Effects of radiographic contrast media on leukocyte locomotion.

It has been shown that radiographic contrast media activate the complement system and release C3A and C5A, which, among other things, are chemotactic factors; ie, they increase the locomotion of leukocytes. The authors have examined the effects of contrast media on plasma, serum, neutrophilic (polymorphonuclear) leukocytes, and several standard chemoattractant proteins using modified Boyden chambers and micropore filters. Contrary to the results of others, which showed that contrast media increased the locomotion of neutrophils toward standard chemoattractants, the authors have shown that contrast media uniformly reduced neutrophil locomotion towards chemoattractant proteins by a combined effect on the proteins and on the neutrophils themselves. The exact inter-relationship between reduction in neutrophil locomotion and any possible adverse effects of radiographic contrast media remains to be clarified.

The effect of ionic and nonionic contrast media on the metabolism of prostaglandin E2 in rat lungs.

Pulmonary inactivation of prostaglandin E2 (PGE2) was investigated in isolated perfused rat lungs during infusion of ionic and nonionic radiographic contrast media (RCM). When 100 nmol of [14C]-PGE2 was infused slowly into the pulmonary circulation, the ionic ioglycamate decreased the metabolism of PGE2, but other ionic (diatrizoate and ioxaglate) and nonionic RCM (iopamidol and metrizamide) had no significant effect. When a smaller amount of [14C]-PGE2 (10 nmol) was injected as a bolus the metabolism of PGE2 was decreased also by diatrizoate and ioxaglate, but not by iopamidol. After a similar bolus injection of 10 nmol of [14C]-PGE2, the efflux of radioactivity from the lungs was increased by diatrizoate, ioglycamate and ioxaglate but remained unchanged by iopamidol and metrizamide. The RCM infusion did not change the perfusion pressure. The present study indicates that ionic RCM decrease the inactivation of PGE2 in rat lungs and thus possibly increase the circulating level of this prostaglandin.

The effects of radiographic contrast media on leucocyte orientation.

The effects of radiographic contrast media (RCM) on leucocyte orientation in vitro were studied using a Zigmond chamber. Leucocyte orientation was assessed following exposure of the leucocytes to iotrolan, iohexol, ioxaglate and diatrizoate. The RCM used were diluted to a concentration similar to that obtained in vivo during routine angiography. At this concentration there was a significant reduction in leucocyte orientation for all RCM investigated but the effect was more pronounced in the monomeric than the dimeric RCM. The results may have significance when deciding which radiographic contrast medium to use in selected patients, particularly those who are immunosuppressed or septicaemic.

Ioglycamide induced release of testosterone and estradiol from protein bound stores.

With the use of an aqueous two-phase system the effect of ioglycamide (Bilivistan) on the binding of testosterone and estradiol to albumin and testosterone-estradiol-binding globulin was investigated using whole human serum. Reduced binding capacity was recorded for TeBG and a reduced apparent association constant for the testosterone-albumin binding was recorded in the presence of ioglycamide in high concentration. The significance of reduced binding of testosterone and estradiol to albumin and TeBG was discussed in relation to side-effects of radiographic contrast media.

Effect of ioglycamide (Biligram) on bile flow and biliary lipid secretion in man.

Twenty-one anicteric patients with a t-tube in situ were studied between the ninth and 11th postoperative days. Eleven patients were given an intravenous infusion of the biliary contrast agent ioglycamide (Biligram), while the other 10 acted as controls. Bile flow was recorded and the biliary concentrations of ioglycamide, bile salt, phospholipid, and cholesterol estimated in the two groups. The biliary excretion of ioglycamide was associated with a significant choleresis which was probably due to the obligatory coupling of the osmotically active contrast agent molecules with water. Biliary ioglycamide excretion did not significantly alter bile salt secretion rates. In contrast, the biliary secretion of both phospholipid and cholesterol was significantly lowered (P less than 0.001). Unlike chenodeoxycholic acid, ioglycamide significantly reduced bile acid independent cholesterol secretion (P less than 0.01), although secretion rate in terms of mumol of bile acid was essentially unchanged.

[Mechanisms of bile secretion in mini-pigs (author's transl)]. / Zur Physiologie der Galleexkretion beim Zwergschwein

The mechanisms of bile excretion are investigated in 27 experiments in 21 mini-pigs. The results confirm the known three fractions of bile flow for mini-pigs, too: a canalicular bile acid dependent, a canalicular bile acid independent and a ductular bile acid independent bile flow. These different fractions of bile flow may be stimulated either by taurocholate, by phenobarbital and ioglycamide or by secretin and pancreozymin. The total bile acid pool amounts 4,4 mMol. Measurements of its distribution over the gallbladder and the enterohepatic circulation after fasting for 18-24 hours emphasize the importance of the gallbladder resp. the fasting as factors that may be responsible for the secretion of lithogenic bile.

Release of protein bound progesterone in human serum by ioglycamide.

With the use of an aqueous two-phase system the influence of ioglycamide on the serum protein binding of progesterone was investigated. Ioglycamide was found to cause a decrease in the association constants for the binding of progesterone to both albumin and transcortin. The binding capacity for the progesterone binding to transcortin was also decreased. The decreased progesterone binding was discussed in terms of clinical relevance in connection with adverse reactions at cholegraphy with intravenous injection of ioglycamide.

Activation of complement by radiographic contrast media: generation of chemotactic and anaphylatoxin activities.

Iodinated radiographic contrast media such as methylglucamine diatrizoate and sodium ioglycamate activate serum complement in vitro. This was shown by a dose-, time-, and temperature-dependent decrease of total hemolytic complement activity in normal human serum, consumption of C4 and C6 activity, conversion of C3 to C3b, and generation of C5-derived chemotactic and smooth muscle contracting activity. Complement activation was achieved even in sera depleted of immunoglobulin and properdin, which may indicate that contrast media induce complement activation by mechanisms different from the classical or alternative pathway.

Effects of ioglycamide on the hepatic transport of bilirubin and its mono- and diconjugates in the rat.

Bilirubin seems to share the biliary excretion pathway with other organic anions, but not with bile acids. We studied the effects of the organic anion ioglycamide, an iodinated contrast agent, on bilirubin metabolism in Wistar rats. This compound does not undergo conjugation and is characterized by a maximal biliary secretory rate (Tm). The results show that in spite of producing a 3-fold increase in bile flow, ioglycamide excretion under Tm conditions decreased the output of unconjugated bilirubin and its monoconjugate by approximately 90%. Diconjugated bilirubin decreased by only 50% and became by far the predominant pigment in bile (86.5 +/- 6.0% of total pigment vs. 61.0 +/- 4.0% in basal conditions, n = 12). Unconjugated and monoconjugated bilirubins changed in parallel suggesting that the former arises from the monoconjugates. In serum, diconjugated bilirubin augmented from trace amounts to 1.15 +/- 0.17 mumole per liter. Total conjugated pigments in serum increased from 5 to 85% of total bilirubin. Bile acid output remained unchanged. Pretreatment of rats with ioglycamide altered neither the activity of bilirubin UDP-glucuronyltransferase nor the ratio of diconjugate to monoconjugate formed at both low (25 microM) and high (164 microM) bilirubin concentrations. The observed biological effects of ioglycamide were dose-dependent and fully reversible. We suggest that ioglycamide interferes with the excretion of conjugated bilirubins ("bilirubinostasis"). The monoconjugates retained in the hepatocyte might then undergo more efficient transformation to diconjugates, the latter thus becoming the most important bile pigments in serum and bile.