A sensitive radioisotopic assay of myo-inositol: its application to rat pancreatic islets.
A radioisotopic procedure for the assay of myo-inositol is presented. It is based on the generation of NADH from NAD+ in the reaction catalyzed by myo-inositol dehydrogenase and the subsequent NADH-dependent conversion of 2-[U-14C]ketoglutarate to 14C-labeled L-glutamate in the reaction catalyzed by glutamate dehydrogenase. This method was applied to the measurement of myo-inositol in rat pancreatic islets. The myo-inositol islet content was decreased when the animals were fed a diet deprived of myo-inositol. When incubated in the absence of exogenous D-glucose, pancreatic islets, like parotid cells, released myo-inositol in the incubation medium. Over 90 min of incubation, a rise in extracellular D-glucose concentration increased the myo-inositol islet content, which was decreased, however, after incubation in the presence of carbamylcholine. These findings indicate that the myo-inositol content of islets is affected by nutritional and other environmental factors.
Sener
A
A
Laboratory of Experimental Medicine, Brussels Free University, Belgium.
Ramirez
R
R
Malaisse
W J
WJ
D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D002250:Carbon Radioisotopes; D005947:Glucose / Q000494:pharmacology; D005971:Glutamates / Q000378:metabolism*; D006019:Glycolysis / Q000187:drug effects; D066298:In Vitro Techniques; D007294:Inositol / Q000032:analysis* / Q000378:metabolism / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D007656:Ketoglutaric Acids / Q000378:metabolism*; D007700:Kinetics; D007908:Lens, Crystalline / Q000378:metabolism; D009928:Organ Specificity; D010306:Parotid Gland / Q000378:metabolism; D011865:Radioisotope Dilution Technique; D051381:Rats; D011919:Rats, Inbred Strains
D002250:Carbon Radioisotopes; D005971:Glutamates; D007328:Insulin; D007656:Ketoglutaric Acids; D007294:Inositol; D002217:Carbachol; D005947:Glucose