Parathyroid hormone-mediated aluminum deposition and egress in the rat.
Exogenous PTH significantly enhances tissue aluminum concentration in normal rats fed an aluminum-supplemented diet. In this study, we examined the effect of PTH withdrawal on brain and whole carcass aluminum concentrations. Four groups of rats were fed an aluminum diet while receiving injections of PTH for 5 days. On day 5, one group of rats was sacrificed, and the treatment regimen of the remaining groups altered. PTH, the aluminum diet, or PTH and the aluminum diet were withdrawn respectively for an additional 5 days. An additional group of rats was fed the aluminum diet for 10 days. PTH dramatically increased the concentration of aluminum in both brain and carcass above that found in tissues of rats given aluminum alone. Brain and whole carcass aluminum concentrations remained elevated in rats continued on PTH even in the absence of continued supplemental dietary aluminum. In contrast, following PTH withdrawal, brain and whole carcass aluminum concentrations were significantly lower and independent of dietary aluminum. Thus, PTH may be an important mediator of specific tissue aluminum burdens.