The Role of Nuclear Factor of Activated T Cells 5 in Hyperosmotic Stress-Exposed Human Lens Epithelial Cells

We investigated the role of nuclear factor of activated T cells 5 (NFAT5) under hyperosmotic conditions in human lens epithelial cells (HLECs). Hyperosmotic stress decreased the viability of human lens epithelial B-3 cells and significantly increased NFAT5 expression. Hyperosmotic stress-induced cell death occurred to a greater extent in NFAT5-knockout (KO) cells than in NFAT5 wild-type (NFAT5 WT) cells. Bcl-2 and Bcl-xl expression was down-regulated in NFAT5 WT cells and NFAT5 KO cells under hyperosmotic stress. Pre-treatment with a necroptosis inhibitor (necrostatin-1) significantly blocked hyperosmotic stress-induced death of NFAT5 KO cells, but not of NFAT5 WT cells. The phosphorylation levels of receptor-interacting protein kinase 1 (RIP1) and RIP3, which indicate the occurrence of necroptosis, were up-regulated in NFAT5 KO cells, suggesting that death of these cells is predominantly related to the necroptosis pathway. This finding is the first to report that necroptosis occurs when lens epithelial cells are exposed to hyperosmolar conditions, and that NFAT5 is involved in this process.

The effect of iodine-based contrast agents on the levels of radiation-induced chromosomal aberrations

The effects of iodine-based contrast agents on the repair of radiation-induced chromosomal damage were investigated employing peripheral blood from a healthy male donor. The blood samples were irradiated with 0.5-4.0 Gy 137Cs gamma rays. Contrast agents and NaCl solutions of various concentrations were added to the blood within the first 15 min or at 60 min after irradiation, and the samples were subsequently cultured for 45 h at 37 degrees C. Significantly elevated frequencies of chromosomal abnormalities caused by postirradiation treatment with hypertonic contrast agents appeared to increase with increasing hypertonicity. Elevated aberration frequencies were found to be greatest in the samples treated within 15 min of irradiation. The contrast agents had little effect if they were added at 60 min after irradiation, probably because the process of chromosome rejoining had been completed. Isotonic iodine-based contrast agents did not enhance the frequencies of chromosomal aberrations to a significant degree.

Endothelial cell toxicity of preservation solutions: comparison of endothelial cells of different origin and dependence on growth state

Previously, we have shown that cultured liver endothelial cells are affected by an energy-dependent injury when incubated in cold University of Wisconsin (UW) or histidine-tryptophan-ketoglutarate solution. Here, we studied the susceptibility of other endothelial cells to this type of injury. Aortic endothelial cells in early-confluent, i.e., still proliferating, monolayer cultures were damaged more quickly during cold incubation in UW solution than during cold incubation in Krebs-Henseleit buffer. At this stage the addition of KCN did not alter the loss of viability in UW solution, but when the culture period was prolonged, cells were protected by the addition of cyanide. A paradoxical, protective effect of KCN could also be observed in late-confluent, i.e., nonproliferating, cultures of coronary endothelial cells incubated in UW solution. Similarly, liver endothelial cells in subconfluent, growing cultures were damaged by the addition of cyanide (loss of viability after 48 h, 3 +/- 1% in UW, 65 +/- 19% in UW + KCN), whereas in late-confluent cultures the addition of cyanide to UW solution was protective (loss of viability after 48 h, 100 +/- 0% in UW, 31 +/- 15% in UW + KCN). Variations of culture period and seeding density and the use of inhibitors of cell proliferation demonstrated that liver endothelial cells acquire their susceptibility to energy-dependent injury along with confluence. Subcultured cells retained this susceptibility for some hours. These results suggest that the energy-dependent injury described previously is not confined to liver endothelial cells and that the occurrence of energy-dependent injury requires a capacity of the cells that develops only after cultures have grown to confluence.

Acute pulmonary edema after over-infusion of crystalloids versus plasma: histological observations in the rat

An experimental model of acute pulmonary edema was obtained in the rat, with over-infusion of normal saline and of plasma: histology demonstrated essential differences between edema from crystalloids, developed in the interstitial space, and that from colloids, affecting the alveoli.

Flow cytometric analysis of organ preservation-induced endothelial cell membrane damage

Organ preservation for transplantation is associated with endothelial cell damage. This vascular injury results in increased capillary permeability, graft edema, and early graft dysfunction. This damage may be the limiting factor in preservation of these organs. This study uses flow cytometric assessment of membrane integrity to examine the effects of various organ preservation solutions on human umbilical vein endothelial cell cultures. Confluent plates of human umbilical vein endothelial cells were incubated at 4 degrees C for 24, 48, and 72 hours in commonly used preservation solutions. After cold incubation, the cells were harvested and stained with propridium iodide and fluorescein diacetate. Cells were examined using a flow cytometer for membrane integrity and cytosolic activity. When examined after 24, 48, and 72 hours, cells stored at 4 degrees C in a 5% polyethylene glycol salt solution were significantly less damaged than those stored in any other solution (p less than 0.05). After 48 and 72 hours at 4 degrees C, cells stored in ViaSpan were significantly more intact than cells stored in EuroCollins and 0.9% saline solution (p less than 0.05). This study demonstrates that endothelial cell damage occurs during cold storage and that a polyethylene glycol-based solution showed superior cellular preservation.

