Studies in postmortem dopamine uptake. I. Kinetic characterization of the synaptosomal dopamine uptake in rat and human brain after postmortem storage and cryopreservation. Comparison with noradrenaline and serotonin uptake.

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The effect of various post-mortem storage times and temperatures on the kinetic parameters of synaptosomal high-affinity dopamine (DA) uptake was studied in rat nucleus accumbens. After post-mortem storage up to 48 hours of rat heads in situ at 22 degrees C the KM data increase moderately in contrast to the Vmax data decreasing rapidly (t1/2 = 30 hours); at 2 degrees C similar changes were observed. The post-mortem changes of the kinetic parameters of noradrenaline (NA) and serotonin (5 HT) uptake were shown in this model to be similar. It is proposed to use this animal model for correcting the kinetic data of DA, NA and 5 HT uptake in human brains regarding the various post-mortem delays. Furthermore, in cryopreservation experiments using a two-step freezing procedure in liquid nitrogen of brain pieces preincubated with dimethylsulfoxide DA uptake of rat and human brain synaptosomes was unchanged after freezing-thawing. The same is true for both NA and 5 HT uptake as demonstrated in human brain tissue. Therefore, post-mortem human brain seems to be suitable for investigating synaptosomal DA, NA, and 5 HT uptake after cryopreservation and correcting for post-mortem delay, when determining kinetic parameters.