抄録
Cardiovascular function is most vulnerable when exposed to high positive G acceleration in the z-axis (+Gz). The purpose of the sturdy is to evaluate cardiac micro-injuries on +Gz stresses. Anesthetized male SD rats were divided into three groups: control (CONT), +Gz exposure with an anti-G suit (WS), and +Gz exposure without an anti-G suit (WOS). Rats of the WS and WOS groups were exposed to +5Gz stress twice with 30-minute interval by the centrifuge. Arterial pressure level of the brainstem (APLB), heart rate and central venous pressure were recorded. Blood samples were taken three hours later after the second +Gz exposure. Plasma concentration of cardiac troponin T (cTnT) was measured by the electrochemiluminescence immunoassay technique. During +Gz exposure, severe hypotension was found in the WOS rats, while APLB was sustained in the WS rats. Plasma cTnT in the CONT, WS or WOS group was 0.086 ± 0.034, 0.502 ± 0.034 or 0.498 ± 0.076 ng/ml (mean ± SE), respectively. Plasma cTnT was significantly higher in both of the +Gz exposure groups than in the CONT group. No significant difference was found in plasma cTnT between the WS and WOS groups. +Gz stress caused severe hypotension in a brain level in the WOS rats, but not in the WS rats. The plasma cTnT concentration was increased by +Gz exposure in both of the WS and WOS groups. The result suggests that the +Gz stress per se may cause cardiac injury even when an anti-G suit functions well. [J Physiol Sci. 2008;58 Suppl:S110]
