Effects of radiopaque contrast media on the microcirculation of the rabbit omentum.

Histamine concentration in plasma was measured and the microvasculature studied after injections of radiographic contrast materials and hypertonic NaCl solutions. Only 8 ml/kg of contrast material caused a prolonged decrease in systemic and microvascular pressure and a drop in erythrocyte velocity. Concomitantly, a significant increase in plasma histamine concentration was observed after two minutes. Signs of cellular defects and constriction of arterioles were noted after several minutes. These findings suggest that the hyperosmolality of the radiopaque materials tested could initiate the microhemodynamic reactions but is not responsible for cellular and endothelial damage in the microcirculation of the rabbit omentum.