The effects of anaesthetics on the uptake and release of amino acid neurotransmitters in thalamic slices.
1 The effect of thiopentone, methohexitone, urethane and ketamine on the uptake and release of gamma-aminobutyric acid (GABA) and D-aspartate by rat thalamic slices has been investigated. 2 A high, supra-anaesthetic concentration of methohexitone increased the uptake of both D-aspartate and GABA. 3 None of the anaesthetics used had any detectable effect upon the spontaneous release of either amino acid. 4 Urethane and ketamine had no effect upon the K+-stimulated release of either amino acid. 5 Methohexitone and thiopentone produced a biphasic dose-response on the K+-stimulated release of both amino acids; low concentrations enhanced release, high concentrations depressed release. 6 Bicuculline hydrochloride and picrotoxin both significantly reduced the barbiturate-induced enhancement of K+-stimulated amino acid release, but did not significantly alter the depression of K+-stimulated release at higher barbiturate concentrations. 7 Baclofen, either alone (1 microM to 1 mM), or tested against the barbiturates, had no detectable effect.
D000777:Anesthetics / Q000494:pharmacology*; D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism*; D001418:Baclofen / Q000494:pharmacology; D001640:Bicuculline / Q000494:pharmacology; D002118:Calcium / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D008723:Methohexital / Q000494:pharmacology; D018377:Neurotransmitter Agents / Q000378:metabolism*; D010852:Picrotoxin / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013788:Thalamus / Q000187:drug effects* / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D000777:Anesthetics; D001224:Aspartic Acid; D001418:Baclofen; D001640:Bicuculline; D002118:Calcium; D008723:Methohexital; D018377:Neurotransmitter Agents; D010852:Picrotoxin; D011188:Potassium; D005680:gamma-Aminobutyric Acid