[Adaptive and cumulative effects in the dog exposed to routine +GZ acceleration].

The development of adaptive and cumulative effects was investigated in 13 noninbred dogs regularly exposed to +GZ acceleration: Group I dogs were exposed 3 to 4 times a week for 2 months and Group 11 dogs were exposed 1 to 2 times a week for 5 months. The tolerance threshold was evaluated with respect to ECG abnormalities. The study of circulation reactions and acceleration tolerance threshold revealed the predominant development of adaptive changes that were more distinct in Group 11 dogs. Cumulative effects in the form of functional disorders of pulmonary vessels occurred in all experimental dogs but less frequently in Group II dogs. Morphological lesions of the lung tissue developed in Group I animals after 2 to 3 exposures and in Group II animals after 2 to 3 months, the incidence rate being lower in those latter. These findings suggest that adaptive and cumulative effects in response to regular exposures to threshold +GZ acceleration develop more or less in parallel.