Cellular Zinc Levels Research Articles

Plasma and cellular zinc levels and membrane lipid composition in streptozotocin diabetic rats

1. 1. Lipid and zinc analyses were conducted on liver mitochondrial and microsomal membranes as well as erythrocyte ghosts for streptozotocin (STZ) treated animals. 2. 2. In STZ animals, analysis of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) fatty acids revealed an increase in palmitic acid and a corresponding decrease in stearic acid. 3. 3. Polyunsaturated fatty acid were also affected, with an increase in 18:2, decrease in 20:4 and an increase in 22:6 in STZ animals compared to controls. 4. 4. The change in fatty acid composition was obsrved in all three membrane fractions. 5. 5. Plasma zinc levels in STZ animals were elevated while no difference was observed in membrane bound zinc. 6. 6. Thus, while there appears to be both altered trace metal as well as membrane lipid metabolism in STZ treated animals, membrane bound zinc does not seem to be affected.

Zinc status in children and young adults with sickle cell disease.

Previous studies have suggested an association of zinc deficiency and short stature in some children and adults with sickle cell disease (SCD). As a result, zinc supplementation has been recommended for these patients. The mechanism for zinc deficiency in certain patients with SCD is unknown, although renal loss of zinc has been suggested as a contributing factor. The zinc status of 29 subjects with SCD and 18 black controls was studied. No evidence of zinc deficiency in our population with SCD was found when plasma and cellular zinc levels were measured. Likewise, levels of two zinc-dependent enzymes, alkaline phosphatase and delta-aminolevulinic acid dehydratase, were normal in these subjects with SCD. Although adolescent subjects with SCD tended to be shorter than control subjects, there was no correlation between the height-forage z score and plasma zinc levels (r = -.31). It was concluded that zinc deficiency was not present in our population with SCD, and that there was no correlation between plasma zinc levels and the height-for-age z score in growing adolescent patients with SCD. These findings suggested that zinc supplementation may not be necessary in all patients with SCD.

Zinc suppression of free radicals induced in cultures of rat hepatocytes by iron, t-butyl hydroperoxide, and 3-methylindole.

The effect of zinc on lipid peroxidation initiated by either ferric-nitrilotriacetate, t-butyl hydroperoxide, or 3-methylindole was studied using primary monolayer cultures of rat liver parenchymal cells. The malondialdehyde content of the cells and culture medium was used to estimate the extent of lipid peroxidation. As the zinc concentration of the culture medium was increased from 1 to 48 microM, peroxidation was diminished. Cellular zinc and metallothionein levels were proportionally increased by supplemental zinc. Zinc supplementation of the medium inhibited NADPH-cytochrome c reductase activity and stimulated glutathione peroxidase activity. The uptake of iron into the hepatocytes was significantly reduced as the level of zinc was raised, suggesting that zinc antagonizes uptake of chelated iron into isolated hepatocytes and in this way blocks iron-induced peroxidation. Furthermore, induction of metallothionein synthesis by zinc may contribute to the reduction in free radicals. Spectra from electron spin resonance studies, using phenylbutylnitrone as a spin-trapping reagent, demonstrated that free radical production was inversely related to the zinc concentration of the culture medium. Spin trap data suggest that metallothionein added to lysed cells in vitro decreases free radical production. Studies using the spin trap, 3,3,5,5-tetramethylpyrroline-N-oxide indicated that cumulatively the predominant radical present in the cultures was a phenyl radical with hydroperoxide or methylindole. Collectively, our data demonstrate that zinc inhibits free radical production and lipid peroxidation in cultured hepatocytes. The mode of action of zinc could occur via free radical scavenging by zinc-induced metallothionein and/or by processes related to cytochrome P-450 and glutathione peroxidase, since these were also found to be sensitive to zinc supplementation levels of the culture medium.

