The influence of non-ionic contrast media on the endothelium of small arteries. A comparison of metrizamide, iohexol and iopentol.

In 36 rabbits, small catheters were introduced into the central artery of one ear and into the saphenous arteries of both legs. Saline, metrizamide 170 mg I/ml, iohexol 137 mg I/ml and iopentol 137 mg I/ml, all solutions isotonic with blood, were tested. Perfusion with the test-solutions was performed with 2 ml x 3 at intervals of 5 min. In the case of iopentol, a dose-response study was performed, 1 ml x 3 and 4 ml x 3 being also tested. The solutions were administered under gentle pressure and at room temperature. Blood reflow was always observed between injections. All perfusates caused endothelial damage. Minor trauma led to endothelial cell contraction. More severe trauma increased the degree and numbers of contracted endothelial cells, frequently resulting in patches of denudation, sometimes the location for thrombus formation. In the control group only few effects on the endothelium were noted. Metrizamide caused more intimal damage at all times studied than either iohexol or iopentol. The immediate effects of saline and iopentol were quite identical, but at 2 h and 24 h iopentol caused much less intimal damage than saline.