Published online Jan 21, 2019. doi: 10.3748/wjg.v25.i3.346
Peer-review started: October 30, 2018
First decision: November 14, 2018
Revised: December 12, 2018
Accepted: December 21, 2018
Article in press: December 21, 2018
Published online: January 21, 2019
Exposure to high sustained +Gz (head-to-foot inertial load) is known to have harmful effects on pilots’ body in flight. Although clinical data have shown that liver dysfunction occurs in pilots, the precise cause has not been well defined.
To investigate rat liver function changes in response to repeated +Gz exposure.
Ninety male Wistar rats were randomly divided into a blank control group (BC group, n = 30), a +6 Gz/5 min stress group (6GS group, n = 30), and a +10 Gz/5min stress group (10GS group, n = 30). The 6GS and 10GS groups were exposed to +6 Gz and +10 Gz, respectively, in an animal centrifuge. The onset rate of +Gz was 0.5 G/s. The sustained time at peak +Gz was 5 min for each exposure (for 5 exposures, and 5-min intervals between exposures for a total exposure and non-exposure time of 50 min). We assessed liver injury by measuring the portal venous flow volume, serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST), liver tissue malondialdehyde (MDA), Na+-K+-ATPase, and changes in liver histology. These parameters were recorded at 0 h, 6 h, and 24 h after repeated +Gz exposures.
After repeated +Gz exposures in the 6GS and the 10GS groups, the velocity and flow signal in the portal vein (PV) were significantly decreased as compared to the BC group at 0 h after exposure. Meanwhile, we found that the PV diameter did not change significantly. However, rats in the 6GS group had a much higher portal venous flow volume than the 10GS group at 0 h after exposure. The 6GS group had significantly lower ALT, AST, and MDA values than the 10GS group 0 h and 6 h post exposure. The Na+-K+-ATPase activity in the 6GS group was significantly higher than that in the 10GS group 0 h and 6 h post exposure. Hepatocyte injury, determined pathologically, was significantly lower in the 6GS group than in the 10GS group.
Repeated +Gz exposures transiently cause hepatocyte injury and affect liver metabolism and morphological structure.
Core tip: Some clinical data showed that liver dysfunction was observed in pilots. However, the reason was not clear. We conducted this experimental study to investigate rat liver function changes in response to repeated +Gz exposures, and to observe the portal venous flow volume, liver function indexes, liver tissue malondialdehyde, Na+-K+-ATPase activity, and changes in liver histology. We found that repeated +Gz exposures transiently cause hepatocyte injury and affect liver metabolism and morphological structure.