Physiological Aspects of Aging

Rats representing two age groups (10 to 12 months and 22 to 32 months) were used in a study of the influence of aging on calcium metabolism. The endogenous excretion as well as intestinal absorption of calcium were observed to be significantly greater in the aged animals. The retention of calcium incorporated into the skeleton, measured by Ca45 labeling, was significantly poorer in the older group; however, both groups were found to be in overall calcium balance. These results indicate that the aged rats were subject to a greater loss of calcium from the body but were able to maintain calcium equilibrium by increasing the uptake of dietary calcium from the intestine.