Secretory state regulates Zn2+ transport in gastric parietal cell of the rabbit

Haley B. Naik, Melissa Beshire, Breda M. Walsh, Jingjing Liu, David I. Soybel

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Secretory compartments of neurons, endocrine cells, and exocrine glands are acidic and contain high levels of labile Zn2+. Previously, we reported evidence that acidity is regulated, in part, by the content of Zn 2+ in the secretory [i.e., tubulovesicle (TV)] compartment of the acid-secreting gastric parietal cell. Here we report studies focusing on the mechanisms of Zn2+ transport by the TV compartment in the mammalian (rabbit) gastric parietal cell. Uptake of Zn2+ by isolated TV structures was monitored with a novel application of the fluorescent Zn 2+ reporter N-(6-methoxy-8-quinolyl)-para-toluenesulfonamide (TSQ). Uptake was suppressed by removal of external ATP or blockade of H +-K+-ATPase that mediates luminal acid secretion. Uptake was diminished with dissipation of the proton gradient across the TV membrane, suggesting Zn2+/H+ antiport as the connection between Zn2+ uptake and acidity in the TV lumen. In isolated gastric glands loaded with the reporter fluozin-3, inhibition of H+-K +-ATPase arrested the flow of Zn2+ from the cytoplasm to the TV compartment and secretory stimulation with forskolin enhanced vectorial movement of cytoplasmic Zn2+ into the tubulovesicle/lumen (TV/L) compartment. Our findings suggest that Zn2+ accumulation in the TV/L compartment is physiologically coupled to secretion of acid. These findings offer novel insight into mechanisms regulating Zn2+ homeostasis in the gastric parietal cell and potentially other cells in which acidic subcellular compartments serve signature functional roles.

Original languageEnglish (US)
Pages (from-to)C979-C989
JournalAmerican Journal of Physiology - Cell Physiology
Volume297
Issue number4
DOIs
StatePublished - 2009

All Science Journal Classification (ASJC) codes

  • Physiology
  • Cell Biology

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