Fig. 3. Microgravity promoted formaldehyde generation by affecting intracellular Ca2+ and FA metabolism in vitro.

a Simulated microgravity model of human SH-SY5Y cells in a rotary cell culture system. C-SM: simulated microgravity in the cultured cells. b, c Mitochondrial or cytoplasmic formaldehyde and intracellular Ca²⁺ detected by confocal imaging. Scale bar = 30 μm. d–f Statistical analysis of cellular Ca²⁺ influx, mitochondrial formaldehyde, and cytoplasmic formaldehyde (n = 18). 8 h: 8 h. g Cell model of the effects of the different medicines on FA metabolism and intracellular Ca²⁺ levels. FA formaldehyde, SSAO semicarbazide-sensitive amine oxidase, SARDH sarcosine dehydrogenase, BEN benzylamine, MA methoxyacetic acid, SA sarcosine, SEM semicarbazide, VER verapamil. h, i Changes in the levels of intracellular Ca²⁺ and FA in the cultured HAECs after different medicines treatments, respectively. HAECs human aortic endothelial cells. j, k Changes in the activity of SSAO and FDH in the cultured HAECs. (Repeated three times). Error bars show the mean ± SEM; *p < 0.05, **p < 0.01, ***p < 0.001.