Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.20 (alpha-glucosidase)
 4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of deoxycholate, taurocholate and cholate on transport and mucosal ATPase activity have been investigated in the rat jejunum in vivo using closed-loop and perfusion techniques. In the closed-loops, 5 mM deoxycholate selectively inactivated (Na+ + K+)-ATPase, and net secretion of Na+ induced by 2.5 mM deoxycholate was due to reduced lumen to plasma flux of the ion; deoxycholate (2.5 mM) produced marked inhibition of 3-0-methylglucose transport. Luminal disappearance rates of deoxycholate (60.5 plus or minus 2.9% per g wet st of gut) greatly exceeded those of taurocholate (4.3 plus or minus 1.0). In the perfusion studies 1 mM deoxycholate induced net secretion of water, Na+ and C1-, and inhibited active glucose transport; concomitantly "total" ATPase, (Na+ + K+)-ATPase, and Mg-2+-ATPase were inhibited. At higher concentrations (5 mM) deoxycholate stimulated Mg-2+-ATPase activity. Taurocholate and cholate at 1mM had no effect on transport of (Na+ + K+)-ATPase. Mucosal lactase, sucrase and maltase activities were not affected by 1 mM deoxycholate, taurocholate or cholate. These results suggest that deoxycholate inhibits sodium-coupled glucose transport by inhibition of (Na+ + K+)-ATPase at the lateral and basal membranes of the epithelial cell, rather than from an effect at the brush-border membrane level.
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PMID:A comparative study on the effects of different bile salts on mucosal ATPase and transport in the rat jejunum in vivo. 12 87

Mucosal response of alkaline phosphatase, ATPase and disaccharidase (lactase, maltase and trehalase) activities to sex hormones were studied by comparing male and female rats and castrated males and by injecting testosterone into castrated males. Alkaline phosphatase showed a very steep gradient in the small intestine from the oral to the aboral end, whereas ATPase activity in the ileum was still about 50% of that in the duodenum. Both enzymes showed only minor sex variations and weal response to castration. Lactase and maltase had peak activities in the jejunum, but trehalase activity was nearly equally high in the duodenal mucosa as in the jejunum. Jejunal lactase activity was about 50% lower in female than in male rats and castration decreased activity in males to the same low level as found in females. The administration of testosterone to castrated male rats did not enhance activity. Maltase activity showed similar sex variation, although castration was not able to decrease activity during the test period. Trehalase activity was lower in female than in male rats. The administration of testosterone enhance activity in castrated males.
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PMID:Sex variation in the activities of mucosal hydrolytic enzymes in the small intestine of the rat. 12 35

Mitochondrial and microsomal fractions were isolated from guinea pig myocardium by differential pelleting. The mitochondrial fraction was subjected to analytical subfractionation by sucrose density gradient centrifugation and the gradient fractions assayed for marker enzymes for the various mitochondrial compartments, viz outer membrane (monoamine oxidase), intermembranous space (adenylate kinase), inner membrane (Mg2+-dependent ATPase and cytochrome c oxidase) and mitochondrial matrix (malate dehydrogenase), and for creatine kinase. Both creatine kinase and adenylate kinase were released by suspending the mitochondria in 50 mmol . litre-1 sodium phosphate buffer. Sonication or disruption with the detergent, digitonin released the adenylate kinase but the creatine kinase remained associated with the inner membranes. Subsequent salt treatment desorbed the creatine kinase from these membranes. It is concluded that creatine kinase is located to the outer aspect of the inner mitochondrial membrane. Analytical subfractionation of the microsomal fraction clearly resolved markers for the sarcolemma (5'-nucleotidase), outer mitochondrial membrane (monoamine oxidase) and endoplasmic reticulum (neutral alpha-glucosidase and RNA). Creatine kinase was localised in the endoplasmic reticulum particularly the smooth membranes.
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PMID:Sub-mitochondrial and sub-microsomal distribution of creatine kinase in guinea pig myocardium. 51 58

Renal epithelial function, proton flux and sodium stimulated proton flux, was observed in vesicles isolated from the brush border of the proximal tubule of Sockeye Salmon (Oncorhynchus nerka) during migration. Brush border membrane vesicles (BBMV) were isolated from the body kidney of Sockeye Salmon using aggregation/differential centrifugation techniques. Vesicle purity was tested using a series of epithelial and basal lateral markers including alkaline phosphatase, maltase, gamma-glutamyl transferase (GGTP), Mg(2+)-activated ATP-ase, Na(+)+K(+)-activated ATPase, and 5'-nucleotidase and the lysosomal marker acid phosphatase. An enrichment/depletion factor for each marker was determined by comparison of purified BBMV with kidney homogenate. Vesicles exhibit an enrichment factor for alkaline phosphatase, GGTP, maltase, Mg(2+)-activated ATP-ase, Na(+)+K(+)-activated ATPase, and 5'-nucleotidase. A depletion factor was observed for acid phosphatase. Vesicle integrity was tested by measuring the time course of proton flux in the presence of a pH gradient. Amiloride sensitive sodium stimulated proton flux was observed in these vesicles. The presence of sodium caused a saturable increase in the rate of proton flux, indicating the activity of a sodium/proton antiport protein in BBMV.
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PMID:Proton transport and Na+/H+ exchange in vesicles isolated from sockeye salmon (Oncorhynchus nerka) kidneys during migration from salt to fresh water. 132 4

