Induction of c-fos mRNA expression by pure pressure overload in cultured cardiac myocytes.

Mechanical stress by pressure overload due to hypertension or valvular heart disease such as aortic valve stenosis induces cardiac hypertrophy. It has been well established that the mechanical stretch of cardiac myocytes in vitro induces hypertrophic responses such as the expression of immediate early response genes including c-fos. However, it remains uncertain whether the mechanical forces due to pure atmospheric pressure can induce similar responses in cardiac myocytes. We thus cultured rat neonatal cardiac myocytes in an atmospheric pressure chamber apparatus and determined the effects of pure pressure stress on c-fos gene expression. Pressures greater than 80 mmHg enhanced c-fos mRNA after 30 minutes. These results suggest that pure atmospheric pressure overload can also induce early hypertrophic responses in cardiac myocytes.