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Zinc Acts as a Potent Inhibitor of Aspirin Induced Gastric Acid Secretion in Rat Gastric Glands
AGA Abstracts
functionally active DRA without the PDZ interacting motif (DRA-ETKFminus) served as controls. The activity of DRA and DRA-ETKFminus at different PonA concentrations was measured using BCECF. Surface biotinylation experiments were performed to investigate DRA plasma membrane expression. The effect of SNX27 expression and KD on DRA protein turnover was determined after cycloheximide (CHX) induced inhibition of protein synthesis. Results: BCECF pHi measurements showed that the flux of DRA was slightly decreased after 5 µM PonA treatment (~ 8fold SNX27 overexpression) compared to non-induced cells (0.84 ± 0.05 mM/s vs. 1.00 ± 0.05, p<0.05, n≥13). Additionally, DRA activity was markedly reduced by more than 50% in SNX27 KD cells (n=18). In contrast, SNX27 overexpression as well as the KD had no effect on the activity of DRA-ETKFminus (1.34 ± 0.08 mM/s (PonA) vs. 1.33 ± 0.09 (control), n≥11). Relative surface expression of DRA (21.4 ± 3.5% (PonA) vs. 22.5 ± 6.6% (control), n=5) was higher than of DRA-ETKFminus (12.9 ± 4.8% (PonA) vs. 15.4 ± 5.4% (control), n=6) but not affected by SNX27 overexpression. The protein turnover of DRA was neither changed by SNX27 overexpression nor by KD. Summary and Conclusion: SNX27 KD markedly decreased the activity of DRA but not DRA-ETKFminus. Further, SNX27 overexpression also led to a slight decrease of DRA activity suggesting not only a role of SNX27 in DRA recycling but also another underlying mechanism. DRA was expressed to a greater extent in the plasma membrane compared to DRA-ETKFminus. This indicates that PDZ interaction plays a crucial role for DRA surface expression and subsequent activity. Unexpectedly, DRA protein turnover was not affected by SNX27 overexpression or KD. To further investigate the influence of SNX27 on the trafficking of DRA, DRA surface expression is studied under SNX27 KD conditions and 3D superresolution SIM is performed to determine the colocalisation of SNX27 and DRA in different endosomal compartments in Caco2 cells.
vitamin C recovery rates were not significantly different from those of Zoniporide alone, or Zoniporide-Vitamin C in combination. In a separate set of experiments, perfusing the crypts with solutions containing different doses of Amiloride resulted in slower recovery rates in comparison to control or vitamin C containing experiments. In a separate series we observed that there was an increase in the Na-dependent recovery in solutions containing both Vitamin C and Amiloride. Conclusion: Comparing the extrusion rate of Vitamin C to that of Zoniporide showed no significance different, demonstrating that the vitamin C effect is not modulating NHE1. In separate studies of NHE selective doses of Amiloride, the extrusion rate was maximally modulated at the highest dose of Vitamin C which suggests that this effect is on the NHE4 protein. This exciting observation suggests that the role of NHE4 may be critical for the anti-tumorigenic effects of Vitamin C on the colon.
