EFFECT OF POSTURAL CHANGES ON THE PHYSIOLOGICAL FUNCTION IN MAN

The hemodynamic responses and metabolic changes were examined in 13 healthy malestudents on the passive tilting from recumbency to 60°, 75° and 90° or vice versa, re-spectively. Abrupt increase of heart rate was observed by cardiotachograph on each ofpostural change. The average per cent increase in heart rate was about 50% as comparedwith that of recumbent, however, no significant difference was observed among each angle.Systolic pressure fell 15 mm Hg on tilting, but diastolic pressure remained at about thesame level. Urinary output of catecholamine, particularly of noradrenaline, increased markedly.The increased noradrenaline excretion may be attributed to the vasoconstriction, whichwas inferred from the reduction of amplitude in volume pulse in the big toe and from thefall in skin temperature. The rise of rectal temperature on tilting from recumbency totilt position may be attributed to both the decrease of heat loss through vasoconstrictionand the increase of heat production. On tilting urine volume and urinary output of sodium and chloride decreased, whilelittle change was observed in potassium excretion.