scholarly journals The effects of slow skeletal troponin I expression in the murine myocardium are influenced by development-related shifts in myosin heavy chain isoform

2012 ◽  
Vol 590 (23) ◽  
pp. 6047-6063 ◽  
Author(s):  
Steven J. Ford ◽  
Murali Chandra
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Troponin I ◽  
Myosin Heavy Chain Isoform ◽  
Slow Skeletal Troponin I

Abstract 19086: Myofilament Proteins of the Naked Mole-rat Heart Reflect Low Basal Species Cardiac Function

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Kelly M Grimes ◽  
David Barefield ◽  
Mohit Kumar ◽  
Pieter P de Tombe ◽  
Sakthivel Sadayappan ◽  
...  
Keyword(s):  
Cardiac Function ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Troponin I ◽  
Myocardial Contraction ◽  
Myosin Heavy Chain Isoform ◽  
Mole Rat ◽  
Naked Mole Rat ◽  
And Function

The naked mole-rat (NMR) is a mouse-sized rodent with a maximum longevity of >31 years. The species exhibits low basal heart rate (256 bpm) and cardiac output (7 ml/min) for its body size, as well as low fractional shortening (28%) for a rodent. However unlike other well-studied mammals, the NMR maintains cardiac reserve and diastolic function for at least 75% of its maximum lifespan - at ages equivalent to 90 year old humans. We questioned if this low basal cardiac function was due to NMR myofilament composition and function. NMR ventricles are comprised primarily of the β-myosin heavy chain isoform, which is associated with slowed myocardial contraction and increased efficiency. This is in stark contrast to mouse ventricles, which express predominately the α-isoform, and switch to the β-isoform upon experimental induction of heart failure. Compared to mice, NMR myofilament proteins such as cardiac troponin I and cardiac myosin binding protein-C display lower levels of phosphorylation. Such levels are indicative of decreased activation of myofilament proteins and may relate to the species’ low basal cardiac function. Both the NMR’s predominance of β-myosin heavy chain and the low basal level of myofilament phosphorylation present a phenotype much closer to that seen in human ventricles than in those of mice. Intriguingly, maximal force developed by skinned NMR cardiomyocytes is not significantly different to that of mouse cardiomyocytes (NMR: 70.9 ± 9.3mN/mm2 vs. mouse: 87.7 ± 0.6 mN/mm2). This is likely a reflection of the NMR’s ability to enhance cardiac function to the level of a mouse when stimulated, as is evident when both species are treated in vivo with dobutamine (3 μg/g i.p.). Such low basal cardiac function may put less overall strain on the heart over time and could be critical to the NMR’s ability to maintain cardiac function with age.

scholarly journals The Drosophila indirect flight muscle myosin heavy chain isoform is insufficient to transform the jump muscle into a highly stretch-activated muscle type

2017 ◽  
Vol 312 (2) ◽  
pp. C111-C118 ◽  
Author(s):  
Cuiping Zhao ◽  
Douglas M. Swank
Keyword(s):  
Power Generation ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Flight Muscle ◽  
Fold Increase ◽  
Isometric Tension ◽  
Indirect Flight Muscle ◽  
Muscle Type ◽  
Myosin Heavy Chain Isoform ◽  
Muscle Types

Stretch activation (SA) is a delayed increase in force that enables high power and efficiency from a cyclically contracting muscle. SA exists in various degrees in almost all muscle types. In Drosophila, the indirect flight muscle (IFM) displays exceptionally high SA force production ( FSA), whereas the jump muscle produces only minimal FSA. We previously found that expressing an embryonic (EMB) myosin heavy chain (MHC) isoform in the jump muscle transforms it into a moderately SA muscle type and enables positive cyclical power generation. To investigate whether variation in MHC isoforms is sufficient to produce even higher FSA, we substituted the IFM MHC isoform (IFI) into the jump muscle. Surprisingly, we found that IFI only caused a 1.7-fold increase in FSA, less than half the increase previously observed with EMB, and only at a high Pi concentration, 16 mM. This IFI-induced FSA is much less than what occurs in IFM, relative to isometric tension, and did not enable positive cyclical power generation by the jump muscle. Both isometric tension and FSA of control fibers decreased with increasing Pi concentration. However, for IFI-expressing fibers, only isometric tension decreased. The rate of FSA generation was ~1.5-fold faster for IFI fibers than control fibers, and both rates were Pi dependent. We conclude that MHC isoforms can alter FSA and hence cyclical power generation but that isoforms can only endow a muscle type with moderate FSA. Highly SA muscle types, such as IFM, likely use a different or additional mechanism.

Effect of Dietary Creatine on Skeletal Muscle Myosin Heavy Chain Isoform Expression in an Animal Model of Uremia

2004 ◽  
Vol 96 (4) ◽  
pp. e103-e110 ◽  
Author(s):  
Youri E.C. Taes ◽  
Marijn Speeckaert ◽  
Evelien Bauwens ◽  
Marc R. De Buyzere ◽  
Johan Libbrecht ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Animal Model ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Skeletal Muscle Myosin ◽  
Myosin Heavy Chain Isoform ◽  
Isoform Expression ◽  
Muscle Myosin

scholarly journals Myosin heavy chain isoform profiles remain altered at 7 months if the lacerated medial gastrocnemius is poorly reinnervated: A study in rabbits

2009 ◽  
Vol 28 (6) ◽  
pp. 732-738 ◽  
Author(s):  
Barry P. Pereira ◽  
Hwan Chour Han ◽  
Zou Yu ◽  
Bee-Leng Tan ◽  
Zheng Ling ◽  
...  
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Medial Gastrocnemius ◽  
Myosin Heavy Chain Isoform
Sign in / Sign up

Export Citation Format

Share Document