Inhibition of
angiotensin-converting enzyme (ACEI) after
myocardial infarction reduces remodeling of the surviving myocardium. The cellular signaling mechanisms contributing to remodeling are not fully elucidated. Goal of the current study was to test whether
protein kinase C (PKC) is regulated in the surviving myocardium shortly after
infarction and whether this regulation is influenced by ACEI. Rats were subjected to
anterior wall myocardial infarction in vivo or
sham operation. After 15-45 min,
mRNA levels and
protein expression of the major cardiac PKC
isoforms were measured in the ischemic and the remote myocardium. The influence of ACEI on PKC was tested by pretreating the rats with
ramiprilat. In the ischemic region of the myocardium, a significant increase of the
mRNA for PKC-delta and
PKC-epsilon was observed in close correlation with increased
isoform protein expression. In the surviving, remote myocardium, however, only
PKC-epsilon expression was significantly augmented both at the
mRNA level (158%) and at the
protein level (149%). PKC-delta and PKC-alpha were unchanged. Treatment with
ramiprilat could abolish this
isoform-specific PKC regulation in both areas. These data characterize for the first time an
isoform-specific transcriptional regulation process of PKC in the surviving myocardium after
infarction. This induction of
PKC-epsilon can be prevented by ACEI. It is speculated that
PKC-epsilon plays a role in the signal transduction of early remodeling after
infarction.