Developmental changes in contractility and sarcomeric proteins from the early embryonic to the adult stage in the mouse heart

• DOI: 10.1113/jphysiol.2002.036509
• Publication Date: 2003-04-14T23:33:51Z
• Authors: S. Siedner; M. Kruger; M. Schroeter; D. Metzler; W. Roell; B. K Fleischmann; J. Hescheler; G. Pfitzer; R. Stehle
• Keywords: Contractility; Troponin T; Myofilament; Troponin complex; Troponin C

Developmental changes in force-generating capacity and Ca2+ sensitivity of contraction murine hearts were correlated with myosin heavy chain (MHC) troponin (Tn) isoform expression, using Triton-skinned fibres. The maximum Ca2+-activated isometric force normalized to the cross-sectional area (FCSA) increased mainly during embryogenesis continued increase at a slower rate until adulthood. During prenatal development, FCSA about 5-fold from embryonic day (E)10.5 E19.5, while amount MHC total protein remained constant (from E13.5 E19.5). This suggests that development structural organization myofilaments fetal period may play an important role for improvement generation. There was overall decrease 0.5 pCa units generation adult, which main (0.3 units) occurred within short time interval, between E19.5 7 days after birth (7 pn). Densitometric analysis SDS-PAGE Western blots revealed major switches T (TnT) isoforms occur before E16.5, whereas transition points slow skeletal I (ssTnI) cardiac TnI (cTnI) beta-MHC alpha-MHC both around birth, temporal correlation sensitivity. To test whether are solely based on Tn, native Tn complex replaced fibres adult fast (fsTn) purified rabbit muscle. difference pre-replacement values pCa50 (-log([Ca2+] M-1)) required half-maximum development) (6.05 +/- 0.01) (5.64 0.04) fully abolished replacement exogenous (pCa50 = 6.12 0.05 stages). developmental skinned myocardium originate primarily switch ssTnI cTnI.