Regulation of the glutamine content of astrocytes by cAMP and hydrocortisone: effect of pH.
It was reported recently that the glutamine content of astrocytes incubated with glutamate and ammonium is steeply dependent on the pH of the solution. The present study shows that pretreatment of astrocytes with dibutyryl cAMP or with hydrocortisone, conditions that induce glutamine synthetase activity, increased glutamine content 2.4-fold and 5.3-fold, respectively. Nevertheless, a shift of pH from 7.4 to 7.8 increased glutamine content further by 2.7-fold and 3.0-fold, respectively. The net rates of uptake of glutamate and export of glutamine varied narrowly compared to these very large changes in glutamine content.
Brookes
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Department of Pharmacology and Experimental Therapeutics, University of Maryland School of Medicine, Baltimore 21201.
D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D003994:Bucladesine / Q000494:pharmacology; D000242:Cyclic AMP / Q000494:pharmacology*; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D005973:Glutamine / Q000378:metabolism*; D006854:Hydrocortisone / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D051379:Mice; D000644:Quaternary Ammonium Compounds / Q000378:metabolism
D005971:Glutamates; D000644:Quaternary Ammonium Compounds; D005973:Glutamine; D018698:Glutamic Acid; D003994:Bucladesine; D000242:Cyclic AMP; D005974:Glutamate-Ammonia Ligase; D006854:Hydrocortisone