N-n-Butyl haloperidol iodide (F2), a novel compound derived from
haloperidol, protects against the damaging effects of
ischemia/reperfusion (I/R) injury in vitro and in vivo. We tested whether the myocardial protection of F2 on cardiomyocyte
hypoxia/reoxygenation (H/R) injury is mediated by modulating
protein kinase C (PKC) activity in primary cultured cardiomyocytes. Primary cultures of ventricular cardiomyocytes underwent 2-h
hypoxia and 30-min reoxygenation. Total PKC activity was measured, and the translocation pattern of PKCalpha, betaII, delta and epsilon
isoforms was assessed by fractionated western blot analysis. We investigated the association of PKC
isoform translocation and H/R-induced injury in the presence and absence of the specific inhibitors and activator. Measurements included cell damage evaluated by
creatine kinase (CK) release, and apoptosis measured by
annexin V-FITC assay. In primary cultured cardiomyocytes exposed to H/R, PKCalpha, delta and epsilon were translocated, with no change in PKCbetaII activity. Total PKC activity, CK release and apoptosis were increased after H/R. Treatment with the conventional PKC inhibitor
Go6976 reduced early growth response-1 (Egr-1)
protein expression and attenuated apoptosis. The PKCepsilon inhibitor
peptide epsilonV1-2 increased H/R injury without influencing Egr-1 expression. Pretreatment with F2 inhibited translocation of PKCalpha, increased translocation of PKCepsilon, and relieved the CK release and apoptosis. The protection of F2 was blocked in part by the conventional PKC activator
thymeleatoxin (TXA) and
epsilonV1-2 peptide. F2 significantly alleviated H/R-induced injury, which might be attributed to the combined benefits of inhibiting PKCalpha and activating PKCepsilon.