The incorporation of 14C-leucine into the post-mitochondrial supernatant and neuron, glia and myelin-enriched fractions isolated from the rabbit spinal cord was studied after ischaemia and subsequent recirculation. In the cell-free system, incorporation decreased to 55% of the control value after 40 min ischaemia, but proteosynthesis returned to the pre-ischaemic value after 3 h recirculation and remained at this level during further recirculation. The incorporation of amino acids into proteins of neurons and neuroglia differed from the cell-free system and from each other. In the enriched neuronal fraction, protein synthesis fall after ischaemia and also during the first hours of recirculation, but during further recirculation it rose to 60% above the control value. In the enriched glial fraction, specific radioactivity of proteins rose abruptly immediately after ischaemia and by the fourth day there was sixfold increase as compared with control values. The results indicate that the ischaemia-induced decrease in protein synthesis is only transient and that a significant increase occurs in the surviving cell populations, especially the neuroglia. The functional changes caused by spinal cord ischaemia are irreversible, however.

Institute of Neurobiology Slovak Academy of Sciences Kosice