抄録
Introduction & Methods: We have reported that magnitude of reduction in arterial pressure at a level of the brainstem (APLB) is greater after stop of the anti-G suit operation than before start of the anti-G operation when exposed head-to-tail G by a centrifuge. To clarify the cause of the greater hypotension after stop of the anti-G suit operation, anesthetized male Sprague-Dawley rats were exposed to acceleration (3 and 5G). APLB, arterial pressure at a level of the lower body (APLL), central venous pressure, ECG, and aortic blood flow (AoBF) were measured. Peripheral vascular resistance (PVR) was calculated. Results: APLB was kept to the control level during inflation of an anti-G suit. However, hypotension was observed in G-increasing and -decreasing phases, and a significant difference was found between them. In the APLL, definite hypotension was observed only after inflation of the anti-G suit. AoBF and resultant PVR significantly decreased after than before the inflation (33.4±11.7 vs. 41.2±16.3 ml·min−1 and 0.98±0.45 vs. 1.15±0.42 mmHg·min·ml−1 ). Conclusion: No significant difference was found in the internal pressure of the anti-G suit or in loaded G between before and after the anti-G operation, but significant decrease was found in APLL and PVR after the anti-G operation, the vasoconstring responses to G loads should be suppressed. These results indicated that an anti-G suit might induce decline of peripheral vascular resistance after G loads. [J Physiol Sci. 2007;57 Suppl:S190]
