Canine peripheral venous or suprarenal aortic injections of sodium or meglumine iothalamate produced a significant swing towards an alkaline urine only in individual dogs injected with meglumine salts. When mean values were compared for the sodium or meglumine groups as a whole, however, no significant differences could be established for pH change or induced diuresis. With both salts, ATPase inhibition could play a role in urinary electrolyte excretion. Carbonic anhydrase inhibition does not seem to play a significant role in urinary pH changes induced by contrast media.

Acetazolamide↗

PubMedDate not supplied

Contrast and electrolyte dynamics of the intravenous pyelogram. II. Disparities in serum and urine concentrations of meglumine and anion.

Intravenous or intra-aortic injections of meglumine iothalamate in dogs indicate a slightly different tissue distribution and excretory pattern of the meglumine cation and the iothalamate anion. Differences in serum and urinary concentrations of these ions suggest some cellular penetration of the meglumine anion. In addition, there seems to be some evidence for both tubular absorption and tubular excretion of meglumine as a minor component in the renal excretion of this ion. No significant differences could be demonstrated for either urinary load or concentration when the sodium salts of iothalamate were compared to the methylglucamine salts.

Animals↗

PubMedDate not supplied

Inhibition of adenosine triphosphatase and carbonic anhydrase by contrast media.

In vitro inhibition of adenosine triphosphatase and carbonic anhydrase by several radiographic contrast media and other compounds was measured. The concentrations required for 50% inhibition were, in general, similar to those obtained for other enzymes. The effect of methylglucamine could not be determined for either enzyme because of interference with the assays.

Acetazolamide↗

PubMedDate not supplied

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.

Acetrizoic Acid↗

PubMedDate not supplied

Research and research funding.

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National Institutes of Health (U.S.)↗

PubMedDate not supplied

Effect of endotoxemia on contrast media reactions.

Since complement activation is sharply temperature-dependent, we have examined the effects of fever produced by a very small dose of endotoxin on contrast media lethality in rabbits. After the injection of 8.2 ml/kg of 52% methylglucamine iodipamide, a group of rabbits exhibiting an average temperature elevation of 1.5 degrees C had a 100% mortality rate. This was contrasted to a 30% mortality in control rabbits receiving contrast alone, and no mortality in rabbits receiving endotoxin alone. The rabbits with fever and increased mortality exhibited increased activation of serum complement. From this preliminary data it appears that caution should be observed in performing a contrast examination in a patient with endotoxemia and/or a fever.

Animals↗

PubMedDate not supplied

Experiments with radiopaque perfluorocarbon emulsions for selective opacification of organs and total body angiography.

Emulsions of radiopaque perfluorocarbon with small particle size were prepared by sonication and concentrated by centrifugation. The emulsions were well tolerated when given intravenously to rats in a dose up to 20 ml/kg. Whole-body angiograms were obtained for up to 6 hours after injection with visualization of vessels smaller then 1 mm. Hepatosplenograms were obtained after 2 hours and for several days after injections of radiopaque perfluorocarbon. Contrast enhancement was also seen in the myocardium, ovaries, adrenal glands, and intestines with brominated perfluorocarbon emulsions.

Angiography↗

PubMedDate not supplied

Activation systems in contrast idiosyncrasy.

Both animal and human data suggest the possibility that the C1 esterase inhibitor may play an important controlling role in contrast media systemic reactions. This critical controlling protein has a major inhibitory effect on C1, kallikrein, activated factor XII of the intrinsic coagulation system, and on plasmin. In addition, it probably has other inhibitory effects not so well documented. Any circumstance that contributes to a continuing activation of the complement, coagulation, kinin, or fibrinolytic systems may result in partial consumption of the inhibitor and predispose the individual to adverse reactions to contrast challenge.

Anaphylaxis↗