EFFECT OF ANOXIA ON ISOLATED TURTLE TISSUES - IS THE RESPONSE TO ANOXIA MEDIATED BY PROTEIN-KINASE 2ND MESSENGERS

Organ slices from the turtle Trachemys scripta elegans were incubated under aerobic and anoxic conditions to examine the effect of protein k inase (PrK) second messengers in potentiating the biochemical response s to anoxia exposure. Incubating liver slices from aerobic animals und er anoxic conditions produced biochemical changes exactly similar to t hose observed in vivo: phosphofructokinase (PFK) was more sensitive to citrate inhibition and the percentage of glycogen phosphorylase (GP) in the active a form increased. On the other hand, incubating brain an d heart tissue slices under anoxic conditions produced no changes in P FK and GP kinetic constants. Addition of PrK second messengers (dibuty ryl-cAMP or Ca2+ plus phorbol myristate acetate) to the incubated tiss ues did not promote anoxia-associated changes in aerobically incubated tissues nor did they prevent anoxia-associated changes in anaerobical ly incubated tissues. These results suggest that unidentified external hormonal signals mediate heart and brain responses to anoxia. It is a lso apparent that cAMP and Ca2+ plus phospholipid do not play a role i n bringing about the anoxia-induced changes in PFK, GP and fructose 2, 6-bisphosphate in liver of turtles.