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

2009 ◽  
Vol 297 (4) ◽  
pp. C979-C989 ◽  
Author(s):  
Haley B. Naik ◽  
Melissa Beshire ◽  
Breda M. Walsh ◽  
Jingjing Liu ◽  
David I. Soybel
Keyword(s):  
Parietal Cell ◽  
Endocrine Cells ◽  
Cell Uptake ◽  
Exocrine Glands ◽  
Gastric Glands ◽  
Gastric Parietal Cell ◽  
Functional Roles ◽  
Isolated Gastric Glands ◽  
Acid Secreting ◽  
Insight Into

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 Zn2+ 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 Zn2+ 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.

Functionally distinct pools of actin in secretory cells

2001 ◽  
Vol 281 (2) ◽  
pp. C407-C417 ◽  
Author(s):  
David A. Ammar ◽  
Phuong N. B. Nguyen ◽  
John G. Forte
Keyword(s):  
Parietal Cell ◽  
Cultured Cells ◽  
Parietal Cells ◽  
Secretory Cells ◽  
Resting Cells ◽  
Gastric Glands ◽  
Gastric Parietal Cell ◽  
Actin Organization ◽  
Isolated Gastric Glands ◽  
High Concentrations

Acid secretion by the gastric parietal cell is controlled through movement of vesicles containing the proton pump, the H+-K+-ATPase (HK). We have used latrunculin B (Lat B), which binds to monomeric actin, to investigate actin turnover in the stimulated parietal cell. In isolated gastric glands, relatively high concentrations of Lat B were required to inhibit acid accumulation (ED50∼70 μM). Cultured parietal cells stimulated in the presence of low Lat B (0.1–1 μM) have reduced lamellipodia formation and some aberrant punctate phalloidin-stained structures, but translocation of HK and vacuolar swelling appeared unaffected. High Lat B (10–50 μM) resulted in gross changes in actin organization (punctate phalloidin-stained structures throughout the cell and nucleus) and reduced translocation of HK and vacuolar swelling. Resting parietal cells treated with high Lat B showed minor effects on morphology and F-actin staining. If resting cells treated with high Lat B were washed immediately before stimulation, they exhibited a normal stimulated morphology. These data suggest distinct pools of parietal cell actin: a pool highly susceptible to Lat B primarily involved in motile function of cultured cells; and a Lat B-resistant pool, most likely microvillar filaments, that is essential for secretion. Furthermore, the stimulation process appears to accentuate the effects of Lat B, most likely through Lat B binding to monomer actin liberated by the turnover of the motile actin filament pool.

scholarly journals Localization of ClC-2 Cl− channels in rabbit gastric mucosa

2001 ◽  
Vol 280 (6) ◽  
pp. C1599-C1606 ◽  
Author(s):  
Ann M. Sherry ◽  
Danuta H. Malinowska ◽  
Randal E. Morris ◽  
Georgianne M. Ciraolo ◽  
John Cuppoletti
Keyword(s):  
Gastric Mucosa ◽  
Parietal Cell ◽  
Functional Characterization ◽  
Parietal Cells ◽  
Immunogold Electron Microscopy ◽  
Gastric Glands ◽  
Canalicular Membrane ◽  
Isolated Gastric Glands ◽  
Hcl Secretion

HCl secretion across the parietal cell apical secretory membrane involves the H+-K+-ATPase, the ClC-2 Cl− channel, and a K+ channel. In the present study, the cellular and subcellular distribution of ClC-2 mRNA and protein was determined in the rabbit gastric mucosa and in isolated gastric glands. ClC-2 mRNA was localized to parietal cells by in situ hybridization and by direct in situ RT-PCR. By immunoperoxidase microscopy, ClC-2 protein was concentrated in parietal cells. Immunofluorescent confocal microscopy suggested that the ClC-2 was localized to the secretory canalicular membrane of stimulated parietal cells and to intracellular structures of resting parietal cells. Immunogold electron microscopy confirmed that ClC-2 is in the secretory canalicular membrane of stimulated cells and in tubulovesicles of resting parietal cells. These findings, together with previous functional characterization of the native and recombinant channel, strongly indicate that ClC-2 is the Cl− channel, which together with the H+-K+-ATPase and a K+ channel, results in HCl secretion across the parietal cell secretory membrane.

Inhibitory action of somatostatin on isolated gastric glands and parietal cells

1983 ◽  
Vol 245 (2) ◽  
pp. G221-G229 ◽  
Author(s):  
C. S. Chew
Keyword(s):  
Parietal Cell ◽  
Inhibitory Action ◽  
Parietal Cells ◽  
Acid Formation ◽  
Gastric Glands ◽  
Isolated Gastric Glands ◽  
Cell Acid ◽  
Kinetics Of ◽  
Apparent Ic50

