POST‐MORTEM CHANGES IN HIGH AFFINITY CHOLINE UPTAKE

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Abstract
Abstract— When animals were killed by decapitation and the heads kept refrigerated at 2–4°C. high affinity choline uptake was maintained up to 3 days post‐mortem. At 5 days post‐mortem, there was a significant reduction in uptake. In tissues kept at 2–4°C for 1 day, the ionic dependence, drug sensitivity and kinetic parameters of uptake were identical to that of control tissues. At 3 days post‐mortem, intact synaptosomal profiles, although with features characteristic of degenerating neuronal tissues, were observed in electronmicroscopic studies. In tissues maintained at room temperature, however, the uptake activity was nearly completely gone by 1 day. It is concluded that high affinity choline uptake is maintained for days, a surprisingly long time, in tissues kept in the cold immediately after death.When pentylenetetrazol or pentobarbital were administered to rats in order to activate or depress the choline uptake, it was found that the activity‐related changes in choline uptake undergo a reversal in post‐mortem tissues. The changes in uptake were significantly lost by 10min post‐mortem and totally absent by 30min post‐mortem. In vitro studies with whole hippocampi indicate that the postmortem reversal in activity‐related changes in uptake is temperature‐dependent. It is concluded that because of post‐mortem reversals in activity‐related states of uptake the true magnitude of these activity‐related changes in uptake may be underestimated by existing methods of assay. Acetylcholine levels in synaptosomal preparations did not clearly correlate with levels of choline uptake.

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