Oral administration of the antiulcerogenic drug, cimetidine, was studied on kidney-bound hydrolytic enzymes at three different dose levels (30 mg, 100 mg, and 2000 mg/kg body weight) and for single administration for 2 and 24 h, and daily administration for 15 days in mice. It significantly inhibited Na+, K(+)-ATPase, Mg(2+)-ATPase, and Ca2+, Mg(2+)-ATPase in the isolated basolateral membrane (BLM). Brush-border-membrane-(BBM)-associated enzymes, sucrase, lactase, maltase, leucine aminopeptidase, and alkaline phosphatase also showed a marked reduction. Substrate saturation kinetics revealed the nature of inhibition was of mixed type in the case of sucrase, lactase, maltase, and alkaline phosphatase (Km was increased, while Vmax decreased), whereas it was of non-competitive type for leucine aminopeptidase (Km was unchanged, while Vmax decreased). In vitro addition of cimetidine (5-20 mM) to the BBM also inhibited the enzyme activity. Dixon plot produced the inhibition constant (Ki) for cimetidine in the case of maltase, alkaline phosphatase, and leucine aminopeptidase in the order of 14.83, 32.83 and 11.5 mM, respectively. Analysis of lipids revealed a significant reduction in BBM-associated phospholipid and phospholipid/cholesterol molar ratio, while the neutral lipid fraction, i.e., cholesterol and triglycerides were not altered. Free fatty acid exhibited an increase after drug treatment, which was significant at higher dose after 24 h of single and 15 days of daily treatment. BLM-associated lipids did not exhibit any significant change. Cimetidine-induced depression in renal BLM- and BBM-associated disaccharidases and ATPases, at least at the higher dose level, may have serious consequences in the absorption of end-product nutrients.
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PMID:Depression of membrane-bound hydrolases by cimetidine in mouse renal basolateral and brush border. 183 34

A method is described for simultaneous preparation of brush-border and basolateral sea bass enterocyte membranes using simple differential centrifugation and discontinuous sucrose gradient density centrifugation techniques. Basolateral membranes were purified with a Na+/K(+)-ATPase yield of about 11% of the original activity, with an enrichment factor of 12. The yield of maltase-glucoamylase, a specific marker of brush-border membranes, was also about 11% of the original activity, with 15-fold enrichment. The characteristics of these membrane preparations were determined. Electron microscopy analysis showed that these two membrane preparations were uniform in size and vesicular in nature. Orientation studies revealed that the luminal membrane vesicles were right-side out and 43% of the antiluminal membrane vesicles were sealed inside out. Investigation of D-glucose and L-leucine uptake showed that these two plasma membrane preparations retained their transport properties.
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PMID:Simultaneous preparation of basolateral and brush-border membrane vesicles from sea bass intestinal epithelium. 215 52

The antiulcerogenic drug ranitidine, given orally to mice, brought about reductions of kidney-bound hydrolytic enzymes at three different dose levels, viz. 10 mg, 100 mg, and 1000 mg/kg body weight, and for three different time points (single administration for 2 h and 24 h, and daily administration for 15 days). The activities of Na+, K(+)-ATPase, Ca2(+)-ATPase, and Mg2(+)-ATPase (marker enzymes of basolateral membranes) were reduced, and these reductions were significant at higher doses and after a 24-h single treatment or 15 days' daily treatment. Maltase, alkaline phosphatase, and leucine aminopeptidase (marker enzymes of brush border membrane [BBM]) activities were significantly inhibited after ranitidine treatment. Kinetic analysis of BBM-associated enzymes indicated that ranitidine decreased the maximum of apparent initial enzyme velocity (Vmax) of maltase, alkaline phosphatase, and leucine aminopeptidase. The substrate affinity constant (Km) was decreased in the case of alkaline phosphatase and maltase, while it was not altered in the case of leucine aminopeptidase. In vitro addition of ranitidine to renal BBM also produced significant inhibition of these enzymes, the inhibition constants (Ki) for maltase, alkaline phosphatase, and leucine aminopeptidase being 7.5, 15.5, and 3.5 mM, respectively. Membrane-bound lipid estimation showed a significant increase in phospholipids, triglycerides, and free fatty acids. Cholesterol, however, was decreased in both renal basolateral and brush border membranes.
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PMID:Effect of histamine H2-receptor antagonist, ranitidine on renal brush border and basolateral membranes. 217 15

