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KMID : 0356219940250010059
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Journal of the Korean Military Medical Association
1994 Volume.25 No. 1 p.59 ~ p.67
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Effects of Supine Bedrest and Head-down tilt(-6°) on Plasma ADH, ANP and Renin Activity
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배재훈
민태형/박원균/채의업
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Abstract
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Background:
@EN This study was attempted to clarify the requlatory mechanism on endocrine responses including antidiuretic hormone(ADH), atrial natriuretic peptide(ANP) and plasma renin activity(PRA), and on central hemodynamic changes to supine bedrest and
-6°head-down tilt(HDT) as a model of simulated weightlessness.
@ES Methods:
@EN Ten healthy young males were participated in the two following postural tests: sitting 30 min and supine bedrest 180 min(SUPINE group) : sitting 30 min, supine 30min, HDT(-6°)120 min and supine 30min(HDT group). The changes of thoracic fluid
volume(TFV), cardiac index(CI), stroke index(SI) and heart rate(HR) were monitored by the impedance cardiograph. Arterial blood pressure(BP) and total peripheral resistance(TPR) were measured. The plasma levels of ADH, ANP and renin activity were
determined using the radioimmunoassay techniques.
@ES Results:
@EN Tilting from sitting to supine position in both SUPINE and HDT groups, TFV, CI and SI increased(p<0.05), and HR, BP, TPR decreased(p<0.05). During HDT(-6°), HDT group showed the significant decrease in CI and HR, and increase in TPR
compared
with
SUPING group. The endocrine results showed that the decreasing trend of ADH in SUPINE group. The endocrine results showed that the decreasing trend of ADH in SUPINE group, the increase of ANP in HDT group and the decrease in PRA in both groups in
comparision with sitting control value.
@ES Conclusion:
@EN This study shows that the decrease in PRA is only the consistent endocrine response to the postural changes from a sitting to supine bedrest and HDT(-6°) and there are the marked changes in hemodynamic parameters. Therefore, the postural
changes
elicite the regulatory process that is mainly adapted by the blood redistribution to the pulmonary and cephalic portions of the cardiovascular system than by the action of the endocrine system.
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KEYWORD
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