Effects of damaging the endocardial surface on the mechanical performance of isolated cardiac muscle.

Author:

Brutsaert D L1,Meulemans A L1,Sipido K R1,Sys S U1

Affiliation:

1. Department of Physiology and Medicine, University of Antwerp, Belgium.

Abstract

The mechanical properties of mammalian ventricular cardiac muscle have been studied in the presence and in the absence of an intact endocardial surface. Isotonic and isometric twitch contractions were obtained from papillary muscles of the right ventricle of cat at 29 degrees and 37 degrees C, at different extracellular calcium concentrations ([Ca2+]o), and at different initial muscle lengths. The endocardial surface was damaged by gentle abrasion of the muscle surface with a plastic blade or by brief immersion for 1 second with 1% Triton X-100. Although there was no evidence of damage to myocardial cells, damaging the endocardial surface resulted in an immediate and irreversible abbreviation of the twitch contractions with, except at the highest ([Ca2+]o, a decrease in peak isometric twitch tension. These changes induced 1) an asymmetrical shift of the tension-[Ca2+]o relation towards increasing [Ca2+]o but with no effect at the highest [Ca2+]o, and 2) a rightward and downward shift of the length-tension relation. Both shifts were significantly more pronounced at 37 degrees C than at 29 degrees C; they were not accompanied by significant changes in Vmax. The asymmetrical shift of the tension-[Ca2+]o relation suggests that the endocardium-mediated chain of events may be mediated by changes in the sensitivity of the contractile proteins to Ca2+. This hypothesis is also supported by the similar pattern of changes (i.e., modulation of the onset of early tension decline) induced by decreasing length at each [Ca2+]o and by the removal of a functional endocardium. Accordingly, the endocardium may help to control the performance of the heart by modulating peak contractile performance and relaxation of the underlying myocardium.

Publisher

Ovid Technologies (Wolters Kluwer Health)

Subject

Cardiology and Cardiovascular Medicine,Physiology

Reference27 articles.

1. Ultrastructure of the normal atrial endocardium.

2. MelaxH.LeesonTS: Fine structure of the endocardium in adult rats. Cardiovasc Res 1967;l:349-355

3. Lindenfelser R: Die Oberflache des Endokards des Rattenherzens;Buss H;Rasterelektronenmikroskopische Untersuchungen. Beitr Path Bd,1973

4. A study of endocardial endothelium using freeze-drying and scanning electron microscopy;Wheeler EE;AnatRec,1973

5. Intercellular junction of rat endocardium;Anversa P;AnatRec,1975

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