REEMERGENCE OF THE FETAL PATTERN OF L-TYPE CALCIUM-CHANNEL GENE-EXPRESSION IN NONINFARCTED MYOCARDIUM DURING LEFT-VENTRICULAR REMODELING

The cardiac L-type voltage-dependent calcium channel (VDCC) is a criti cal component of cardiac action potential and excitation-contraction c oupling. The objective of the present study was to examine the changes in expression in Motif IV, an alternatively spliced region of the alp ha-1 subunit of the VDCC channel in post-myocardial infarction (MI) re modeled rat left ventricle. RNase protection assay was used to determi ne alteration in isoform expression in the noninfarcted hypertrophied ventricular myocardium 21 days post myocardial infarction. Our study d emonstrates that cardiac hypertrophy is associated with significant in crease in the mRNA level of the fetal isoform, with the reversion of f etal:adult isoform ratio to the fetal phenotype. Changes in isoform ex pression in the post-MI remodeled ventricle, not previously reported, is a pertinent genetic marker of cardiac hypertrophy. (C) 1995 Academi c Press, Inc.