Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Free fatty acids can enter the enterocyte via the apical or basolateral plasma membrane. We have used the Caco-2 intestinal cell line to examine the polarity of free fatty acid uptake and metabolism in the enterocyte. Differentiated Caco-2 cells form polarized monolayers with tight junctions, and express the small intestine-specific enzymes sucrase and alkaline phosphatase. Cells were grown on permeable polycarbonate Transwell filters, thus allowing separate access to the apical and basolateral compartments. Total uptake of [3H]palmitate bound to bovine serum albumin (palmitate-BSA 4:1) was twofold higher (P less than 0.05 or less) at the apical surface than at the basolateral surface. The relative apical and basolateral membrane surface areas of the Caco-2 cells, as measured by partition of the fluorophore trimethylammonium-diphenylhexatriene TMA-DPH), was found to be 1:3. Thus, apical fatty acid uptake was sixfold higher than basolateral uptake per unit surface area. Analysis of metabolites after incubation with submicellar concentrations of [3H]palmitate showed that the triacylglycerol to phospholipid (TG:PL) ratio was higher for fatty acid added to the apical as compared to the basolateral compartment (20% at 60 min, P less than 0.025). Little fatty acid oxidation was observed. Preincubation with albumin-bound palmitate, alone or with monoolein, increased the incorporation of both apical and basolateral free fatty acids into TG. The results suggest that the net uptake of long-chain free fatty acids across the apical plasma membrane is greater than uptake across the basolateral membrane. In addition, a small increase in the TG:PL ratio for apically, compared to basolaterally, added free fatty acids suggests that polarity of metabolism occurs to a limited extent in Caco-2 enterocytes.
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PMID:Fatty acid uptake and metabolism in a human intestinal cell line (Caco-2): comparison of apical and basolateral incubation. 206 64

The effect of acute in vivo epidermal growth factor (EGF) exposure on intestinal absorptive surface area was examined in blind jejunal loops in New Zealand White rabbits (500-900 g). Brush-border surface area was assessed by electron microscopy at 30 and 120 min, and total surface area was assessed by the fluorophore 1-[4-(trimethylamino)phenyl)]-6-phenylhexatriene (TMA-DPH) at 10 and 60 min after EGF exposure. Mucosa obtained at 120 min was also used for morphometrics and analysis of membrane composition and fluidity. Brush-border surface area was significantly increased in EGF-treated tissue after 30 (42%) and 120 min (60%). Total absorptive surface area measured by TMA-DPH was increased more than twofold after 10 and 60 min EGF exposure. The increase in absorptive surface area was abolished by pretreatment with intravenous verapamil. Mucosal morphometrics and membrane sucrase activity, total phospholipids, cholesterol content, cholesterol-to-phospholipid ratio, phospholipid species (wt%), phospholipid fatty acid composition, and fluidity did not differ between control and EGF-treated tissue. These findings indicate that EGF can rapidly increase brush-border surface area by a mechanism that appears to be due to a redistribution of existing performed microvillus plasma membrane.
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PMID:Effect of epidermal growth factor on enterocyte brush-border surface area. 844 14