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Reflections on what makes the heart grow
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Researchers discovered a digoxin-like substance in rat serum during cardiac overload, suggesting a new cardiotropic factor called endocardin may stimulate heart cell growth.
Area of Science:
- Cardiology
- Endocrinology
- Molecular Biology
Background:
- Cardiac hypertrophy and overload trigger physiological changes in the heart.
- Digoxin-like immunoreactivity has been observed in serum under certain conditions.
- The existence of endogenous cardiotropic factors is under investigation.
Purpose of the Study:
- To investigate the origin of digoxin-like immunoreactivity in experimental cardiac overload.
- To identify a potential endogenous cardiotropic factor involved in cardiac growth.
- To explore the role of this factor in stimulating cardiac myocyte proliferation.
Main Methods:
- Induction of experimental cardiac overload and hypertrophy in rats.
- Measurement of digoxin-like immunoreactivity in serum.
- Assessment of serum's effect on rat cardiac myocyte multiplication in tissue culture.
- Analysis of potential steroid origins.
Main Results:
- Digoxin-like immunoreactivity in rat serum correlated with cardiac growth during overload.
- Sera from overloaded rats stimulated cardiac myocyte proliferation in vitro.
- The factor demonstrated cross-immunoreactivity with digoxin, suggesting a structural similarity.
- The factor is hypothesized to be an adrenal steroid distinct from corticosterone and aldosterone.
Conclusions:
- An endogenous cardiotropic factor, potentially an adrenal steroid, is present during cardiac overload.
- This factor exhibits digoxin-like immunoreactivity and stimulates cardiac myocyte growth.
- The proposed name for this factor is endocardin or endocardiotonin.
Abstract:
Under conditions of experimental cardiac overload and hypertrophy in rats, a digoxinlike immunoreactivity appears in their serum which is correlated with cardiac growth. It is hypothesized that this is caused by the presence of an endogenous cardiotropic factor displaying cross immunoreactivity with digoxin. Additional evidence of the existence of the putative cardiotropic factor is provided by the finding that the sera of rats with cardiac overload displaying digoxinlike immunoreactivity stimulate the multiplication of rat cardiac myocytes in the tissue culture. This factor may be an adrenal steroid different from corticosterone and aldosterone. The name endocardin or endocardiotonin for this substance is suggested.