Fast skeletal muscle troponin T increases the cooperativity of transgenic mouse cardiac muscle contraction

Qi Quan Huang, Frank V. Brozovich, Jian Ping Jin

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

1. To investigate the functional significance of different troponin T (TnT) isoforms in the Ca2+ activation of muscle contraction, transgenic mice have been constructed with a chicken fast skeletal muscle TnT transgene driven by a cardiac α-myosin heavy chain gene promoter. Cardiac muscle-specific expression of the fast skeletal muscle TnT has been obtained with significant myofibril incorporation. Expression of the endogenous cardiac muscle thin filament regulatory proteins, such as troponin I and tropomyosin, was not altered in the transgenic mouse heart, providing an authentic system for the functional characterization of TnT isoforms. 3. Cardiac muscle coatractility was analysed for the force vs. Ca2+ relationship in skinned ventricular trabeculae of transgenic mice in comparison with wild-type litter-mates. The results showed unchanged pCa50 values (5.1 ± 0.04 and 5.1 ± 0.1, respectively) but significantly steeper slopes (the Hill coefficient was 2.0 ± 0.2 vs. 1.0 ± 0.2, P < 0.05). 4. The results demonstrate that the structural and functional variation of different TnT isoforms may contribute to the difference in responsiveness and overall cooperativity of the thin filament-based Ca2+ regulation between cardiac and skeletal muscles.

Original languageEnglish (US)
Pages (from-to)231-242
Number of pages12
JournalJournal of Physiology
Volume520
Issue number1
DOIs
StatePublished - Oct 1 1999

ASJC Scopus subject areas

  • Physiology

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