FORCE PCA RELATION AND TROPONIN-T ISOFORMS OF RABBIT MYOCARDIUM

被引:101
作者
NASSAR, R
MALOUF, NN
KELLY, MB
OAKELEY, AE
ANDERSON, PAW
机构
[1] DUKE UNIV, MED CTR, DEPT PEDIAT, POB 3218, DURHAM, NC 27710 USA
[2] DUKE UNIV, MED CTR, DEPT CELL BIOL, DURHAM, NC 27710 USA
[3] UNIV N CAROLINA, DEPT PATHOL, CHAPEL HILL, NC 27514 USA
关键词
THIN FILAMENT REGULATORY PROTEINS; MYOFILAMENTS; HEART; CALCIUM;
D O I
10.1161/01.RES.69.6.1470
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
We have previously reported the existence of at least four troponin T isoforms in rabbit ventricular muscle and described the changes in their distribution with development. In this report we test whether the Proportions of the troponin T isoforms are related to the sensitivity of the myofilaments to calcium. We measured the force-pCa relations in 12 detergent-skinned ventricular strands of cardiac muscle from newborn (2-5-day-old) rabbits. We determined from each strand the amount of each troponin T isoform relative to the total amount of troponin T by using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and densitometric scans of Western blots probed with a cardiac-specific troponin T monoclonal antibody, MAb 13-11. To assess the presence of different relative amounts of cardiac and slow skeletal troponin I among the strands, we determined the amount of cardiac troponin I relative to tropomyosin. We determined the Hill coefficient and the pCa for half-maximal force, pCa50, for each strand. pCa50 was related directly to the relative amount of troponin T2 (p(slope) = 0.037). Our results do not indicate a relation between the Hill coefficient and troponin T2. We also did not find a relation between pCa50 and the cardiac troponin I/tropomyosin ratio, which suggests that the correlation between pCa50 and troponin T2 was not a result of changes in the relative amounts of cardiac and slow skeletal muscle troponin 1. Our findings indicate that a relation exists between the force-pCa characteristics of rabbit myocardium and the troponin T isoforms that it expresses, suggesting a role for troponin T in modulating the sensitivity of cardiac myofilaments to calcium.
引用
收藏
页码:1470 / 1475
页数:6
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