Nephroprotective Potential of Ca and Mg against Cd and Pb in Rats * J. D. Dabak, S. Y. Gazuwa and G.A. Ubom Department of Biochemistry, Faculty of Medical Sciences, University of Jos,P.M.B. 2084, Jos, Nigeria. . INTRODUCTION Mining and smelting operation are important causes of heavy metals contamination in the environment due to activities such as mineral excavation, ore transportation, smelting and refining, and disposal of the tailings and waste water around mines [1, 2]. Adverse environmental impacts from excessive heavy metals dispersed from mines and smelter sites include contamination of water and soil, phytotoxicity, soil erosion and potential risks to human health [3, 4].Cd and Pb in the environment have been a concern since the 1960s when a painful bone disease itai-itai was reported to have been caused by Cd pollution in Japan [5] and Pb contamination of soil and sediment, and petrol in England was first reported by Davis and Holmes [6]. In larger doses Cd and Pb can accumulate in the liver and kidneys, and can replace Ca and Mg in bones and other organs leading to diseases [3, 7]. From an historical perspective, water quality and health management paradigms have evolved over the past several decades as our understanding of water quality issues and its health effects on humans increase [8]. This environmental pollution by Cd and Pb has raised growing concerns about their effects on the health of the general population since renal toxicity is one of the major problems identified [9]. From general knowledge, the primary function of the kidney is the excretion of body wastes and harmful chemicals including heavy metals. Large amount of cardiac output (one fourth) circulate through the kidney, the greatest rate of blood flow for any organ. This predisposes the kidney to heavy metal toxicity as the biological half-life of Cd and Pb is in the order of decades [10]. Exposure to high levels of Cd and Pb may cause kidney damage leading to renal failure [10, 9]. In our previous work, Ca and Mg were found to have hepatoprotective potential against Cd and Pb induced hepatotoxicity [11]. This made us ask the question: Could Ca and Mg also have nephroprotective potential against Cd ASIAN J. EXP. BIOL. SCI. VOL 3 (1) 2012: 214 - 221 © Society of Applied Sciences ORIGINAL ARTICLE ABSTRACT Keywords: Adverse environmental impacts from excessive heavy metals dispersed from mines and smelter sites include contamination of water, soil and phytotoxicity leading to potential risks to human health. One of the organs that are exposed to heavy metal toxicity is the kidney. In this study, concurrent administration of different combinations of Cd, Pb, Ca and Mg were carried out using a rat model to determine the nephrotoxicity of Cd and Pb, and also the nephroprotective potential of Ca and Mg against Cd and Pb. Studies indicate that the urinary excretion of Cd and Pb ions were increased as the concentrations of the combination of Ca and Mg were elevated thus: 0.0302±0.002, 0.0665±0.001, 0.0911±0.002, 0.2284±0.005, 0.0808±0.000 and 0.0246±0.001, 0.0095±0.002, 0.0881±0.0.003, 0.1037±0.003, 0.0940±0.000 respectively. The addition of either Cd or Pb salt alone without the addition of Ca and Mg salts show that the urinary excretion of Cd ions decreased as compared to control irrespective of the concentration of Cd or Pb salt added, while the Ca excretion increased as follow: 0.0302±0.002, 0.0163±0.002, 0.0144±0.000, 0.0122±0.002, 0.0131±0.000 and 8.0700±0.006, 14.6400±0.016, 10.3600±0.058, 16.1700±0.037, 21.8100±0.026 respectively. The biochemical and histopathological analyses show that Cd and Pb have nephrotoxicity, while Ca and Mg have nephroprotective potential against Cd and Pb in rats. This nephroprotection stems from the fact that the excretory pattern of the metals revealed that there exist mutual exclusivity between Ca/Cd, Ca/Pb, Mg/Cd, and Mg/Pb. Nephrotoxicity, Nephroprotective potential, Heavy metals, Environmental pollution, Mutual exclusivity. 2+ 2+ 2+ 2+ 214 ASIAN J. EXP. BIOL. SCI. VOL 3 (1) 2012