Isoflurane increases the uptake of glutamate in synaptosomes from rat cerebral cortex.
We have studied the effect of increasing concentrations of isoflurane on high- and low-affinity uptake of L-glutamate using synaptosomes from rat cerebral cortex. In the high-affinity uptake range, 0.5% isoflurane had no effect on uptake velocity, while 1.5% and 3.0% isoflurane caused an increase in mean Vmax to 131 (SEM 54) and 210 (103)% of control, respectively. There was no significant change in the K(m) value. Vmax and K(m) values for low-affinity uptake of L-glutamate were unchanged by 1.5% isoflurane. These results provide evidence for an isoflurane-induced increase in high-affinity uptake of glutamate into presynaptic terminals. This effect may contribute to a reduction of transmitter in the synaptic cleft and thereby decreased excitatory synaptic transmission.
Larsen
M
M
Institute for Surgical Research, Rikshospitalet, Oslo, Norway.
Hegstad
E
E
Berg-Johnsen
J
J
Langmoen
I A
IA
D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D018929:Cell Culture Techniques; D002540:Cerebral Cortex / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D018698:Glutamic Acid / Q000378:metabolism*; D007530:Isoflurane / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D009435:Synaptic Transmission / Q000187:drug effects; D013574:Synaptosomes / Q000187:drug effects* / Q000378:metabolism
D018685:Anesthetics, Inhalation; D018698:Glutamic Acid; D007530:Isoflurane