Tu1596 THE GHRELIN SIGNAL ENHANCEMENT EFFECT OF RIKKUNSHITO IS MEDIATED VIA ATRACTYLODIN AND ITS METABOLITE, ATRACTYLODIN CARBOXYLIC ACID Miwa Nahata, Yasuharu Mizuhara, Chiharu Sadakane, Junko Watanabe, Naoki Fujitsuka, Tomohisa Hattori Background/Aim: Ghrelin is known to induce gastrointestinal (GI) motility. Patients with functional dyspepsia or cancer cachexia often exhibit increased plasma ghrelin concentrations, suggesting lowered ghrelin signaling. The Kampo medicine rikkunshito (RKT) is prescribed for patients with various upper GI syndromes and is traditionally administered before or between meals. In pharmacokinetic research, atractylodin (ATR) and ATR carboxylic acid, its main metabolite, are the major active ingredients detected in the plasma of RKT-administered healthy volunteers. RKT and ATR have been shown to enhance ghrelin signaling in ghrelin receptor (GHS-R)-expressing cells. The aim of this study was to clarify the relationship between the ghrelin signal enhancement activity of RKT and pharmacokinetic profiles of ATR and its metabolite under fasting and fed conditions in rats. Methods: RKT (1000 mg/ kg) and ATR (1 mg/kg) were orally administered to rats during fasting or 30 min after providing a nutrient meal, followed by ghrelin (3 nmol) injection after 30 min. Motility in the gastric antrum for a 30-min period was evaluated using a strain gauge force transducer. Plasma and brain concentrations of ATR and ATR carboxylic acid, its metabolite, in rats following oral administration of RKT (1000 mg/kg) under fasting and fed conditions were measured by LC-MS/MS or GC/MS, and their pharmacokinetics were assessed. Radioligand binding assay of ghrelin to GHS-R was performed to measure the effect of ATR carboxylic acid using GSH-R-expressing cells. Results: The gastric motility in fasted rats was immediately increased following intravenous injection of ghrelin. Administration of RKT or ATR at 30 min before ghrelin injection potentiated the ghrelin-induced gastric motility. On the other hand, when RKT was administered to rats after providing the nutrient meal (i.e., under the fed condition), the enhancement effect of RKT was 30% lower than that under the fasting condition. The pharmacokinetic study revealed that ATR was detected in the plasma and brain with a peak at 0.25 and 0.5 h, respectively, after the administration of RKT, and these concentrations were higher in fasted rats than in fed rats. ATR carboxylic acid was also detected in the plasma, and the concentration was significantly greater than that of ATR in fasted rats. An in vitro assay revealed ATR carboxylic acid enhanced the ghrelin-binding activity in GHS-R-expressing cells. Conclusion Administration of RKT and ATR potentiated ghrelin-induced gastric motility under the fasting condition. The ghrelin signal enhancement effect of RKT may be mediated by ATR carboxylic acid, an ATR metabolite, as well as ATR. Central and peripheral GHS-R activation could be a therapeutic target for gastric dysfunction in patients with a high concentration of peripheral ghrelin.
Tu1594 KSR1/2 REGULATES ERK ACTIVATION AND NEUROTENSIN SECRETION Stephanie A. Bryant, Jun Song, Courtney M. Townsend, Jing Li, B. Mark Evers Neurotensin (NT), a tridecapeptide released from specialized enteroendocrine cells (N cells) in the small intestine in response to fat ingestion, has been implicated in metabolic disorders such as hepatic steatosis and insulin resistance. Although the mechanisms regulating NT secretion are still incompletely understood, our previous findings implicate a role for ERK1/ 2 and phosphatidylinositol 3-kinase (PI3K)/Akt signaling in positive and negative regulation of NT secretion, respectively. Recent evidence indicates that kinase suppressor of Ras 1 and 2 (KSR1 and KSR2) act as a molecular scaffold of the Raf/MEK/ERK signaling pathway; the link between KSR1/2 and NT secretion has not been investigated. The purpose of this study was to determine whether KSR1 and/or KSR2 modulates fatty acid (FA)-stimulated NT secretion through activation of the Raf/MEK/ERK pathway. METHODS For this study, we used the human endocrine cell line, BON, which synthesizes and secretes NT in a manner equivalent to that of N cells in the small bowel. i) First, we determined whether inhibition of KSR1 and KSR2 decreased NT secretion in BON cells. Cells were transfected with KSR1 or KSR2 siRNA. Forty-eight h after transfection, cells were treated with 100µM DHA (a long-chain unsaturated FA) for 1 h. Media was collected and NT secretion measured using an NT enzyme immunoassay (EIA). ii) To delineate whether KSR1 and KSR2 signaling regulates NT gene expression, quantitative real-time PCR was performed on BON cells transfected with KSR1 or KSR2 siRNA. iii) To examine activity of ERK1/2 and NT protein expression in response to KSR1 and 2 inhibition, cells were lysed, protein extracted, and western blot analysis performed. RESULTS Both basal and DHA-stimulated NT secretion was decreased in BON cells transfected with either KSR1 or KSR2 siRNA. NT mRNA and protein levels were unaffected by either DHA treatment or KSR1 and 2 inhibition, suggesting that the regulation of NT secretion by KSR1 and KSR2 is not through regulation of NT mRNA or protein synthesis. Consistently, inhibition of KSR1 and 2 inhibited ERK1/2 phosphorylation, suggesting an upstream regulation of KSR1 and 2 on ERK1/2 activity. CONCLUSIONS KSR1/2 inhibition reduces ERK activity and NT secretion in BON cells. These findings suggest that KSR1 and KSR2 positively regulate NT secretion through activation of ERK1/ 2. Based on our previous studies, indicating that PI3K/Akt signaling negatively regulates NT granule trafficking, we speculate that KSR1/2 regulates ERK1/2 activity and thus NT secretion through cross-inhibition of PI3K/Akt signaling and the modulation of secretory processes such as vesicle formation, trafficking or exocytosis.
