[The external respiration parameters in an environment under excessive pressure].

In 21 alert rabbits staying for 1 hr in normoxic nitrogen-oxygen mixture under the pressure 6 kgs/cm2 and 1/2 hr respiration in air at atmospheric pressure, the increase in loading the respiratory system's muscles induced compensatory responses directed to preservation of the necessary level of lung ventilation. Total electrical activity enhances in the inspiratory muscles, and the pattern of separate motor units' discharges changes: firing rate increases, doubling and shift of discharges in the expiratory phase occur as well as alternation of activity in different motor units, recruiting of additional units, which seems to aid to the increase of the contraction force.