The role of aluminum in the development of hypercalcemia in the rat.
The present study evaluates the effect of an intravenous (i.v.) aluminum infusion on total and ionized calcium. Seven groups of rats were studied, and it was found that the magnitude of hypercalcemia was dose dependent. During a two hour i.v. infusion containing 0.4 mg aluminum per 100 grams of body weight, the total plasma calcium increased from 9.7 +/- 0.2 to 12.7 +/- 0.7 mg/dl (X +/- SE, P less than 0.02) while the ionized calcium decreased from 5.1 +/- 0.12 to 4.05 +/- 0.24 mg/dl (P less than 0.001). The increase in plasma calcium occurred in intact and parathyroidectomized rats, and the hypercalcemia could not be attributed to changes in PTH, arterial pH, plasma protein, or plasma phosphate. In vitro studies indicate that the addition of aluminum to rat plasma results in decreased ionized calcium concentration. Similarly, ultrafilterable calcium declined from 5.4 +/- 0.17 to 4.53 +/- 0.12 mg/dl (P less than 0.001) after the addition of aluminum to rat plasma. In summary, high levels of intravenous aluminum increase total plasma calcium and decrease ionized calcium. As also supported by in vitro data, the most probable mechanism is increased binding of calcium in the plasma which decreases ionized calcium. As a result of the decreased concentration of ionized calcium, movement of bone and interstitial calcium into the vascular space may occur, thus increasing total plasma calcium.
D000535:Aluminum / Q000097:blood / Q000494:pharmacology / Q000633:toxicity*; D000818:Animals; D001769:Blood; D001798:Blood Proteins / Q000378:metabolism; D002118:Calcium / Q000097:blood; D006863:Hydrogen-Ion Concentration; D006934:Hypercalcemia / Q000139:chemically induced*; D008297:Male; D010280:Parathyroid Glands / Q000502:physiology; D010530:Peritoneal Dialysis; D010710:Phosphates / Q000097:blood; D051381:Rats; D011919:Rats, Inbred Strains
D001798:Blood Proteins; D010710:Phosphates; D000535:Aluminum; D002118:Calcium