Biomaterial Database

Glucose-6-phosphatase activity in islets from ob/ob and lean mice and the effect of dexamethasone. 1995

A Khan, and C Hong-Lie, and B R Landau

Department of Molecular Medicine, Karolinska Hospital, Stockholm, Sweden.

In previous studies we demonstrated a much greater rate of glucose cycling (glucose-->glucose-6-P-->glucose) in islets from ob/ob mice than from lean litter mates. Cycling was further augmented by dexamethasone treatment. To determine whether these findings could be accounted for by increased islet glucose-6-phosphatase activity, we have now measured that enzyme's activity in permeabilized and sonicated islets and in islet microsomes. Activity in permeabilized islets from ob/ob mice was 19 times more than from lean litter mates (17.7 +/- 2.9 vs. 0.9 +/- 0.2 pmol/islet/min). Activity was 6 times higher when calculated per microgram of protein or microgram of DNA. Treatment of ob/ob mice with dexamethasone (25 micrograms/daily for 3 days) increased activity 2- to 3-fold. Activities were about twice as much in sonicated as permeabilized islets. There was no difference between glucose-6-phosphatase activity in microsomes prepared from islets of ob/ob and from lean mice, and the activity was relatively low. Thus, permeabilized islets can be used to determine glucose-6-phosphatase activity and study its regulation. The higher glucose cycling in islets of ob/ob mice and its stimulation by dexamethasone can be attributed to increased glucose-6-phosphatase activity.

UI	MeSH Term	Description	Entries
D007515	Islets of Langerhans	Irregular microscopic structures consisting of cords of endocrine cells that are scattered throughout the PANCREAS among the exocrine acini. Each islet is surrounded by connective tissue fibers and penetrated by a network of capillaries. There are four major cell types. The most abundant beta cells (50-80%) secrete INSULIN. Alpha cells (5-20%) secrete GLUCAGON. PP cells (10-35%) secrete PANCREATIC POLYPEPTIDE. Delta cells (~5%) secrete SOMATOSTATIN.	Islands of Langerhans,Islet Cells,Nesidioblasts,Pancreas, Endocrine,Pancreatic Islets,Cell, Islet,Cells, Islet,Endocrine Pancreas,Islet Cell,Islet, Pancreatic,Islets, Pancreatic,Langerhans Islands,Langerhans Islets,Nesidioblast,Pancreatic Islet
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008820	Mice, Obese	Mutant mice exhibiting a marked obesity coupled with overeating, hyperglycemia, hyperinsulinemia, marked insulin resistance, and infertility when in a homozygous state. They may be inbred or hybrid.	Hyperglycemic Mice,Obese Mice,Mouse, Hyperglycemic,Mouse, Obese,Hyperglycemic Mouse,Mice, Hyperglycemic,Obese Mouse
D008861	Microsomes	Artifactual vesicles formed from the endoplasmic reticulum when cells are disrupted. They are isolated by differential centrifugation and are composed of three structural features: rough vesicles, smooth vesicles, and ribosomes. Numerous enzyme activities are associated with the microsomal fraction. (Glick, Glossary of Biochemistry and Molecular Biology, 1990; from Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)	Microsome
D009765	Obesity	A status with BODY WEIGHT that is grossly above the recommended standards, usually due to accumulation of excess FATS in the body. The standards may vary with age, sex, genetic or cultural background. In the BODY MASS INDEX, a BMI greater than 30.0 kg/m2 is considered obese, and a BMI greater than 40.0 kg/m2 is considered morbidly obese (MORBID OBESITY).
D002463	Cell Membrane Permeability	A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.	Permeability, Cell Membrane
D003907	Dexamethasone	An anti-inflammatory 9-fluoro-glucocorticoid.	Hexadecadrol,Decaject,Decaject-L.A.,Decameth,Decaspray,Dexasone,Dexpak,Hexadrol,Maxidex,Methylfluorprednisolone,Millicorten,Oradexon,Decaject L.A.
D005952	Glucose-6-Phosphatase	An enzyme that catalyzes the conversion of D-glucose 6-phosphate and water to D-glucose and orthophosphate. EC 3.1.3.9.	Glucosephosphatase,Glucose 6-Phosphatase,Glucose-6-Phosphate Phosphohydrolase,Glucose 6 Phosphatase
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013045	Species Specificity	The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.	Species Specificities,Specificities, Species,Specificity, Species