[Tolerance of chest-to-back [+Gx] and head-to-feet [+Gx] acceleration in drug-induced hypohydration].

The effect of drug-induced hypohydration (furosemide, 40 mg per os) on the tolerance of chest-to-back (+Gx) and head-to-feet (+Gz) acceleration was investigated in 9 healthy male test subjects, aged 25-45 years. The test subjects were rotated in a 7.5 m arm centrifuge. The first exposure during which they were centrifuged at 4 G (+Gx and +Gz) served as a control. The second time they were exposed to centrifugation after diuretic administration. Prior to second exposure, the subjects showed increased diuresis (5.7 +/- 0.7 ml/min) and increased excretion of osmotically active compounds, including electrolytes. This led to a decrease of the circulating blood volume by 7.0 +/- 1.8% on an average. During centrifugation the following parameters were recorded: electrocardiogram, blood pressure in the arm and ear lobe vessels, ear pulsogram, and pneumogram. After diuretic intake +Gx tolerance remained essentially unchanged whereas +Gz tolerance was good but required greater efforts. It is concluded that moderate diuretic-induced hypohydration did not result in a drastic deterioration of acceleration tolerance.