Age-dependent changes of elements in human trachea.

To elucidate compositional changes of human trachea by aging, element contents in tracheae were determined by inductively coupled plasma-atomic emission spectrometry. The subjects consisted of seven men and seven women, ranging in age from 61 to 97 yr. The sulfur content of the tracheae decreased gradually with aging. In regard to calcium and phosphorus, both the contents increased to about threefold amounts in their seventies compared with those in their sixties, and decreased thereafter. The contents of calcium and phosphorus were the highest in their seventies. Therefore, it is likely that surplus calcium released from bones is deposited temporally in the trachea, and the deposits are released from the trachea at older age. Based on our results of human cartilages, there are two types in regard to calcium accumulation: The first type is that calcium accumulation occurs progressively with aging; the second one is that calcium accumulation becomes the highest in the seventies or eighties, and decreases thereafter. Therefore, the trachea belongs to the second type. Furthermore, the magnesium content remained constant through the age range.