title: Effect of helium and heliox on glutamate decarboxylase activity.
abstract: The activity of glutamate decarboxylase (GAD) in pure helium at 6.8 MPa was significantly enhanced when compared to GAD activity in air at 0.1 MPa (906 vs. 602 nmol.h-1.mg-1 protein, respectively). No significant difference was found between GAD activities in heliox at 6.8 MPa (0.87% O2 at 6.8 MPa) and in air at 0.1 MPa. On the other hand, the activities in heliox at 0.1 MPa (0.87% O2 at 0.1 MPa) and air at 0.1 MPa were significantly different (655 and 446 nmol.h-1.mg-1 protein, respectively). These data indicate that pressures up to 6.8 MPa do not affect the GAD-catalyzed synthesis of gamma-aminobutyric acid, but that the enzyme, as previously reported, is sensitive to low levels of oxygen.
authors.affiliation: Diving Medicine Department, Naval Medical Research Institute, Bethesda, Maryland 20814-5055.
authors.forename: J S
authors.initials: JS
authors.lastname: Colton
authors.forename: S C
authors.initials: SC
authors.lastname: Gilman
authors.forename: P
authors.initials: P
authors.lastname: Chang
authors.forename: C A
authors.initials: CA
authors.lastname: Colton
mesh_terms: D000818:Animals; D001274:Atmospheric Pressure; D003509:Cyclohexanecarboxylic Acids / Q000494:pharmacology; D018756:GABA Antagonists; D005968:Glutamate Decarboxylase / Q000378:metabolism*; D006168:Guinea Pigs; D006371:Helium / Q000494:pharmacology*; D006610:High Pressure Neurological Syndrome / Q000201:enzymology / Q000503:physiopathology; D066298:In Vitro Techniques; D008297:Male; D018377:Neurotransmitter Agents / Q000378:metabolism; D010100:Oxygen / Q000494:pharmacology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D003509:Cyclohexanecarboxylic Acids; D018756:GABA Antagonists; D018377:Neurotransmitter Agents; D006371:Helium; C012987:gabaculine; D005680:gamma-Aminobutyric Acid; C038949:heliox; D005968:Glutamate Decarboxylase; D010100:Oxygen