In vitro andin vivo studies of radiographic contrast media-induced histamine release in pigs

Routine clinical use of radiographic contrast media (RCM) causes adverse reactions in some patients. To elucidate the mechanisms of these reactions bothin vitro andin vivo studies are necessary. In this study, RCM-induced histamine release from isolated mast cells was compared with thein vivo release of histamine and cardiovascular symptoms using a porcine model. The 2 non-ionic preparations examined (Solutrast^® and Ultravist^®) released little or no histamine from the 4 cell types tested (porcine pulmonary, cardiac, hepatic, and renal mast cells). The 4 ionic preparations (Angiographin^®, Hexabrix^®, Rayvist^®, and Telebrix^®) caused histamine release from most of the cell suspensions. In almost all cases, the cardiac mast cells were the most sensitive followed by the hepatic mast cells. All 4 RCM testedin vivo produced elevated plasma histamine levels in some animals. The highest incidence was observed using the ionic, high osmolal Rayvist^® (6 of 12 animals), followed by the non-ionic RCM with the lowest osmolality Ultravist^® (4 of 12 animals).In vivo, mechanisms in addition to direct histamine release may also be involved in RCM-induced adverse reactions, since low osmolal, non-ionic RCM can cause elevated plasma histamine levels withoutin vitro release. The susceptibility of cardiac mast cells to RCM-induced histamine release suggests that patients undergoing e.g. coronary angiography may be especially at risk for an adverse reaction.