The G-tolerance after pharmacological hypohydration.

A group of 18 healthy male subjects (25-45 y.o.) participated in the studies of +8.3 Gx tolerance (profile of ballistic reentry) and +Gz tolerance (up to physiological limit) before and after pharmacological hypohydration of organism. Moderate hypohydration was carried out by one 40 mg Furosemid (Lasix) dose, or by pharmacological complex: Furosemid (40 mg) + Hypothiazide (25 mg) + Triamteren (50 mg). Subjects removed with urine about 2 l of water, that was accompanied by increase excretion of electrolytes and caused reduction of the body mass by 2.0 +/- 0.2% and diminution of the plasma volume by 13.5% +/- 2.0%. Pharmacological hypohydration does not lead to a substantial loss in +Gx tolerance. No pathological signs, limiting +Gx tolerance up to 8.3 g were found. The longitudinal +Gz tolerance was less, than +Gx one. The limit of achieved +Gz loads after diuretics reduced by 0.6 g. The scientific and applied significance of this research is that diuretics can be safety used in pre-launch period to prevent the negative effects associated with initial phase of space flight. Besides the preliminary intake of diuretics promotes to diminish of discomfort of cosmonauts, reducing urination in a period of prelaunch waiting in spacecraft.