Cardiovascular aging in Syrian hamsters: similarities between normal aging and disease.

The functional status of the cardiovascular system in health and cardiomyopathic (CM) hamsters was assessed throughout their lives by measuring heart weight and fluid in the pleural and peritoneal cavities. An index of cardiovascular age was developed from a multiple regression model of changes in these variables with chronological age. This index showed parallel changes in healthy and CM hamsters with increasing age, but CM hamsters with shorter lifespans underwent the changes at earlier ages. It was also a better predictor of viability than chronological age. The cardiovascular age index correctly predicted the early death of those hamsters which died before the average death age, whereas they should have been alive according to their chronological age. Conversely, hamsters which lived beyond the average death age had cardiovascular ages younger than the average death age, whereas their chronological ages erroneously indicated they should have been dead. This index may have been able to assess viability because it was correlated with histopathological signs of congestive heart failure in both strains of hamsters, as well as with the total amount of pathology found in them. Hamsters which die naturally at a particular age should have older cardiovascular indices than those sacrificed at the same age, and CM hamsters which died at 11-13 months of age did have older cardiovascular ages than hamsters that were sacrificed at these ages. Three experiment examined the effects of various treatments on the index of cardiovascular age. Life in constant light decreased the cardiovascular age of CM hamsters by 30% and extended life by 25%. Chronic digitalis treatment will improve cardiovascular performance, and it prevented increases in cardiovascular age during the end stages of heart failure. Finally, life-threatening chronic stress increased cardiovascular age in CM hamsters, which suggested that severe stress brought CM hamsters nearer to death. However, it was not possible to determine whether the effects of these treatments were on aging or health. Thus, the data suggested that aging, at least in hamsters, may be closely related to the natural development of heart failure which represents a common end stage of life in both cardiomyopathic hamsters and very old, supposedly healthy hamsters.