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

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