Effect of radiologic contrast media on cell volume regulation in rabbit proximal renal tubules

Rationale and Objectives, Most radiographic contrast media are hyperosmotic and able to shrink cells with which they are in contact. The authors studied cell volume control in rabbit proximal renal tubules after incubation with three contrast media: iohexol, ioxaglate, and iodixanol. Materials and Methods. Proximal renal tubales were isolated from rabbit kidneys. The tubules were exposed to Ringer solutions containing 5% vol/vol iohexol (final osmolality, 330 mOsm), ioxaglate (323 mOsm), iodixanol (305 mOsm), or mannitol (control solutions with identical osmolalities), and tubule volumes were monitored. After 2 hours of incubation, the tubules were stimulated with a hyposmotic Ringer solution (165 mOsm). Three groups of 10 experiments were performed. Results. All solutions induced cell shrinkage (8.3% +/- 3.8 [standard error] to 15.4% +/- 0.5), which was completely or partly reversible in most experiments (volume increase, 44.8% +/- 14.7 to 149.9% +/- 107.3) but not those with iohexol and iodixanol, With exposure to the hyposmotic solution, the cells swelled by 11.0% +/- 1.8 to 39.7% +/- 4.8. In general, the tubules that had been exposed to the most hyperosmotic solution swelled the most. Those exposed to contrast media showed less swelling than the mannitol-exposed controls. In all control experiments, the cells exhibited a gradual shrink age (43.6% +/- 28.5 to 87.0% +/- 13). This regulatory response was partly inhibited in tubules exposed to iohexol (39.9% +/- 15.8 shrinkage) or iodixanol (8.9% +/- 15.8) and completely inhibited in those exposed to ioxaglate. Iohexol and ioxaglate exposure also led to a decrease in water permeability. Conclusion. Exposure to hyperosmotic contrast medium tends to induce prolonged cell shrinkage, decrease the water per meability of the cellular plasma membranes, and compromise the ability to regulate cellular volume. These changes seem to reflect both the hyperosmolality of the solutions and their inherent chemical properties.