Micro-gravity decreases barrier integrity, whereas hyper-gravity causes sustained and additive improvement of the endothelial barrier.

Representative time-course resistance measurements on confluent HUVEC monolayers at alternating intervals of A) 1g and micro-gravity (0.001g), B) 1g and hyper-gravity (2g), or C) 1g and 4g. Gray areas represent intervals of altered g-forces, whereas white areas indicate conditions of 1g. D) Comparison of EC gravity responses vs. static and rotational controls. Data were averaged (n = 4 per group) and presented as change in resistance referred to their baseline value at 0.00 minutes. Graphs to the right show quantifications of time until maximal resistance was reached, and the absolute change in resistance 30 minutes after application of g-forces. Significant differences between the groups are indicated and were calculated by 1-way ANOVA with Bonferroni corrected multiple comparison test.