The action of somatostatin in vitro was characterized using glands and parietal cells isolated from rabbit gastric mucosa. In the presence of the reducing agent dithiothreitol, somatostatin was found to inhibit gastrin- and histamine-stimulated acid formation in glands as measured by [14C]aminopyrine (AP) accumulation and oxygen consumption, both measurements that appear to be reliable indexes of parietal cell acid formation. In glands the inhibition of the secretory response to gastrin was more potent (60-80%) than that to histamine (15-25%). The kinetics of somatostatin inhibition of responses to both agents were noncompetitive. The apparent IC50 for the partial somatostatin inhibition of histamine-stimulated AP accumulation was similar to that for gastrin (approx 3 X 10(-9) M) when maximum concentrations of histamine (10(-4) M) or gastrin (10(-7) M) were used. The inhibitory action of somatostatin appeared to be specific, inasmuch as this peptide had no significant effect on basal secretion or secretion stimulated by carbachol, dibutyryl cAMP, cholera toxin, or elevated extracellular K+. In purified parietal cell preparations, somatostatin inhibited histamine- but not gastrin-stimulated AP accumulation. Moreover, the inhibition of histamine-stimulated AP accumulation in parietal cells was more pronounced than in glands. These results suggest that somatostatin acts directly on parietal cells to inhibit histamine activation of H+ secretion. Somatostatin also acts indirectly to inhibit gastrin, perhaps by blocking the release of histamine from paracrine- or endocrinelike cells present in the glands.

scholarly journals Targeted disruption of the Lasp-1 gene is linked to increases in histamine-stimulated gastric HCl secretion

2008 ◽  
Vol 295 (1) ◽  
pp. G37-G44 ◽  
Author(s):  
Catherine S. Chew ◽  
Xunsheng Chen ◽  
Roni J. Bollag ◽  
Carlos Isales ◽  
Ke Hong Ding ◽  
...  
Keyword(s):  
Parietal Cell ◽  
Secretory Response ◽  
Actin Binding ◽  
Weak Base ◽  
Targeted Disruption ◽  
Gastric Glands ◽  
Isolated Gastric Glands ◽  
Body Weights ◽  
Hcl Secretion

Lasp-1 (LIM and SH3 domain protein 1) is a multidomain actin-binding protein that is differentially expressed within epithelial tissues and brain. In the gastric mucosa, Lasp-1 is highly expressed in the HCl-secreting parietal cell, where it is prominently localized within the F-actin-rich subcellular regions. Histamine-induced elevation of parietal cell [cAMP]i increases Lasp-1 phosphorylation, which is correlated with activation of HCl secretion. To determine whether Lasp-1 is involved in the regulation of HCl secretion in vivo, we generated a murine model with a targeted disruption of the Lasp-1 gene. Lasp-1-null mice had slightly lower body weights but developed normally and had no overt phenotypic abnormalities. Basal HCl secretion was unaffected by loss of Lasp-1, but histamine stimulation induced a more robust acid secretory response in Lasp-1-null mice compared with wild-type littermates. A similar effect of histamine was observed in isolated gastric glands on the basis of measurements of accumulation of the weak base [14C]aminopyrine. In addition, inhibition of the acid secretory response to histamine by H2 receptor blockade with ranitidine proceeded more slowly in glands from Lasp-1-null mice. These findings support the conclusion that Lasp-1 is involved in the regulation of parietal HCl secretion. We speculate that cAMP-dependent phosphorylation of Lasp-1 alters interactions with F-actin and/or endocytic proteins that interact with Lasp-1, thereby regulating the trafficking/activation of the H+, K+-ATPase (proton pump).

Cl- requirement of acid secretion in isolated gastric glands

1983 ◽  
Vol 245 (4) ◽  
pp. G573-G581 ◽  
Author(s):  
D. H. Malinowska ◽  
J. Cuppoletti ◽  
G. Sachs
Keyword(s):  
Steady State ◽  
Acid Secretion ◽  
Parietal Cell ◽  
Acid Formation ◽  
Dibutyryl Camp ◽  
Steady State Distribution ◽  
State Distribution ◽  
Gastric Glands ◽  
Lateral Membrane ◽  
Isolated Gastric Glands

The dependence of acid formation, as measured by aminopyrine (AP) accumulation, on medium and intracellular Cl- was investigated in resting (10(-4) M cimetidine) and stimulated (10(-3) M dibutyryl cAMP) gastric glands isolated from the rabbit stomach. Intracellular Cl- concentrations (Cli-) were measured by the steady-state distribution of 36Cl-. In Cl- -free conditions AP accumulation was absent. Medium Cl- induced AP accumulation (AP ratio = 125) in stimulated glands with a K0.5 of 10.4 +/- 1.1 mM, equivalent to 18.0 +/- 1.2 mM Cli-, and had a small effect on resting glands (AP ratio = 6). With normal Nai+ and Ki+ maintained, similar results were obtained in stimulated glands treated with 10(-5) M amphotericin (ampho) and 10(-4) M ouabain (ouab), where the basal-lateral membrane was confirmed to be short-circuited with respect to Cl- pathways, i.e., medium Cl- and Cli- were equal. The K0.5 for Cl-i was 17.5 +/- 2.5 mM. In resting glands treated with ampho and ouab, AP accumulation increased linearly (no saturation was observed) with increasing Cl- (AP ratio = 35). These results suggest that stimulation activates a Cl- component in the secretory membrane and not in the basal-lateral membrane of the parietal cell. The K+ requirement of AP accumulation at a physiological Cl-i of 60 mM was also investigated in ampho- and ouab-treated glands. On stimulation the K0.5 for Ki+ decreased from 19.5 to 12 mM, coupled with a large increase in AP accumulation, indicating that stimulation also activates a K+ component in the secretory membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Modulatory role of phosphoinositide 3-kinase in gastric acid secretion

