Force-pCa relation and troponin T isoforms of rabbit myocardium.

Abstract

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 (pslope = 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 I. 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.

4 Figures and Tables

Statistics

050100'95'98'01'04'07'10'13'16
Citations per Year

570 Citations

Semantic Scholar estimates that this publication has 570 citations based on the available data.

See our FAQ for additional information.

Cite this paper

@article{Nassar1991ForcepCaRA, title={Force-pCa relation and troponin T isoforms of rabbit myocardium.}, author={Rashid Nassar and Nadia N. Malouf and Matthew B. Kelly and Annette E Oakeley and Page A. W. Anderson}, journal={Circulation research}, year={1991}, volume={69 6}, pages={1470-5} }