Na,K-ATPase in diabetic rat small intestine. Changes at protein and mRNA levels and role of glucagon.

Barada, Kassem; Okolo, Chidinma; Field, Michael; Cortas, Nadim

doi:10.1172/jci117287

Cited by 20 publications

(11 citation statements)

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“…As in any study measuring mRNA levels, the possibility that the effect is on mRNA stability and thus on mRNA half-life cannot be distinguished from an effect on gene expression. Differential regulation of isozyme gene expression has been demonstrated previously for isozymes of Na,K-ATPase in developing rat brain, heart, lung, and kidney (Orlowski and Lingrel 1988;Charlemagne et al 1994;Barada et al 1994;Herrera et al 1994). A study similar to ours but conducted with chronic alcohol exposure in mice also concluded that increased Na,K-ATPase activity was due to increased levels of mRNA (Chen et al 1997).…”

Section: Discussionsupporting

confidence: 80%

Altered Pattern of Na,K-ATPase Activity and mRNA During Chronic Alcohol Consumption by Juvenile and Adolescent Rats

2008

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The effect of chronic ethanol consumption on cerebral cortical activity of Na,K-ATPase was determined in Long-Evans (LE) rats fed an ethanol-containing diet beginning at different stages of development. Na,K-ATPase activity was operationally resolved into alpha1 and alpha2/3 isozyme activities. There was no significant difference in Na,K-ATPase activities before and after alcohol consumption in the preparations from adult rats. However, for rats beginning alcohol consumption as adolescents, the alpha2/3 activity was significantly elevated following chronic alcohol consumption. Both LE and Sprague-Dawley rats showed this same selective increase in cortical alpha2/3 activity when rats began alcohol consumption as juveniles. The shift in cortical alpha2/3 activity was not observed in cerebellum or subcortical forebrain and was reversible when rats were fed ethanol throughout the normal adolescent period and then withdrawn and tested 2 weeks later (during the adult period). Levels of isoform-specific mRNA were determined in preparations of cerebral cortices of rats showing elevated alpha2/3 isozyme activities. In these preparations, isoform specific alpha2 and alpha3 mRNA was significantly elevated. There was no effect of ethanol feeding on cortical alpha1 mRNA. These findings indicate that the longer term effects of ethanol on the developing brain include elevated Na,K-ATPase activity and a mechanism that is pre-translational and isoform specific.

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Section: Discussionsupporting

confidence: 80%

Altered Pattern of Na,K-ATPase Activity and mRNA During Chronic Alcohol Consumption by Juvenile and Adolescent Rats

2008

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“…The rat small intestine, has been shown to contain a distinct isoform of the hydrolytic peptide of (Na + , K + )‐ATPase ( Zemelman et al . 1992 , Barada et al . 1994 ) and recalculation of data on mucosal scrapes would indicate a high concentration of Na + , K + ‐ATPase in this monolayer epithelium ( Barada et al .…”

Section: Discussionmentioning

confidence: 99%

“…1992 , Barada et al . 1994 ) and recalculation of data on mucosal scrapes would indicate a high concentration of Na + , K + ‐ATPase in this monolayer epithelium ( Barada et al . 1994 ).…”

Section: Discussionmentioning

confidence: 99%

Isoform of Na⁺, K⁺‐ATPase from rumen epithelium identified and quantified by immunochemical methods

Hansen

1998

Acta Physiologica Scandinavica

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Using biopsies of rumen epithelium papillae a net influx of [86Rb+] was measured corresponding to a high concentration of Na+, K(+)-pumps found in [3H]ouabain-binding studies (Kristensen et al. 1995). In the present study the Na+, K(+)-ATPase in papillae homogenates is compared with purified (Na+, K+)-ATPase from different sources, immunochemically characterized with respect to the isoform of the hydrolytic alpha subunit and the concentration of pumps substantiated by a novel immunochemical method. Na+, K(+)-ATPase purified from bovine kidney was shown to contain one homogeneous high-affinity population of [3H]ouabain-binding sites (Kd 1.37 nM). The ouabain-binding capacity was 0.82 nmol (mg protein)-1. Site-directed polyclonal antibodies raised to isoform-specific sequences of the three known alpha-subunit isoforms and monoclonal alpha 1-specific antibodies were used for isoform characterization on western blots of peptides separated by SDS-polyacrylamide gel electrophoresis. All three isoforms were present in Na+, K(+)-ATPase prepared from bovine brain. The alpha isoform of bovine kidney Na+, K(+)-ATPase and of rumen epithelium homogenate appeared to be alpha 1 whereas alpha 2 and alpha 3 were undetectable. Using an alpha 1-specific antibody and 125I-labelled antimouse IgG the content of (Na+, K+)-ATPase in rumen epithelium was determined by comparison of the signal from known amount of bovine kidney Na+, K(+)-ATPase on western blots. By this method rumen epithelium was found to contain 2.6 nmol Na+, K(+)-ATPase (g wet wt)-1, i.e. a similarly high or even higher concentration than previously seen in ouabain-binding studies on biopsies.

