Laughlin M H, Witt W M, Whittaker R N
Aviat Space Environ Med. 1979 Nov;50(11):1129-33.
The two major factors limiting performance during high +Gz acceleration stress are loss of vision, and loss of consciousness. These symptoms are believed to occur as a result of insufficient blood flow to the retina and brain. This study was conducted to determine the effects of +Gz stress on regional cerebral blood flow. Cerebral blood flow (CBF) was measured in 22 conscious, female, miniature swine with the radio-labeled microsphere technique. Acceleration exposures consisted of 60-S plateaus at +3Gz, +5Gz or +7Gz. Microsphere infusions were made before, during, 1.0-6.0 min after, and 10 min after +Gz. Blood flow to the retina was significantly decreased during exposure to +5Gz and ceased during exposure to +7Gz stress. Mean, resting control CBF was 34 +/- 4 ml/min/100 g. Exposure to +3Gz and +5Gz had no significant effect on CBF. Exposure to +7Gz appeared to cause a redistribution of CBF, with blood flow to the brain stem being preserved and flow to the cerebrum being diminished.
在高+Gz加速度应激期间限制性能的两个主要因素是视力丧失和意识丧失。这些症状被认为是由于视网膜和大脑的血流不足所致。本研究旨在确定+Gz应激对局部脑血流的影响。采用放射性标记微球技术，对22只清醒的雌性小型猪进行脑血流（CBF）测量。加速度暴露包括在+3Gz、+5Gz或+7Gz下60秒的平台期。在+Gz之前、期间、之后1.0 - 6.0分钟以及之后10分钟进行微球注入。在暴露于+5Gz期间，视网膜血流显著减少，在暴露于+7Gz应激期间血流停止。静息对照时的平均CBF为34±4毫升/分钟/100克。暴露于+3Gz和+5Gz对CBF无显著影响。暴露于+7Gz似乎导致CBF重新分布，脑干血流得以保留，而大脑血流减少。