Distal urinary acidification is thought to be mediated by a proton ATPase (H+-ATPase). We isolated a plasma membrane fraction from human kidney cortex and medulla which contained H+-ATPase activity. In both the cortex and medulla the plasma membrane fraction was enriched in alkaline phosphatase, maltase, Na+,K+-ATPase and devoid of mitochondrial and lysosomal contamination. In the presence of oligomycin (to inhibit mitochondrial ATPase) in the presence of ouabain (to inhibit Na+,K+-ATPase) and in the absence of Ca (to inhibit Ca2+-ATPase) this plasma membrane fraction showed ATPase activity which was sensitive to dicyclohexylcarbodiimide and N-ethylmaleimide. This ATPase activity was also inhibited by vanadate, 4,4'-diisothiocyano-2,2'-disulfonic stilbene and ZnSO4. In the presence of ATP, but not GTP or UTP, the plasma membrane fraction of both cortex and medulla was capable of quenching of acridine orange fluorescence, which could be dissipated by nigericin indicating acidification of the interior of the vesicles. The acidification was not affected by presence of oligomycin or ouabain indicating that it was not due to mitochondrial ATPase or Na+,K+-ATPase, respectively. Dicyclohexylcarbodiimide and N-ethylmaleimide completely abolished the acidification by this plasma membrane fraction. In the presence of valinomycin and an outward-directed K gradient, there was increased quenching of acridine orange, indicating that the H+-ATPase is electrogenic. Acidification was not altered by replacement of Na by K, but was critically dependent on the presence of chloride. In summary, the plasma membrane fraction of the human kidney cortex and medulla contains a H+-ATPase, which is similar to the H+-ATPase described in other species, and we postulate that this H+-ATPase may be involved in urinary acidification.
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PMID:Plasma membrane proton ATPase from human kidney. 287 34

A model of nonischemic hypoxia of the jejunum was designed in dogs, by shunting of blood from the inferior vena cava directly into the regional mesenteric arterial supply, thereby lowering the PaO2 of the blood that reached the jejunal wall from 98.6 +/- 3 to 62 +/- 5 mm Hg. Absorption rates of sodium, glucose, fructose, glycine, and the dibasic aminoacid lysine were studied by in situ luminal perfusion of a 30-cm proximal jejunal segment with a bicarbonate buffer solution containing phenol red as a nonabsorbable marker for determination of water fluxes. During periods of control, hypoxia, and after discontinuation of the venoarterial admixture (recovery), effluent perfusate was collected and mucosal biopsies were obtained for assay of lactase, maltase and sucrase activity, mucosal ATPase activity and ATP content, and for light- and electron microscopic examination. Mesenteric supply with hypoxic blood was associated with a significant inhibition of Na+,K+-ATPase activity (p less than 0.001) and a rise in mucosal ATP content (p less than 0.05). There was a significant reduction in the absorption rates of sodium (p less than 0.001), glucose, and glycine (p less than 0.01), but no change in the transport of fructose and of lysine. Brush border enzymes were unaltered. The histological appearance of the mucosa remained normal throughout the experiment, but on electron microscopy a distinct swelling of the enterocyte mitochondria was noted during the hypoxia period.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of nonischemic hypoxia on jejunal mucosal structure and function: study of an experimental model in dogs. 294 46

Effects of non lethal concentrations of hexavalent chromium on intestinal enzymology of Salmo gairdneri and Dicentrarchus labrax (Pisces). The effects of an exposure to potassium dichromate on intestinal enzyme activities (Alkaline phosphatase, maltase, leucine amino peptidase and ATPases) have been studied on a fresh water fish (Salmo gairdneri) and a salt water fish (Dicentrarchus labrax). Fish were exposed at seasonal temperatures (13 or 21 degrees C) to toxic concentrations equal to 1/10 of the 24 h-LC 50 (i.e. 18 mg/l Cr for trout and 5 mg/l Cr for bass) during respectively 13 and 21 days. Intoxicated trout stopped feeding and showed a decrease in their intestinal weight at the end of the experiments. A decrease of brush border membrane activities (Alkaline phosphatase, maltase and leucine amino peptidase) were also observed. These alterations have been interpreted as the consequence of the chromium induces fasting. Intoxicated bass showed no alterations of their feeding habits. Two specific effects of chromium on enzyme activities have been found: a severe decrease of the alkaline phosphatase activity and an increase of the Na/K ATPase activity. These enzyme activities could be useful indicators of chromium intoxication in marine fish.
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PMID:[Effects of hexavalent chromium at non-lethal concentrations on the enzymology of the intestine of Salmo gairdneri and Dicentrarchus labrax (Pisces)]. 297 85


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