2007 ◽  
Vol 293 (3) ◽  
pp. G532-G543 ◽  
Author(s):  
S. E. Mettler ◽  
S. Ghayouri ◽  
G. P. Christensen ◽  
J. G. Forte
Keyword(s):  
Acid Secretion ◽  
Parietal Cell ◽  
Phosphodiesterase Inhibitors ◽  
Dominant Negative ◽  
Gastric Glands ◽  
Gastric Parietal Cell ◽  
Pi3k Inhibitor Ly294002 ◽  
Akt Phosphorylation ◽  
Phosphoinositide 3 Kinase

The gastric parietal cell is responsible for the secretion of HCl into the lumen of the stomach mainly due to stimulation by histamine via the cAMP pathway. However, the participation of several other receptors and pathways have been discovered to influence both stimulation and inhibition of acid secretion (e.g., cholinergic). Here we examine the role of phosphoinositide 3-kinase (PI3K) in the modulation of acid secretion. Treatment of isolated gastric glands and parietal cells with the PI3K inhibitor, LY294002 (LY), potentiated acid secretion in response to histamine to nearly the maximal secretion obtained with histamine plus phosphodiesterase inhibitors. As cAMP levels were elevated in response to histamine plus LY, but other means of elevating cAMP (e.g., forskolin, dbcAMP) were not influenced by LY, we posited that the effect might require activation of G-protein-coupled histamine H2 receptors, possibly through the protein kinase B pathway (also known as Akt). Study of downstream effectors of PI3K showed that histaminergic stimulation increased Akt phosphorylation, which in turn was blocked by inhibition of PI3K. Expression studies showed that high expression of active Akt decreased acid secretion, whereas dominant-negative Akt increased acid secretion. Taken together, these data suggest stimulation with histamine increases the activity of PI3K leading to increased activity of Akt and decreased levels of cAMP in the parietal cell.

Prostaglandin interaction with histamine release and parietal cell activity in isolated gastric glands

1986 ◽  
Vol 250 (5) ◽  
pp. G607-G616 ◽  
Author(s):  
O. Nylander ◽  
T. Berglindh ◽  
K. J. Obrink
Keyword(s):  
Oxygen Consumption ◽  
Parietal Cell ◽  
Cell Activity ◽  
Dependent Manner ◽  
Gastric Glands ◽  
Isolated Gastric Glands ◽  
Dose Dependent Fashion ◽  
Pg E2 ◽  
Opposing Effects ◽  
Dose Dependent

The effects of different prostanoids on parietal cell activity and glandular histamine (Hi) release were examined in isolated rabbit gastric glands. [14C]aminopyrine accumulation and glandular oxygen consumption were used as indices of parietal cell activity, and Hi was determined fluorophotometrically in the supernatant of the glandular suspensions. Both prostaglandins (PG) E2 and E1 dose dependently (10(-8) and 10(-6) M) increased the release of endogenous Hi. Carbacyclin was less effective and PGF2 alpha was almost without effect. Hi release induced by acetylcholine (Ach) and pentagastrin (Pg) was markedly potentiated in the presence of PGE2 (10(-8) to 10(-5) M). The Ach-induced sti ulation of Hi release was also potentiated by arachidonic acid (10(-5) M), an effect that was inhibitable by the cyclooxygenase inhibitor meclofenamate (3 X 10(-5) M). Somatostatin partially inhibited the response to Pg (3 X 10(-9) M) in combination with PGE2 (10(-5) M). Atropine (10(-5) M) strongly reduced the response elicited by Ach (3 X 10(-6) M) combined with PGE2 (10(-6) M). All prostanoids inhibited Hi (10(-4) M)-induced parietal cell activity in a dose-dependent manner (60-70%) but displayed different potency. The stimulatory response to Ach (3 X 10(-6) M) or Pg (3 X 10(-9) M) in combination with isobutylmethylxanthine (IBMX, 10(-5) M) was inhibited by PGE2 in a dose-dependent fashion. PGE2 (10(-6) M) was considerably more effective than cimetidine (10(-5) M) in inhibiting IBMX (10(-4) M)-stimulated oxygen consumption, and the remaining IBMX-PGE2 response (approximately 40%) was dose dependently (10(-8) to 10(-5) M) inhibited by cimetidine. Addition of Hi (10(-7) to 4 X 10(-7) M) or Pg (3 X 10(-10) to 3 X 10(-9) M) counteracted the PGE2 inhibition of the IBMX response. In addition, IBMX (10(-4) M) combined with PGE2 (10(-6) M) gave rise to a threefold increase in Hi release. These results suggest that prostaglandins have two opposing effects, i.e., liberation of endogenous Hi and inhibition of the action of Hi on the parietal cell.

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