Moreover, a positive correlation between Cd and Zn in urine was found in individuals exposed to low levels of Cd in the environment [28]. In this study, Mg administration had protective effect on Zn elimination via urine and kept it in the range of control levels. Since it is known that Mg is freely filtered by glomeruli and reabsorbed for almost 90% via paracellular selleck bio transport and in less extent (10%) by active transport, using TRPM6 channel [29, 30], it could be postulated that interactions between Mg and Zn could take place, at least partly, on glomerular filtrate level or on the level of reabsorption by paracellular route in the proximal tubule and in the thick ascending limb of Henle’s loop. Concerning their active transport, it is known that Zn uses different transporters such as ZnT and ZIP transporters which are highly specific [31] and are not proved to be influenced by Mg.
Divalent cation channel TRPM7 (transient receptor potential melastatin-related 7), which has very high affinity for Ca and Mg, is also implicated in Zn, as well as in Cd trafficking [32, 33]. However, question remains to what extent Zn can use these channels in conditions of Mg supplementation having in mind that they are strongly downregulated by intracellular levels of Mg2+, MgATP, and other Mg nucleotides [33]. The fact that Mg is applied as Mg acetate should be also taken into consideration since TRPM7 activity has been shown to be enhanced by acidic pH [30, 34].Cadmium caused increase of Zn concentration in liver and spleen and decrease in bone, which is in accordance with reports given for experimental animals as well as for humans [14].
Nevertheless, supplementation with Mg did not modify Zn concentration in all investigated tissues if compared with animals that received Cd. In both Cd and Cd + Mg groups, rise of Zn for more than 60% had occurred in liver where metallothioneins (MTs) are strongly induced by Cd. As Mg is not supposed to be either inductor of MT synthesis or to form complex with MT in vivo, it is most likely that Mg has no influence on the accumulation of Zn in liver. Supplementation with Mg even induced significant increase of pancreatic Zn if compared with Cd group and with controls suggesting that Mg favours Zn transfer into the pancreas.It is well established that Cd has potent influence on Cu body status in spite of stable Cu homeostasis [35, 36]. In this investigation, Cd intoxication induced significant increase of Cu in blood, provoked intensive urinary elimination of Cu, and elevated Cu concentration in kidney, muscle, GSK-3 pancreas, and spleen.However, Mg supplementation had profound effect on Cu status in Cd-exposed animals.
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