Tu1597 ZINC ACTS AS A POTENT INHIBITOR OF ASPIRIN INDUCED GASTRIC ACID SECRETION IN RAT GASTRIC GLANDS Florentina Ferstl, Alice M. Kitay, John P. Geibel Aspirin has been widely used as a therapeutic for many years to treat a wide variety of acute and chronic conditions. It is recommended at high dose for pain relief, inflammation and fever. At low doses, it is routinely administered chronically to prevent strokes, myocardial infarction, blood clot formation, and more recently as an anti-cancer prophylactic therapy. With all of these benefits the number of individuals taking aspirin continues to expand logarithmically. In the stomach aspirin has been shown to increase the risk of ulcer formation by reducing the mucosal barrier and acting directly to suppress the production of mucous. Our group has recently shown that low dose aspirin also has a direct effect on the parietal cells and can lead to the secretion of acid via the H+, K+- ATPase even in the absence of secretagogues. In this study, we examined two isomers of zinc sulfate (ZnSO4), mono- and heptahydrate, that we have shown act as potent inhibitors of secretagogue induced gastric acid secretion and their effects on aspirin induced acid secretion. In one series of experiments, hand dissected glands were loaded with the pH-sensitive dye BCECF and aspirin (10µM) was added to non secretagogue stimulated glands inducing acid secretion. In separate series zinc isomers were added to examine the effects on aspirin induced pH recovery. Recovery of pH was calculated as change in pH/time for each salt under each condition following aspirin exposure to induce acid secretion. Addition of either salt (hepta-hydrate, monohydrate) resulted in a dose dependent inhibition of aspirin induced acid secretion. We have now shown that not only aspirin can induce acid secretion in the absence of secretagogues when added to the basolateral perfusate but that pre-incubation, or simultaneous incubation with zinc sulfate (mono or heptahydrate) resulted in a dose dependent inhibition of aspirin induced acid secretion. These results further support our view that zinc salts are potent nutraceutical inhibitors of acid secretion both from aspirin and classical secretagogues.
Tu1595 ACUTE EXPOSURE TO VITAMIN C ACTIVATES NA+-H+ EXCHANGER 4(NHE4) IN COLONIC CRYPTS Mohammed Aldajani, Norah Alhazzaa, John P. Geibel Introduction: Vitamin C is an essential water soluble vitamin that has many pathophysiologic roles in humans from aiding in the prevention of scurvy, to the more recent role as a potent anti-tumorigenic agent. Previous studies have shown that high concentrations of vitamin C lead to a dramatic reduction in colon cancer. Previous studies from our laboratory have shown that acute exposure to vitamin C can lead to reductions in Na+-H Exchanger activity (NHE) that results in increased intracellular acidity and elevations in extracellular pH in the immediate environment around the crypt. The goal of the present study was to further investigate the effects of vitamin C on NHE activity and to identify which NHE exchangers are modulated by acute exposure to vitamin C. Methods: Rat colon was excised and placed in a digestive solution (HEPES/EDTA) to isolate single crypt. To measure intracellular pH we incubated the individual crypt with the pH reporter dye BCECF. Following dye loading the crypts were exposed to a solution containing or devoid of 10 mM vitamin C. To induce an intracellular acidification, we used our NH4Cl prepulse technique. Following exposure to NH4Cl we washed into a 0 Na buffer solution and then into a Na containing perfusate, and measured the Na-dependent recovery rate. To determine which NHE(s) is vitamin C targeting in the acute condition, we used Zoniporide to selectively inhibit NHE1, for NHE24 we used Amiloride at the selective doses that would inhibit each exchanger. Amiloride or Zoniporide was added to all solutions in the presence or absence of Vitamin C. Results: Na+-dependent recovery rates were compared among different sets of experiments that contain or are devoid of the above mentioned drugs. In comparison to control experiments, vitamin C decreased the Na+-dependent recovery rate following an acid load. However,
AGA Abstracts
S-912
