The effect of age, species and adrenaline on the recovery of isolated atria from anoxia.

1. The rate of recovery of the force of contraction of isolated atria from different species of mature animals after 1 hour of anoxia was recorded.2. Atria from rabbits of different ages were also exposed to anoxia. Atria from rabbits, ranging in age from 8 days to 3 years, were essentially similar in their recovery from anoxia, which was significantly slower than that of atria taken from rabbit foetuses at the 25th day of gestation.3. Atria from human foetuses at 12-16 weeks of gestation recovered from anoxia much faster and more completely than any other atria studied and it is postulated that this may be due, in part, to the concentration of endogenous catecholamines being low.4. The addition of propranolol to the organ bath had no effect on the recovery of atria from anoxia but prevented the action of added adrenaline, which manifests itself in a slowing of the rate and incompleteness of the recovery.