Abstract
Male rats of 80 weeks of age were divided into 2 groups, sedentary group (Group I, n-7) and exercise-trained group (Group II, n=8) . Rats in Group II were conditioned by a 4-weeks treadmill running program. These two groups and another group of male sedentary rats of 20 weeks of age (Group III, n-9) were all subjected to a Wiggers type hemorrhagic shock (mean arterial pressure of 30 torr. for 60 min.) . Pulse rate and pulse pressure during the shock experiment, acid-base balance indices and blood gas before and after the shock period, and survival rate within 7 days after the shock experiment were compared between the three groups.
Animals in Group I showed remarkably decreased pulse pressure during the shock period. Metabolic acidosis after the shock period in Group I was remarkable, resulting in a significantly higher mortality compared with Group III. In Group II, pulse pressure during the shock period was higher than in Group I. Metabolic acidosis after the shock period in Group II was less marked than in Group I, and mortality tended to be lowered in Group II.
These results indicated that physical training induced resistance to hemorrhagic shock in aged rats. One of the mediating mechanisms in this cross-adaptation between exercise and hemorrhagic shock may be changes in oxygen transport system.
