Different sodium concentrations in fluids have variable impact on brain, lung and kidney damage in experimental ischemic stroke

BACKGROUND: Fluid administration is used many times in acute ischemic stroke (AIS). Controversies remain regarding the effect of different sodium concentrations in fluids administered after AIS as well as their impact on distal organ function. We aimed to compare the effects of four types of fluids [isotonic 0.9% saline (ISO), hypotonic 0.45% saline (HYPO), hypertonic 1.5% saline (HYPER) and glucose 5% (GLUCO)] on the perilesional areas of the brain, as well as on lung, and kidneys after AIS. METHODS: AIS was induced in 28 male Wistar rats and, after 3 hours, animals were randomized to receive one of the four types of fluids. RESULTS: In lung histology, ISO group showed less alveolar collapse, compared to HYPER (p=0.01) and less edema, compared to HYPO (p=0.007). ISO group presented lower interleukin (IL)-1ß expression in lung tissue compared to HYPO (p=0.027), whereas vascular endothelial growth factor (VEGF) and aquaporin (AQP)-5 were more pronounced in ISO, compared to GLUCO (p=0.0151 and p=0.0109, respectively). The brain histoarchitecture demonstrated an increase of versican and hyaluronan in ISO group compared to HYPER group (p=0.022 and p=0.018, respectively). HYPER group presented higher IL-1ß, vascular cell adhesion molecule-1 (VCAM-1) and zonula occludens (ZO)-1 expression in brain, compared to GLUCO group (p=0.01, p=0.02, p=0.006, respectively). IL1ßbrain expression was higher in ISO and HYPER than GLUCO (p=0.01). In kidney, ISO and HYPO groups induced less injury of the brush borders, compared to HYPER (p=0.007 and p=0.032, respectively). Neutrophil gelatinase-associated lipocalin (NGAL) renal expression was higher in GLUCO group, compared to HYPO (p=0.007). The chloride concentrations in blood samples decreased over time during experiments in ISO, compared to HYPO, HYPER and GLUCO groups (p=0.031, p=0.001 and p=0.021). HYPO group increased urine creatinine and osmolality, compared to HYPER (p<0.0001 and p=0.0027, respectively). CONCLUSION: Isotonic fluid causes less brain, lungs, and kidneys injury in experimental AIS.