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“…A possibility exists that decreased contractility to carbachol and galanin may represent a generalized dysfunction in the contractile apparatus of smooth muscle. Nonetheless, the increased contractile responses to acetylcholine and KCl observed for up to 12 weeks in the gastric fundus of STZ diabetic rats and the normal reactivity of the duodenal and gastric muscles to directly acting relaxants in diabetic rats both 3-4 weeks after injection of STZ and 6 months after the onset of diabetes in BB/W rats speak strongly against it [17,30,35,36]. Decreased extracellular Ca 2+ influx into smooth muscle cells may be a plausible explanation for the diminished E max to galanin.…”

Section: Discussionmentioning

confidence: 99%

Effects of Diabetes mellitus on the Contractile Activity of Carbachol and Galanin in Isolated Gastric Fundus Strips of Rats

et al. 1998

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The role of the cholinergic and peptidergic pathways in the impairment of gastric motility associated with diabetic gastroparesis was assessed at the postsynaptic level using isolated fundus smooth muscle strips. Maximal contractile responses to carbachol and galanin were significantly decreased in fundus strips isolated from rats rendered diabetic by a single intraperitoneal injection of streptozotocin (STZ, 70 mg/kg) 1, 4 and 8 weeks before experiments. We also observed notable decrements in the slopes and Hill’s coefficients without conspicuous changes in the EC₅₀ of the respective galanin concentration-response curves measured in strips obtained from STZ animals after 4 and 8 weeks. L-NAME reversed the above-mentioned alterations in an L-arginine-sensitive manner in STZ rats after 4 weeks but not in STZ rats after 8 weeks. The blood plasma nitrite/nitrate levels in STZ animals after 4 and 8 weeks were increased by 44.6 and 61.9%, respectively. Ca²⁺-independent nitric oxide synthase activity in gastric fundus strips and stomach corpus mucosa from STZ rats after 4 weeks was markedly enhanced by 37.4 and 31.9%, respectively, suggesting an enhanced nitric oxide production. In vivo insulin treatment prevented diabetes-induced alterations in smooth muscle contractility. We conclude that the smooth muscle dysfunction evoked by experimental diabetes causing diminished contractions of fundus strips to carbachol and galanin is at least partly due to the increased nitric oxide synthesis.

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Na,K-ATPase in diabetic rat small intestine. Changes at protein and mRNA levels and role of glucagon.

Abstract: Na,K-ATPase activity and isoform expression were measured in rat small intestinal mucosa taken from both normal and streptozocin-treated diabetic rats. Enzyme activity and abundance was 1.7-23-fold higher in rats diabetic for 2 wk than in controls. This was associated with 1.

Cited by 20 publications

References 54 publications

Altered Pattern of Na,K-ATPase Activity and mRNA During Chronic Alcohol Consumption by Juvenile and Adolescent Rats

Altered Pattern of Na,K-ATPase Activity and mRNA During Chronic Alcohol Consumption by Juvenile and Adolescent Rats

Isoform of Na⁺, K⁺‐ATPase from rumen epithelium identified and quantified by immunochemical methods

Effects of Diabetes mellitus on the Contractile Activity of Carbachol and Galanin in Isolated Gastric Fundus Strips of Rats

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Na,K-ATPase in diabetic rat small intestine. Changes at protein and mRNA levels and role of glucagon.

Abstract: Na,K-ATPase activity and isoform expression were measured in rat small intestinal mucosa taken from both normal and streptozocin-treated diabetic rats. Enzyme activity and abundance was 1.7-23-fold higher in rats diabetic for 2 wk than in controls. This was associated with 1.

Cited by 20 publications

References 54 publications

Altered Pattern of Na,K-ATPase Activity and mRNA During Chronic Alcohol Consumption by Juvenile and Adolescent Rats

Altered Pattern of Na,K-ATPase Activity and mRNA During Chronic Alcohol Consumption by Juvenile and Adolescent Rats

Isoform of Na+, K+‐ATPase from rumen epithelium identified and quantified by immunochemical methods

Effects of Diabetes mellitus on the Contractile Activity of Carbachol and Galanin in Isolated Gastric Fundus Strips of Rats

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Isoform of Na⁺, K⁺‐ATPase from rumen epithelium identified and quantified by immunochemical methods