Cadmium-metallothionein-induced kidney dysfunction increases magnesium excretion in the rat

Urinary excretion of the major minerals, calcium (Ca), magnesium (Mg), sodium (Na), and potassium (K), as well as of protein and metallothionein, was studied following the injection of cadmium-metallothionein (CdMT) in rats. Animals were given vehicle (saline) and 0.4 and 0.8 mg Cd/kg body wt as CdMT. A marked, relatively early, and reversible increase in Mg excretion was seen. The increase was dose-related, indicating a close connection to the typical Cd-derived cellular damage in the renal tubular epithelium, including an early reversible Ca excretion and a late reversible protein excretion. The increase in Mg excretion was similar in magnitude to the one for Ca and much more prominent than that recorded for Na and K. The appearance of Mg and Ca excretion peaks at an early stage after CdMT injection makes it likely that this effect is an early event in the process of development of cellular damage and does not merely represent unspecific cellular damage giving rise to proteinuria.