Calcium-dependent injury of human microvascular endothelial cells induced by a variety of iodinated radiographic contrast media

Rationale and objectives: The aim of the present study was to determine the possible mechanisms underlying the endothelial cell damage induced by iodinated radiographic contrast materials (RCM). Methods: The cultured human skin microvascular endothelial cells (HMVECs) were exposed to various contrast media, and the cell viability was measured by mitochondrial enzyme activity. Nuclear damage was assessed by Hoechst 33342 staining and a fluorescent single-cell gel electrophoresis. The effects of contrast materials on the cellular ATP content and intracellular free Ca²⁺ concentration were subsequently examined. Results: Although the iodinated RCM tested all caused the cell injury in HMVECs, ionic RCM including amidotrizoate and ioxaglate were more potent in producing the cell damage than nonionic RCM. It is unlikely that the contrast material-induced cell damage is associated with hyperosmolality, since hyperosmolar solution of mannitol or NaCl had no marked influence on the endothelial cell viability. Nuclear damage was noted in cells exposed to amidotrizoate. Amidotrizoate lowered cellular ATP content while elevating the intracellular free Ca²⁺ concentration. It was notable that the RCM-induced endothelial cell damage was reversed by the chelation of intracellular Ca²⁺ with 1,2-bis(o-aminophenoxy)ethane- N,N,N′,N′-tetra-acetic acid but not by the removal of extracellular Ca²⁺. Conclusions: Both ionic and nonionic contrast materials caused nuclear damage of endothelial cells. The decrease in tissue ATP content and elevation of intracellular Ca²⁺ are likely to contribute to the contrast materials-induced endothelial cell damage.