Determination of hippocampal protein kinase C using a frozen tissue method: comparison of synaptosomal and total activity in C57BL/6 and DBA/2 mice.

A slow freeze/fast thaw tissue preparation gave analogous hippocampal protein kinase C (PKC) activity to a fresh tissue preparation in both C57BL/6 and DBA/2 mice. Both the frozen and fresh preparations demonstrated a 28% reduction in membrane-bound PKC activity in DBA compared to C57 mice which supports our previous findings (14). This DBA-associated reduction was found only in total PKC and not synaptosomal PKC activity suggesting that the PKC difference between C57 and DBA mice may be primarily postsynaptic. This investigation shows that (1) PKC activity obtained from a slow freeze/fast thaw preparation is analogous to activity obtained from fresh tissue and (2) analysis of PKC activity in both a total and synaptosomal preparation may provide additional characterization of PKC differences such as that observed between C57 and DBA mice.