Decreases of calcium and phosphorus in monkey cardiac walls with development and aging.

To elucidate compositional changes of the cardiac walls with development and aging, the authors investigated changes of elements in the atrial and ventricular walls of monkeys. The left and right atrial walls, left and right ventricular walls, and interatrial and interventricular septa were resected from the subjects. The subjects consisted of 17 rhesus and 13 Japanese monkeys, ranging in age from 10 d to 33 yr. The element content of the cardiac walls was analyzed by inductively coupled plasma-atomic emission spectrometry. The Ca and P contents decreased in all of the left and right atrial and ventricular walls, interatrial septa, and interventricular septa with development, whereas the S and Mg contents decreased in the left and right ventricular walls with development. Regarding the relationships among elements, significant direct correlations were found among Ca, P, Mg, and Zn in all of the left and right atrial walls, left and right ventricular walls, and interatrial and interventricular septa, with some exceptions. As Ca decreased in the cardic walls, P, Mg, and Zn decreased simultaneously in the cardiac walls. The mass ratio of Ca/P decreased gradually with Ca decrease in both the atrial and ventricular walls, but it was not constant.

Age-related attenuation in the elements in monkey sino-atrial node.

Changes in trace elements of the sino-atrial (SA) node with aging was investigated using 24 hearts of the Japanese and rhesus monkeys of ages ranging from 27 d to 30 yr. With aging, sympathetic activity decreases and SA nodal function deteriorates. The SA nodal tissue was removed from the anatomical position and was confirmed by means of histological observation. The elements, such as Ca, P, S, Mg, Na, Fe, and Zn, were analyzed using inductively coupled plasma-atomic emission spectrometry (ICP-AES). Advancing age never increased the contents of the trace elements, but decreased them. The correlation coefficients for the age-dependent attenuations were -0.561 (n = 24, p < 0.01) in Ca and -0.482 (n = 24, p < 0.05) in P. The correlations for the attenuations induced by other trace elements were not significant. Furthermore, close relationships of the elements between Ca and P, S, Zn, or Na contents, between P and Zn or Na contents, and between Zn and Na contents were observed. These results indicate that the elements in the monkey SA node are attenuated with an increase in age, presumably suggesting the age-related suppression of cardiac functions as a result of the histological alterations of the SA nodal cells.