Endothelial cell toxicity of solid-organ preservation solutions

Endothelial cell damage caused by myocardial cardioplegic solutions (Bretschneider HTK and St. Thomas' Hospital No. 2) or renal and hepatic cold storage solutions (modified Collins and University of Wisconsin solution) was assessed in monolayer cultures of adult human venous endothelial cells at 4 degrees to 10 degrees C with phase-contrast microscopy. St. Thomas' Hospital solution caused the cells to contract, resulting in disruption of monolayer integrity and opening of intercellular gaps, and resulted in a 24-hour postexposure survival of 51.0% +/- 2.4%. Bretschneider HTK solution altered cellular morphology less and produced the best postexposure survival (80.2% +/- 2.6%; p less than 0.001). Although morphology was altered the least with University of Wisconsin solution, postexposure survival with this solution, which was similar to that with modified Collins solution, was superior to that with St. Thomas' (p less than 0.01) but inferior to that with Bretschneider HTK (p less than 0.05). The superior protection provided by Bretschneider HTK was due to its additives histidine, tryptophan, and KH-2-oxygluterate (p less than 0.005), and to its low chloride content (p less than 0.005). Furthermore, modifying St. Thomas' solution by decreasing its chloride content improved cell survival to 71.2% +/- 2.3% (p less than 0.001). Normothermic (37 degrees C) exposure to Bretschneider HTK, modified Collins, and University of Wisconsin solution was cytotoxic, whereas normothermic exposure to St. Thomas' cardioplegia was not. In conclusion, the preservation solution that is the least harmful to endothelial cells at hypothermia is Bretschneider HTK cardioplegic solution.

Functional endothelial damage by high-potassium cardioplegic solutions to saphenous vein bypass grafts

High-potassium cardioplegic solutions (CSs) may induce endothelial cell damage in vascular grafts, promoting graft thrombosis after coronary bypass operations. We studied prostacyclin (PGI2) production by saphenous veins as a marker of endothelial cell function in a model mimicking actual operative conditions. Fresh saphenous vein segments from patients who had undergone coronary bypass were cut in half; each part was perfused and incubated sequentially with CS (with 20, 40, or 80 mEq potassium/L) or a control buffer (5 mEq potassium/L) at 4 degrees C for 30 minutes (perfusion I), buffer at 37 degrees C for 15 minutes (perfusion II), and buffer plus 25 microM sodium arachidonate at 37 degrees C for 15 minutes (perfusion III). This permitted evaluation of changes in PGI2 production during or after exposure to CS, in basal and stimulated conditions. CS with 20 mEq potassium/L did not alter PGI2 production as compared with control buffer. CS with 40 mEq potassium/L decreased PGI2 production during perfusions I and II. CS with 80 mEq potassium/L also decreased sodium arachidonate-stimulated PGI2 production. Endothelial coverage (immunoperoxidase staining for factor VIII antigen) was intact at all potassium concentrations tested. Thus potassium in CSs can depress endothelial PGI2 production without causing immediate endothelial detachment. This effect may favor thrombosis in bypass grafts.

Studies on the increased potassium concentration of plasma produced by a hypertonic solution of low potent substances intraperitoneally administered to rats

Intracranial hemorrhage was induced in rats by low potent substances, glucose, NaCl and Na2SO4, intraperitoneally injected in enormous amounts, that is, 2800 mOsmol/L (J. Toxicol. Sci. 5, 290, 1980). The present study was undertaken to examine a mechanism of the above mentioned phenomenon in detail from the aspects of the disturbance of water-electrolyte balances and the change in blood osmolality. After administration of hypertonic solutions, blood and abdominal fluid were obtained at intervals of 5 to 15 min and at death. Hypertonic solutions injected intraperitoneally induced rapid exchange in water and solute across the peritoneum, thus causing an increase in abdominal fluid volume and plasma osmolality. Most interesting was the fact that a marked potassemia was produced and that the value of plasma potassium reached 10 mEq/L at death in all of groups of intraperitoneally injected rats. Thus, it is clear that the intracranial hemorrhage is accompanied by an increase in the plasma concentration of potassium which does not always run parallel with an increase in sodium concentration and osmotic pressure in rat plasma.

Response of the small intestine to the application of a hypertonic solution

The morphologic and functional alterations caused by a commonly used hypertonic radiographic dye (Hypaque(R)-50%) were compared with changes observed during the absorption of 150 mM saline in closed segments of the ileum of 2- to 3-kg rabbits. Hypertonic dye caused a rapid decrease in height and width of the villi, a decrease in height of the epithelial cells and closure of the intercellular space. Concomitantly, the tissue fluid content of the bowel wall and the volume of venous outflow from the segment of ileum decreased, presumably in response to the osmotic gradient between ileal lumen and blood. The fluid added to the luminal contents was hypotonic and contained sodium, potassium, chloride and bicarbonate. In contrast, the ileum exposed to 150 mM saline had prominent intercellular spaces between adjacent epithelial cells and absorbed the solution at isotonic conditions. These studies indicate that production of diarrheal fluid by this hypertonic solution is different from that reported for enteric pathogens.