Effects of volatile anesthetics on glutamate transporter, excitatory amino acid transporter type 3: the role of protein kinase C

Anesthesiology. 2002 Jun;96(6):1492-7. doi: 10.1097/00000542-200206000-00032.


Background: Glutamate transporters play an important role in maintaining extracellular glutamate homeostasis. The authors studied the effects of volatile anesthetics on one type of glutamate transporters, excitatory amino acid transporter type 3 (EAAT3), and the role of protein kinase C in mediating these effects.

Methods: Excitatory amino acid transporter type 3 was expressed in Xenopus oocytes by injection of EAAT3 mRNA. Using two-electrode voltage clamp, membrane currents were recorded before, during, and after application of L-glutamate. Responses were quantified by integrating the current trace and are reported as microcoulombs. Data are mean +/- SEM.

Results: L-Glutamate-induced responses were increased gradually with the increased concentrations of isoflurane, a volatile anesthetic. At 0.52 and 0.70 mm isoflurane, the inward current was significantly increased compared with control. Isoflurane (0.70 mm) significantly increased Vmax (maximum velocity) (3.6 +/- 0.4 to 5.1 +/- 0.4 microC; P < 0.05) but not Km (Michoelis-Menten Constant) (55.4 +/- 17.0 vs. 61.7 +/- 13.6 microm; P > 0.05) of EAAT3 for glutamate compared with control. Treatment of the oocytes with phorbol-12-myrisate-13-acetate, a protein kinase C activator, caused a significant increase in transporter current (1.7 +/- 0.2 to 2.5 +/- 0.2 microC; P < 0.05). Responses in the presence of the combination of phorbol-12-myrisate-13-acetate and volatile anesthetics (isoflurane, halothane, or sevoflurane) were not greater than those when volatile anesthetic was present alone. Oocytes pretreated with any of the three protein kinase C inhibitors alone (chelerythrine, staurosporine, or calphostin C) did not affect basal transporter current. Although chelerythrine did not change the anesthetic effects on the activity of EAAT3, staurosporine or calphostin C abolished the anesthetic-induced increase of EAAT3 activity.

Conclusions: These data suggest that volatile anesthetics enhance EAAT3 activity and that protein kinase C is involved in mediating these anesthetic effects.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Transport System X-AG*
  • Anesthetics, Inhalation / pharmacology*
  • Animals
  • Carrier Proteins / drug effects*
  • Carrier Proteins / genetics
  • Carrier Proteins / physiology
  • Dose-Response Relationship, Drug
  • Enzyme Activation
  • Female
  • Glutamate Plasma Membrane Transport Proteins
  • Glutamic Acid / metabolism
  • Protein Kinase C / physiology
  • Symporters*
  • Tetradecanoylphorbol Acetate / pharmacology
  • Xenopus laevis


  • Amino Acid Transport System X-AG
  • Anesthetics, Inhalation
  • Carrier Proteins
  • Glutamate Plasma Membrane Transport Proteins
  • Symporters
  • Glutamic Acid
  • Protein Kinase C
  • Tetradecanoylphorbol Acetate