Phospholipase C (PLC) influences cardiac function. This study examined PLC
isozymes of the cardiac sarcolemma (SL) membrane and in the cytosol compartment in isolated perfused rat hearts subjected to global
ischemia for 30 min followed by up to 30 min of reperfusion. Although the total SL PLC activity was decreased in
ischemia and increased upon reperfusion, differential changes in PLC
isozymes were detected.
PLC beta(1)
mRNA and SL
protein abundance and activity were increased in
ischemia, with concomitant decreases in activity and
protein level in the cytosol. On the other hand, upon reperfusion,
PLC beta(1) activity was decreased, but remained higher than control values. Although no change in the PLC delta(1)
mRNA level in
ischemia was detected, SL PLC delta(1) activity and content were depressed. Furthermore, in the cytosol, PLC delta(1) activity was increased, but the
protein level decreased. SL
PLC gamma(1) activity was decreased, independent of gene expression and
protein content; however, decreases in the activity and
protein abundance were detected in the cytosol. Increases in
PLC gamma(1) and delta(1) activities occurred upon reperfusion, but were not accounted for by altered
mRNA and
protein levels. The results indicate that
ischemia-reperfusion induces differential changes in PLC
isozymes.