A previous potassium stimulation enhances the increases of striatal extracellular dopamine and 5-hydroxytryptamine during global ischaemia under simulated penumbral conditions.
The effect of a previous K+ stimulation on striatal extracellular monoamine levels during global ischaemia, under simulated penumbral conditions, was investigated. Rats were implanted with microdialysis probes in both striata, monoamine release was stimulated unilaterally by adding K+ (100 mM, 20 min) to the artificial CSF perfused through one probe, and bilateral partial ischaemia was imposed after monoamine levels had returned to basal values or below. Resultant increases in dialysate levels of dopamine and 5-hydroxytryptamine were markedly and significantly greater on the side previously exposed to K+, even though electrophysiological measurements indicated similarly severe ischaemia on both sides. Associated monoamine metabolite changes did not differ significantly between the two sides. There was no evidence of greater neuronal loss in the K(+)-stimulated striata 7 days after ischaemia. However, striatal tissue probably exposed to the highest concentrations of K+ could not be examined because of extensive gliosis around the probe.
Richards
D A
DA
Department of Neurochemistry, Institute of Neurology, London, England.
Obrenovitch
T P
TP
Johonson-Mora
A
A
Mase
M
M
Symon
L
L
Curzon
G
G
D000818:Animals; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D004298:Dopamine / Q000031:analogs & derivatives / Q000378:metabolism*; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D006719:Homovanillic Acid / Q000378:metabolism; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D002546:Ischemic Attack, Transient / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D008564:Membrane Potentials; D011188:Potassium / Q000494:pharmacology*; D016548:Prosencephalon; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values; D012701:Serotonin / Q000378:metabolism*
D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; C001746:3-methoxytyramine; D011188:Potassium; D004298:Dopamine; D006719:Homovanillic Acid