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ALUMINUM ALTERS CALCIUM TRANSPORT IN PLASMA MEMBRANE AND ENDOPLASMIC RETICULUM FROM RAT BRAIN
Citation:
Mundy, W., P. Kodavanti, V. Dulchinos, AND H. Tilson. ALUMINUM ALTERS CALCIUM TRANSPORT IN PLASMA MEMBRANE AND ENDOPLASMIC RETICULUM FROM RAT BRAIN. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-94/200 (NTIS PB94163797), 1994.
Description:
Calcium is actively transported into intracellular organelles and out of the cytoplasm by Ca2+/Mg2+-ATPases located in the endoplasmic reticulum and plasma membranes. he effects of aluminum on calcium transport were examined in the adult rat brain. 5Ca-uptake was examined in microsomes, and Ca2+-ATPase activity was examined in microsomes and synaptosomes isolated from the frontal cortex and cerebellum of adult male Long-Evans rats. TP-dependent 45Ca-uptake was similar in microsomes from both brain regions. he addition of 50-800 uM AlCl3 resulted in a concentration-dependent inhibition of 45Ca-uptake. g2+-dependent Ca2+-ATPase activity was significantly lower in synaptosomes compared to microsomes in both frontal cortex and cerebellum. n contrast to the uptake studies, AlCl3 stimulated Mg2+-dependent Ca2+ATPase activity in both microsomes and synaptosomes from both brain regions. o determine the relationship between aluminum and Mg2+, ATPase activity was determined in the presence of increasing concentrations of Mg2+. hen AlCl3 was substituted for Mg2+, ATPase activity was also stimulated in a concentration-dependent manner, but to a greater extent than with Mg2+. ne interpretation of these data is that aluminum acts at multiple sites to displace both Mg2+ and Ca4+, increasing the activity of the Ca2+ATPase, but disrupting transport of calcium.