Effects of parabolic flight on abdominal arterial pressure in conscious rats.

Abdominal arterial pressure during parabolic flight was measured using a telemetry system to clarify the acute effect of microgravity on hemodynamics in conscious rats. The microgravity condition was elicited by three different levels of entry gravity, i.e. 2 G, 1.5 G and 1 G. On exposure to 2 G, mean aortic pressure (MBP) increased up to 118.7 mm Hg +/- 7.3 compared with the value at 1 G (107.0 +/- 6.3 mm Hg, n=6). The value at microgravity preceded by 2 G was 118.0 mmHg +/- 5.2 mm HG and it was still higher than at 1 G. When 1.5 G was elicited before microgravity exposure, MBP also increased (1.5 G: 114.9 +/- 5.3 vs 1 G: 105.8+/-5.0 mm Hg) and the value at microgravity was 117.3 + /- 5.3 mmHg. During pre-microgravity maneuver with 1 G, no changes were observed compared with the control level at 1 G (pre-microgravity: 105.0 +/- 5.0 vs 1G: 104.8 +/- 5.1 mm Hg ), whereas the MBP increased up to 117.0 +/- 6.5 mm Hg on exposure to microgravity. From these results, we found that in conscious rat MBP increase during acute microgravity exposure with either 1 G or hyper-G entry.