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Contribution of Mucosal Maltase‐Glucoamylase to Mouse Small Intestinal Starch α‐Glucogenesis and Total Glucose Metabolism
Author(s) -
Nichols Buford L,
QuezadaCalvillo Roberto,
Ao Zihua,
Hamaker Bruce R,
Marini Juan,
Jahoor Farook
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.686.2
Subject(s) - chemistry , dextrin , medicine , endocrinology , maltase , carbohydrate metabolism , metabolism , starch , in vivo , digestion (alchemy) , biochemistry , enzyme , biology , chromatography , microbiology and biotechnology
Digestion of starch requires four mucosal maltases; sucrase and isomaltase (Si) and maltase and glucoamylase (Mgam). We ablated Mgam to study its roles. The in vitro effect was a slowing of null mucosal activity to 10% of WT. Here we report in vivo effects of Mgam KO on mouse glucose metabolism. α‐Glucogenesis was assayed by digestion of IG 13 C‐starch to blood 13 C‐glucose. UL 13 C‐starch (Sigma: M+6) was predigested with amylase (Sigma) to 13 C‐limit dextrin (LD), which contained 3.48 ± 0.12 g/L glucose equivalents. 13 C‐LD was infused IG. D‐Glucose‐C‐d7 (Isotec: M+7) was infused IV (7.5 g/L) to measure total glucose flux. Mice were fasted overnight and tail vein and gastric cannulas inserted. Both IG snd IV were infused at 0.0001 L/h. 4 h blood was collected from submandibular sinus. Total glucose was measured by analyzer and glucose isotopomers as penta‐acetate derivatives by PCI‐GC/MS. Baseline bloods were from uninfused mice. The null has only 60% of WT α‐glucogenesis. Because of increased null gluconeogenesis, total glucose metabolism in Mgam null mice was identical to WT.