We investigated which PKC isoforms are involved in high glucose-induced protection against hypoxic injury. Treatment for 48 h with high glucose (22 mM) markedly increased the expression of PKC-epsilon in the particulate fraction (213+/-22.1% of the control) but had no effect on other types of PKC isoforms, suggesting that the high glucose-induced increase in PKC expression is isoform-specific. The mRNA level for PKC-epsilon was also substantially increased, reaching its peak after 4 h of high glucose treatment. The high glucose increased PKC-epsilon activity in the particulate fraction up to 183+/-32.2% of the control. During hypoxia, the amount of PKC-epsilon in the particulate fraction was remarkably diminished in the low glucose-treated cells, but remained at a higher level in high glucose-treated cells. The treatment with epsilonV1-2 (10 muM), a specific inhibitor of PKC-epsilon, abolished the protective effect of high glucose against hypoxia. These results suggest that isoform-specific induction of PKC-epsilon is involved in high glucose-induced protection against hypoxic injury in heart-derived H9c2 cells. (C) 2003 Elsevier Inc. All rights reserved.