functionally active DRA without the PDZ interacting motif (DRA-ETKFminus) served as controls. The activity of DRA and DRA-ETKFminus at different PonA concentrations was measured using BCECF. Surface biotinylation experiments were performed to investigate DRA plasma membrane expression. The effect of SNX27 expression and KD on DRA protein turnover was determined after cycloheximide (CHX) induced inhibition of protein synthesis. Results: BCECF pHi measurements showed that the flux of DRA was slightly decreased after 5 µM PonA treatment (~ 8fold SNX27 overexpression) compared to non-induced cells (0.84 ± 0.05 mM/s vs. 1.00 ± 0.05, p<0.05, n≥13). Additionally, DRA activity was markedly reduced by more than 50% in SNX27 KD cells (n=18). In contrast, SNX27 overexpression as well as the KD had no effect on the activity of DRA-ETKFminus (1.34 ± 0.08 mM/s (PonA) vs. 1.33 ± 0.09 (control), n≥11). Relative surface expression of DRA (21.4 ± 3.5% (PonA) vs. 22.5 ± 6.6% (control), n=5) was higher than of DRA-ETKFminus (12.9 ± 4.8% (PonA) vs. 15.4 ± 5.4% (control), n=6) but not affected by SNX27 overexpression. The protein turnover of DRA was neither changed by SNX27 overexpression nor by KD. Summary and Conclusion: SNX27 KD markedly decreased the activity of DRA but not DRA-ETKFminus. Further, SNX27 overexpression also led to a slight decrease of DRA activity suggesting not only a role of SNX27 in DRA recycling but also another underlying mechanism. DRA was expressed to a greater extent in the plasma membrane compared to DRA-ETKFminus. This indicates that PDZ interaction plays a crucial role for DRA surface expression and subsequent activity. Unexpectedly, DRA protein turnover was not affected by SNX27 overexpression or KD. To further investigate the influence of SNX27 on the trafficking of DRA, DRA surface expression is studied under SNX27 KD conditions and 3D superresolution SIM is performed to determine the colocalisation of SNX27 and DRA in different endosomal compartments in Caco2 cells.
vitamin C recovery rates were not significantly different from those of Zoniporide alone, or Zoniporide-Vitamin C in combination. In a separate set of experiments, perfusing the crypts with solutions containing different doses of Amiloride resulted in slower recovery rates in comparison to control or vitamin C containing experiments. In a separate series we observed that there was an increase in the Na-dependent recovery in solutions containing both Vitamin C and Amiloride. Conclusion: Comparing the extrusion rate of Vitamin C to that of Zoniporide showed no significance different, demonstrating that the vitamin C effect is not modulating NHE1. In separate studies of NHE selective doses of Amiloride, the extrusion rate was maximally modulated at the highest dose of Vitamin C which suggests that this effect is on the NHE4 protein. This exciting observation suggests that the role of NHE4 may be critical for the anti-tumorigenic effects of Vitamin C on the colon.
Tu1596 THE GHRELIN SIGNAL ENHANCEMENT EFFECT OF RIKKUNSHITO IS MEDIATED VIA ATRACTYLODIN AND ITS METABOLITE, ATRACTYLODIN CARBOXYLIC ACID Miwa Nahata, Yasuharu Mizuhara, Chiharu Sadakane, Junko Watanabe, Naoki Fujitsuka, Tomohisa Hattori Background/Aim: Ghrelin is known to induce gastrointestinal (GI) motility. Patients with functional dyspepsia or cancer cachexia often exhibit increased plasma ghrelin concentrations, suggesting lowered ghrelin signaling. The Kampo medicine rikkunshito (RKT) is prescribed for patients with various upper GI syndromes and is traditionally administered before or between meals. In pharmacokinetic research, atractylodin (ATR) and ATR carboxylic acid, its main metabolite, are the major active ingredients detected in the plasma of RKT-administered healthy volunteers. RKT and ATR have been shown to enhance ghrelin signaling in ghrelin receptor (GHS-R)-expressing cells. The aim of this study was to clarify the relationship between the ghrelin signal enhancement activity of RKT and pharmacokinetic profiles of ATR and its metabolite under fasting and fed conditions in rats. Methods: RKT (1000 mg/ kg) and ATR (1 mg/kg) were orally administered to rats during fasting or 30 min after providing a nutrient meal, followed by ghrelin (3 nmol) injection after 30 min. Motility in the gastric antrum for a 30-min period was evaluated using a strain gauge force transducer. Plasma and brain concentrations of ATR and ATR carboxylic acid, its metabolite, in rats following oral administration of RKT (1000 