[Effect of contrast media on the structure and function of hepatocyte plasma membranes]. / Vliianie kontrastnykh sredstv na strukturu i funktsiiu plazmaticheskikh membran gepatotsitov.

The cholecystographic radiopaque agents, adipiodon and endographin, unlike the urographic contrast agents, triombrin and iodamide, decrease the fluorescence intensity of hydrophobic probes 1-anilinonaphthalene-8-sulfonate and 4-dimethylaminochalcone in plasmic membranes (PM) of rat hepatocytes primarily at the expense of the lowering of the constant of probe association with the membranes. The similar but less marked effects were discovered in experiments with lecithin lyposomal preparations. As regards the intensity of action, cardiotrast and triotrast an intermediate position between the two groups of radiographic contrast agents. Adipiodon and endographin induce an inhibition of membranous Mg+2 (Na+, K+) ATPase, which correlates with their effect on the structure of the hepatocyte PM. The data obtained allow a conclusion that, unlike the urographic agents, the cholecystographic radiopaque agents are bound to the definite areas of the hepatocytic PM and provoke alterations in the activity of membranous APTase because of the conformational rearrangements of the membranes.

[Effect of contrast media on the rate of oxidation of NADP.H and NAD.H by rat liver microsomes]. / Issledovanie deistviia rentgenokontrastnykh veshchestv na skorost' okisleniia NADF.H i NAD.H mikrosomami pecheni krys.

The effect of roentgen-contrast media on the activity of the NADP'N and NAD'N-dependent electron-transport chains of the rats liver microsomes was studied. Bilignost, cardiotrast, triiotrast and triombrin are shown to lower the rate of the NADP'N oxidation by the rats' liver microsomes and have no effect (except for triiotrast) upon the rate of the NAD'N oxidation. It is presumed that the relative resistance of the NAD'N-specific flavoproteid is due to the presence of a hydrophobic layer impervious to the polar molecules of the contrast media.

Activation of serum complement by contrast media.

Evidence is presented for the activation of serum complement by contrast media, in vitro and in vivo. Activation as a function of concentration was measured and the increasing order of effectiveness was found to be metrizamide, iothalamate, diatrizoate, acetrizoate, iodipamide and iopanoate. This order is the same as for protein binding and enzyme inhibition. The activation mechanism for iodipamide, and by inference for the other compounds, does not involve gamma-globulin aggregation. Serial daily injections in normal dogs resulted in substantial declines in serum complement over several days. Guinea pigs which were depleted of serum complement with cobra venom factor were found to be no less sensitive to lethal doses of iodipamide than those with normal complement. Implications of these findings are discussed.

[Study of interaction between contrast media and human serum albumin by the fluorescence method]. / Issledovanie vzaimodeistviia rentgenokontrastnykh vesh chestv s syvorotochnym al'buminom cheloveka metodom fliuorestsentsii.

Structural changes in the human serumal albumin under the effect of roentgen-contrast media, viz. bilignost, triiotrast, endografine, iodamide, triombrine and cardiotrast, were investigated by the method of fluorescence. The complex-formation of albumin with triiodotrast, bilignost and endografine was shown to call forth a short-wave shift of the fluorescence peak by approximately 20 nm. The binding section for these substances is characterized by an association constant equalling 1.2-10(5) M-1. The authors presume that triiodotrast, bilignost and endografine cause changes in the microstructure of the aqueo-protein layer in the area of the tryptophan residue localization. As to triombine, iodamide and cardiotrast fluorescence failed to disclose their combination with the human serumal albumin.