Key result
Mechanical stretch increases ANP mRNA ~3-fold in isolated rat papillary muscles independent of circulating factors.
Why the study?
The effect of mechanical stretch on protein synthesis and atrial natriuretic peptide gene expression in isolated rat papillary muscles was not fully understood.
Does mechanical stretch increase ANP gene expression in isolated rat papillary muscles?
Does mechanical stretch increase ANP gene expression in isolated rat papillary muscles?
Effect estimate: more than threefold increase
Mechanical stretch rapidly induces ANP gene expression in isolated rat papillary muscles independent of circulating or nervous factors, suggesting potential local actions of ventricular ANP.
Indicates local ventricular ANP regulation by stretch; leaves open translation to human pathophysiology or therapy.
The effect of mechanical stretch on protein synthesis and the expression of the gene for atrial natriuretic peptide (ANP) was examined in electrically paced, isolated papillary muscles from rat heart. Incorporation of [3H]phenylalanine into protein increased only in stretched but not in unloaded muscles. Five hours of stretching increased ANP mRNA levels more than threefold as compared to freshly excised papillary muscles. A drastic fall in ANP mRNA levels was observed in unloaded muscles over this time. These data indicate that papillary muscles similar to other ventricular tissue are capable of activating ANP gene expression in response to increased load. The effect occurs in vitro and does not depend on circulating or nervous factors. The unexpected rapid induction of ANP gene expression in such a particular structure of the heart raises the possibility of local actions of ventricular ANP.
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Jarygin et al. (1994) studied this question. Mechanical stretch vs. unloaded muscles and freshly excised papillary muscles was evaluated on Protein synthesis and expression of the gene for atrial natriuretic peptide (ANP) (more than threefold increase). Mechanical stretch of isolated rat papillary muscles for five hours increased ANP mRNA levels more than threefold compared to freshly excised muscles, independent of circulating or nervous factors.
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