  (+info)

Use of the tissue slice technique for evaluation of renal transport processes. (8/86)

A detailed discussion of the tissue slice technique for evaluation of transport phenomena is presented. Information is given concerning the preparation of tissue slices and the advantages of this procedure over corresponding in vivo techniques. In addition, the relationship of the in vitro renal transport of organic substances to in vivo renal function is discussed in detail. Finally, certain pitfalls related to in vitro slice transport studies are presented.  (+info)