Pressure- and volume-induced left ventricular hypertrophies are associated with distinct myocyte phenotypes and differential induction of peptide growth factor mRNAs.

BACKGROUND: Chronic pressure and volume overload (PO and VO) result in morphologically and functionally distinct forms of myocardial hypertrophy. We tested the hypothesis that PO- and VO-induced left ventricular (LV) hypertrophies are associated with distinct molecular phenotypes and patterns of peptide growth factor induction. METHODS AND
RESULTS: mRNA levels were quantified in LV myocardium from rats with LV hypertrophy due to PO or VO caused by suprarenal aortic constriction or an abdominal aortocaval fistula, respectively, for 1 week. Although PO and VO caused comparable increases in LV weight and preproatrial natriuretic factor mRNA, PO but not VO increased mRNA levels for the fetal genes beta-myosin heavy chain and skeletal alpha-actin and reduced the mRNA level of sarcoplasmic reticulum Ca2+ATPase. In a myocyte-enriched myocardial fraction, transforming growth factor-beta 3 and insulin-like growth factor-1 mRNA levels were increased with PO but not VO; acidic fibroblast growth factor mRNA was unchanged with PO but decreased with VO. In a nonmyocyte-enriched myocardial fraction, transforming growth factor-beta 3 and insulin-like growth factor-1 mRNA levels were decreased with VO but unchanged with PO.
CONCLUSIONS: PO- and VO-induced LV hypertrophies are associated with distinct molecular phenotypes and patterns of peptide growth factor induction. Stimulus-specific heterogeneity in the signaling events and peptide growth factors coupled to gene expression could play a role in determining the type of hypertrophy that is caused by various forms of hemodynamic overload.