mg/kg) under fasting and fed conditions were measured by LC-MS/MS or GC/MS, and their pharmacokinetics were assessed. Radioligand binding assay of ghrelin to GHS-R was performed to measure the effect of ATR carboxylic acid using GSH-R-expressing cells. Results: The gastric motility in fasted rats was immediately increased following intravenous injection of ghrelin. Administration of RKT or ATR at 30 min before ghrelin injection potentiated the ghrelin-induced gastric motility. On the other hand, when RKT was administered to rats after providing the nutrient meal (i.e., under the fed condition), the enhancement effect of RKT was 30% lower than that under the fasting condition. The pharmacokinetic study revealed that ATR was detected in the plasma and brain with a peak at 0.25 and 0.5 h, respectively, after the administration of RKT, and these concentrations were higher in fasted rats than in fed rats. ATR carboxylic acid was also detected in the plasma, and the concentration was significantly greater than that of ATR in fasted rats. An in vitro assay revealed ATR carboxylic acid enhanced the ghrelin-binding activity in GHS-R-expressing cells. Conclusion Administration of RKT and ATR potentiated ghrelin-induced gastric motility under the fasting condition. The ghrelin signal enhancement effect of RKT may be mediated by ATR carboxylic acid, an ATR metabolite, as well as ATR. Central and peripheral GHS-R activation could be a therapeutic target for gastric dysfunction in patients with a high concentration of peripheral ghrelin.
Tu1594 KSR1/2 REGULATES ERK ACTIVATION AND NEUROTENSIN SECRETION Stephanie A. Bryant, Jun Song, Courtney M. Townsend, Jing Li, B. Mark Evers Neurotensin (NT), a tridecapeptide released from specialized enteroendocrine cells (N cells) in the small intestine in response to fat ingestion, has been implicated in metabolic disorders such as hepatic steatosis and insulin resistance. Although the mechanisms regulating NT secretion are still incompletely understood, our previous findings implicate a role for ERK1/ 2 and phosphatidylinositol 3-kinase (PI3K)/Akt signaling in positive and negative regulation of NT secretion, respectively. Recent evidence indicates that kinase suppressor of Ras 1 and 2 (KSR1 and KSR2) act as a molecular scaffold of the Raf/MEK/ERK signaling pathway; the link between KSR1/2 and NT secretion has not been investigated. The purpose of this study was to determine whether KSR1 and/or KSR2 modulates fatty acid (FA)-stimulated NT secretion through activation of the Raf/MEK/ERK pathway. METHODS For this study, we used the human endocrine cell line, BON, which synthesizes and secretes NT in a manner equivalent to that of N cells in the small bowel. i) First, we determined whether inhibition of KSR1 and KSR2 decreased NT secretion in BON cells. Cells were transfected with KSR1 or KSR2 siRNA. Forty-eight h after transfection, cells were treated with 100µM DHA (a long-chain unsaturated FA) for 1 h. Media was collected and NT secretion measured using an NT enzyme immunoassay (EIA). ii) To delineate whether KSR1 and KSR2 signaling regulates NT gene expression, quantitative real-time PCR was performed on BON cells transfected with KSR1 or KSR2 siRNA. iii) To examine activity of ERK1/2 and NT protein expression in response to KSR1 and 2 inhibition, cells were lysed, protein extracted, and western blot analysis performed. RESULTS Both basal and DHA-stimulated NT secretion was decreased in BON cells transfected with either KSR1 or KSR2 siRNA. NT mRNA and protein levels were unaffected by either DHA treatment or KSR1 and 2 inhibition, suggesting that the regulation of NT secretion by KSR1 and KSR2 is not through regulation of NT mRNA or protein synthesis. Consistently, inhibition of KSR1 and 2 inhibited ERK1/2 phosphorylation, suggesting an upstream regulation of KSR1 and 2 on ERK1/2 activity. CONCLUSIONS KSR1/2 inhibition reduces ERK activity and NT secretion in BON cells. These findings suggest that KSR1 and KSR2 positively regulate NT secretion through activation of ERK1/ 2. Based on our previous studies, indicating that PI3K/Akt signaling negatively regulates NT granule trafficking, we speculate that KSR1/2 regulates ERK1/2 activity and thus NT secretion through cross-inhibition of PI3K/Akt signaling and the modulation of secretory processes such as vesicle formation, trafficking or exocytosis.