Cellular zinc in patients with diabetes mellitus

Although hyperzincuria appears to be a common finding in most diabetic subjects, plasma zinc concentration has been reported to be normal, increased, or decreased in these patients. In this study we assayed cellular zinc levels of diabetic subjects in order to assess zinc status. Zinc levels in plasma, lymphocytes, granulocytes, and platelets were lower than in controls. We also observed hyperzincuria in our subjects. The activity of nucleoside phosphorylase a zinc dependent enzyme, was decreased in the lymphocytes. Based on these data we conclude that our diabetic subjects were zinc deficient.

Effects of trace metals on growth of red tide phytoplankton and their accumulation of metal.

The effects of six trace metals on the growth of five species of phytoplankton were examined and their uptake of these metals was investigated. Chattonella antiqua was sensitive to high cupric ion activities with a prolonged lag phase when the activity was 10™12,8m. The growth of Gymnodinium nelsoni was slowed by low manganese activities and stopped at the activity of 10“11 m. Thalassiosira sp., C. antiqua, and Heterosigma akashiwo were affected by low zinc ion activities and H. akashiwo was affected by low cupric ion activities. All species but Dunaliella sp. were affected by low iron concentrations. The cellular copper level of Dunaliella sp., the cellular manganese level of Thalassiosira sp., and the cellular zinc level of H. akashiwo were saturated. Thlassiosira sp. could accumulate about 32 times as much manganese as its minimum cell requirement.

Implications in the burn neutrophil of serum and cellular zinc levels

A parabolic correlation between leukocyte zinc content and phagocytic capacity apparent in clinical studies has been tested in a rat model. Dietary zinc restriction decreased average serum zinc levels from control values of 1.65 ± 0.41 to 0.70 ± 0.28 μg/ml during the first 13 weeks of restriction ( P < 0.0005) and to 0.56 ± 0.23 μg/ml during the second 13 weeks ( P < 0.0005). A parabolic variation in latex phagocytosis was observed in rat neutrophils during 33 weeks of zinc restriction. During study Weeks 12 through 21 a trend toward improved neutrophil antibacterial activity corresponded with a period of increased phagocytic activity in zinc-deficient rats. After Week 27 an opposite trend of impaired antibacterial activity corresponded to significantly decreased phagocytosis relative to controls ( P < 0.0005). This study suggests that acquired neutrophil functional defects may be corrected by replacement of specific nutritional components.

Alterations in cellular sodium, potassium, calcium, magnesium, copper and zinc levels during the development and maturation of erythrocytes in the rabbit.

SUMMARYThe levels of water, haemoglobin, sodium, potassium, calcium, magnesium, copper and zinc were estimated in a young population of macrocytic erythrocytes produced following the administration of phenylhydrazine, in a young population of normocytic erythrocytes, produced in response to repeated bleeding, and in a normal mixed population of erythrocytes in the rabbit.Compared with the normal mixed population of erythrocytes the average macrocytic erythrocyte contained, per cell, increased amounts of haemoglobin, water, potassium, magnesium, zinc, calcium, copper and a similar amount of sodium; per cu.μ of cell, increased amounts of water, potassium and calcium, reduced levels of haemoglobin and sodium, and similar levels of magnesium, zinc and copper; and per μl. of cell water, a decreased concentration of sodium which was accompanied by a reciprocal increase in the concentration of potassium.Compared with the normal mixed population of erythrocytes the average young normocytic erythrocyte contained, per cell, increased amounts of water, potassium and calcium, a decreased amount of sodium and similar amounts of magnesium, zinc, copper and haemoglobin; per cu.μ of cell, decreased amounts of haemoglobin and sodium, increased amounts of water and potassium and normal concentrations of magnesium, zinc and copper; and per μl. of cell water, a diminution in the concentration of sodium which was accompanied by a reciprocal increase in potassium.These results are discussed and it is postulated that these findings can be used to assess, indirectly, the chemical events that occur during the maturation of the erythrocyte precursors.