ALTERED EXPRESSION OF ATRIAL-NATRIURETIC-PEPTIDE AND CONTRACTILE PROTEIN GENES IN HYPERTROPHIED VENTRICLE OF JVS MICE WITH SYSTEMIC CARNITINE DEFICIENCY

To characterize cardiac hypertrophy in juvenile visceral steatosis (JV S) mice with systemic carnitine deficiency, we investigated how the hy pertrophy develops and whether it is associated with altered expressio n of any specific genes, especially atrial natriuretic peptide (ANP) a nd contractile protein genes, in the hypertrophied ventricle. Cardiac hypertrophy in JVS mice became apparent at 10 days after birth and pro gressed during development. The hypertrophy was observed in the ventri cles but not in the atria. ANP mRNA was more intensively expressed in JVS ventricles than in control even at 5 days. Carnitine administratio n ameliorated the cardiac hypertrophy and suppressed the augmentation of ANP mRNA in the ventricles. Isoform change of expression of alpha-a ctin genes from cardiac to skeletal was seen in the ventricles of JVS mice at 2 weeks. There was no difference in the ratio of beta-myosin h eavy chain mRNA to alpha-myosin heavy chain mRNA between control and T VS mice at 5 days, but at 2 weeks the ratio was significantly lower in JVS mice than in control. These results suggest that the molecular ch aracteristics of cardiac hypertrophy caused by carnitine deficiency ar e different from those of cardiac hypertrophy caused by aortic constri ction. (C) 1997 Academic Press Limited.