Tu1597 ZINC ACTS AS A POTENT INHIBITOR OF ASPIRIN INDUCED GASTRIC ACID SECRETION IN RAT GASTRIC GLANDS Florentina Ferstl, Alice M. Kitay, John P. Geibel Aspirin has been widely used as a therapeutic for many years to treat a wide variety of acute and chronic conditions. It is recommended at high dose for pain relief, inflammation and fever. At low doses, it is routinely administered chronically to prevent strokes, myocardial infarction, blood clot formation, and more recently as an anti-cancer prophylactic therapy. With all of these benefits the number of individuals taking aspirin continues to expand logarithmically. In the stomach aspirin has been shown to increase the risk of ulcer formation by reducing the mucosal barrier and acting directly to suppress the production of mucous. Our group has recently shown that low dose aspirin also has a direct effect on the parietal cells and can lead to the secretion of acid via the H+, K+- ATPase even in the absence of secretagogues. In this study, we examined two isomers of zinc sulfate (ZnSO4), mono- and heptahydrate, that we have shown act as potent inhibitors of secretagogue induced gastric acid secretion and their effects on aspirin induced acid secretion. In one series of experiments, hand dissected glands were loaded with the pH-sensitive dye BCECF and aspirin (10µM) was added to non secretagogue stimulated glands inducing acid secretion. In separate series zinc isomers were added to examine the effects on aspirin induced pH recovery. Recovery of pH was calculated as change in pH/time for each salt under each condition following aspirin exposure to induce acid secretion. Addition of either salt (hepta-hydrate, monohydrate) resulted in a dose dependent inhibition of aspirin induced acid secretion. We have now shown that not only aspirin can induce acid secretion in the absence of secretagogues when added to the basolateral perfusate but that pre-incubation, or simultaneous incubation with zinc sulfate (mono or heptahydrate) resulted in a dose dependent inhibition of aspirin induced acid secretion. These results further support our view that zinc salts are potent nutraceutical inhibitors of acid secretion both from aspirin and classical secretagogues.
Tu1595 ACUTE EXPOSURE TO VITAMIN C ACTIVATES NA+-H+ EXCHANGER 4(NHE4) IN COLONIC CRYPTS Mohammed Aldajani, Norah Alhazzaa, John P. Geibel Introduction: Vitamin C is an essential water soluble vitamin that has many pathophysiologic roles in humans from aiding in the prevention of scurvy, to the more recent role as a potent anti-tumorigenic agent. Previous studies have shown that high concentrations of vitamin C lead to a dramatic reduction in colon cancer. Previous studies from our laboratory have shown that acute exposure to vitamin C can lead to reductions in Na+-H Exchanger activity (NHE) that results in increased intracellular acidity and elevations in extracellular pH in the immediate environment around the crypt. The goal of the present study was to further investigate the effects of vitamin C on NHE activity and to identify which NHE exchangers are modulated by acute exposure to vitamin C. Methods: Rat colon was excised and placed in a digestive solution (HEPES/EDTA) to isolate single crypt. To measure intracellular pH we incubated the individual crypt with the pH reporter dye BCECF. Following dye loading the crypts were exposed to a solution containing or devoid of 10 mM vitamin C. To induce an intracellular acidification, we used our NH4Cl prepulse technique. Following exposure to NH4Cl we washed into a 0 Na buffer solution and then into a Na containing perfusate, and measured the Na-dependent recovery rate. To determine which NHE(s) is vitamin C targeting in the acute condition, we used Zoniporide to selectively inhibit NHE1, for NHE24 we used Amiloride at the selective doses that would inhibit each exchanger. Amiloride or Zoniporide was added to all solutions in the presence or absence of Vitamin C. Results: Na+-dependent recovery rates were compared among different sets of experiments that contain or are devoid of the above mentioned drugs. In comparison to control experiments, vitamin C decreased the Na+-dependent recovery rate following an acid load. However,
AGA Abstracts
S-912