Postmortem- and cryostability of the potassium-evoked release of [3H]5-hydroxytryptamine from rat cerebral cortical miniprisms.
A prerequisite for the study of neurotransmitter release from human brain autopsy samples with histories of different diseases is that the cryo- and postmortem stability of the release process is good. In the present study, the effect of post-mortem delay and of storage at -70 degrees C by the "slow freeze--fast thaw" method of Hardy et al. [J Neurochem (1983) 40: 608-614] (which allows for the retention of metabolic activity of the tissue after the storage and thawing) of rat cerebral cortex samples upon the release of [3H]5-hydroxytryptamine ([3H]5-HT) from prelabelled miniprisms has been investigated. Storage of samples at -70 degrees C by this method resulted in samples that accumulated less [3H]5-HT but showed an increased sensitivity to the Ca2+-dependent releasing properties of K+ when compared with "fresh" samples. On the other hand, the sensitivity of the K+-evoked release to the inhibitory effects of the serotoninergic agonist 5-methoxy-N,N-dimethyltryptamine were reduced by storage. The effects on [3H]5-HT accumulation and on K+-evoked release were due mainly to the freeze-thaw procedure, the length of storage at -70 degrees C having only a minor influence on these parameters. A post-mortem interval of 5 hours at either +4 or +22 degrees C prior to storage of the tissue reduced the K+-evoked release of tritium, but did not affect the accumulation of [3H]5-HT or the inhibitory effects of 5-methoxy-N,N-dimethyltryptamine on the K+-evoked release over and above the effects produced by the storage per se.
Fowler
C J
CJ
Department of Geriatric Medicine, Karolinska Institutet, Huddinge Sjukhus, Sweden.
Thorell
G
G
Fagervall
I
I
D000818:Animals; D002118:Calcium / Q000502:physiology; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D005615:Freezing; D008297:Male; D011180:Postmortem Changes; D011188:Potassium / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000378:metabolism*; D013997:Time Factors; D014021:Tissue Preservation
D012701:Serotonin; D011188:Potassium; D002118:Calcium