Zinc content in islet cells of the mammalian pancreas in relation to the functional state of the insular system

Toroptsev, I. V.; Eshchenko, V. A.; Troshkin, V. G.

doi:10.1007/bf00809608

Cited by 9 publications

(6 citation statements)

References 2 publications

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“…These results were found in brain, but removal of ZnT3 from other tissues did not affect the chelatable vesicular zinc found. This occurs in the secretory granules of pancreatic ␤-islet cells (Toroptsev et al, 1974), salivary gland granular convulated tubule cells (Frederickson et al, 1987), germ cells of the testis (Danscher and Zimmer, 1978;Andrews et al, 1995), and cuboidal cells of the choroid plexus (Frederickson, 1989). These findings, within different tissues, appear to us to reinforce our hypothesis about the existence of different CVZ pools as occurs in development, since they suggest that an interaction between different protein complexes must be required in zinc vesicular transport.…”

Section: Expression Pattern Of Znt3 Compared With the Distribution Pasupporting

confidence: 76%

Developmental Expression of ZnT3 in Mouse Brain: Correlation between the Vesicular Zinc Transporter Protein and Chelatable Vesicular Zinc (CVZ) Cells. Glial and Neuronal CVZ Cells Interact

Valente

Auladell

2002

Molecular and Cellular Neuroscience

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Section: Expression Pattern Of Znt3 Compared With the Distribution Pasupporting

confidence: 76%

Developmental Expression of ZnT3 in Mouse Brain: Correlation between the Vesicular Zinc Transporter Protein and Chelatable Vesicular Zinc (CVZ) Cells. Glial and Neuronal CVZ Cells Interact

Valente

Auladell

2002

Molecular and Cellular Neuroscience

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“…ZnT3 is required for sequestration of zinc in synaptic vesicles of neurons, whereas removal of ZnT3 did not affect the histochemically reactive zinc found in secretory granules of pancreatic ␤-islet cells (29), salivary gland granular convoluted tubule cells (30), germ cells in the testis (31,32), or cuboidal cells of the choroid plexus (8). Other members of the ZnT family are likely to be responsible for compartmentalization of zinc in these and other cells.…”

Section: Discussionmentioning

confidence: 97%

Elimination of zinc from synaptic vesicles in the intact mouse brain by disruption of the ZnT 3 gene

Cole

Wenzel

Kafer

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

503

455

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The mammalian protein ZnT3 resides on synaptic vesicle membranes of zinc-containing neurons, suggesting its possible role in vesicular zinc transport. We show here that histochemically reactive zinc, corresponding to the zinc found within synaptic vesicles, was undetectable in the brains of mice with targeted disruption of the ZnT3 gene. Total zinc levels in the hippocampus and cortex of these mice were reduced by about 20%. The ultrastructure of mossy fiber boutons, which normally store the highest levels of vesicular zinc, was unaffected. Mice with one normal ZnT3 allele had reduced levels of ZnT3 protein on synaptic vesicle membranes and had intermediate amounts of vesicular zinc. These results demonstrate that ZnT3 is required for transport of zinc into synaptic vesicles and suggest that vesicular zinc concentration is determined by the abundance of ZnT3.

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“…We have shown that an increase in extracellular Zn 2+ decreases spike area, because more insulin escapes as dissolved complex, which is undetectable, and increases the spike width because the additional Zn 2+ slows the kinetics of dissolution and dissociation in canine β-cells . Vesicular Zn 2+ levels are 2.4-fold higher in mouse β-cells than in canine β-cells . Thus, it is likely that the Zn 2+ −insulin complex released from rodent β-cells dissociates more slowly due to an excess of Zn 2+ in the secretory vesicle thereby generating a lower concentration of free insulin monomer at the cell surface.…”

Section: Resultsmentioning

confidence: 96%

“…Thus, it is likely that the Zn 2+ −insulin complex released from rodent β-cells dissociates more slowly due to an excess of Zn 2+ in the secretory vesicle thereby generating a lower concentration of free insulin monomer at the cell surface. This idea is supported not only by the smaller area of the insulin spikes detected at mouse cells (Table ) but also by the observation that the mean width at half-height of insulin spikes from canine β-cells is 30 ± 1.3 ms ( n = 153) 24,25 whereas for the 12 current spikes detected from mouse β-cells the width at half-height was never less than 40 ms. Rat β-cells also have a higher level of Zn 2+ than canine β-cells, which may make insulin detection at rat β-cells difficult as well.…”

Section: Resultsmentioning

confidence: 99%

Comparison of Amperometric Methods for Detection of Exocytosis from Single Pancreatic β-Cells of Different Species

et al. 1999

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Two methods for amperometric detection of exocytosis at single pancreatic beta-cells were compared. In the first, direct detection of insulin was accomplished using an insulin-sensitive chemically modified electrode. In the second, 5-hydroxytryptamine (5-HT) that had been allowed to accumulate within the beta-cell secretory vesicles was detected with a bare carbon electrode. The goal of the comparison was to determine whether 5-HT secretion was a valid marker of insulin secretion in single beta-cells. To aid in this comparison, some experiments involved simultaneous measurement of insulin and 5-HT at cells previously allowed to accumulate 5-HT. Upon application of common insulin secretagogues, current spikes resulting from detection of 5-HT, insulin, or both compounds were obtained indicative of secretion via exocytosis. The mean area of current spikes obtained from simultaneous measurements equaled the sum of the mean area of insulin and 5-HT measured independently. Additionally, analyses of the number of spikes obtained for detection of insulin, 5-HT, or both compounds were similar for several common secretagogues. These data support the hypothesis that accumulated 5-HT is released from insulin containing secretory vesicles, exclusively. In addition, measurement of insulin and 5-HT from beta-cells of different species was compared to determine whether a species dependence exists for the two methods compared here. Detection of 5-HT results in a similar number of spikes that are equivalent to insulin in frequency and amplitude in human, porcine, and canine beta-cells; however, in mouse and INS-1 beta-cells, 5-HT is more readily detected than insulin.

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Zinc content in islet cells of the mammalian pancreas in relation to the functional state of the insular system

Cited by 9 publications

References 2 publications

Developmental Expression of ZnT3 in Mouse Brain: Correlation between the Vesicular Zinc Transporter Protein and Chelatable Vesicular Zinc (CVZ) Cells. Glial and Neuronal CVZ Cells Interact

Developmental Expression of ZnT3 in Mouse Brain: Correlation between the Vesicular Zinc Transporter Protein and Chelatable Vesicular Zinc (CVZ) Cells. Glial and Neuronal CVZ Cells Interact

Elimination of zinc from synaptic vesicles in the intact mouse brain by disruption of the ZnT 3 gene

Comparison of Amperometric Methods for Detection of Exocytosis from Single Pancreatic β-Cells of Different Species

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