Journal article
Deletion of 1–43 amino acids in cardiac myosin essential light chain blunts length dependency of Ca2+ sensitivity and cross-bridge detachment kinetics
American journal of physiology. Heart and circulatory physiology, Vol.304(2), pp.H253-H259
01/15/2013
Handle:
https://hdl.handle.net/2376/104459
PMCID: PMC3543674
PMID: 23144314
Abstract
The role of cardiac myosin essential light chain (ELC) in the sarcomere length (SL) dependency of myofilament contractility is unknown. Therefore, mechanical and dynamic contractile properties were measured at SL 1.9 and 2.2 μm in cardiac muscle fibers from two groups of transgenic (Tg) mice:
1
) Tg-wild-type (WT) mice that expressed WT human ventricular ELC and
2
) Tg-Δ43 mice that expressed a mutant ELC lacking 1–43 amino acids. In agreement with previous studies, Ca
2+
-activated maximal tension decreased significantly in Tg-Δ43 fibers. pCa
50
(−log
10
[Ca
2+
]
free
required for half maximal activation) values at SL of 1.9 μm were 5.64 ± 0.02 and 5.70 ± 0.02 in Tg-WT and Tg-Δ43 fibers, respectively. pCa
50
values at SL of 2.2 μm were 5.70 ± 0.01 and 5.71 ± 0.01 in Tg-WT and Tg-Δ43 fibers, respectively. The SL-mediated increase in the pCa
50
value was statistically significant only in Tg-WT fibers (
P
< 0.01), indicating that the SL dependency of myofilament Ca
2+
sensitivity was blunted in Tg-Δ43 fibers. The SL dependency of cross-bridge (XB) detachment kinetics was also blunted in Tg-Δ43 fibers because the decrease in XB detachment kinetics was significant (
P
< 0.001) only at SL 1.9 μm. Thus the increased XB dwell time at the short SL augments Ca
2+
sensitivity at short SL and thus blunts SL-mediated increase in myofilament Ca
2+
sensitivity. Our data suggest that the NH
2
-terminal extension of cardiac ELC not only augments the amplitude of force generation, but it also may play a role in mediating the SL dependency of XB detachment kinetics and myofilament Ca
2+
sensitivity.
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Details
- Title
- Deletion of 1–43 amino acids in cardiac myosin essential light chain blunts length dependency of Ca2+ sensitivity and cross-bridge detachment kinetics
- Creators
- John Jeshurun Michael - Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, Washington State University, Pullman, Washington; andSampath K Gollapudi - Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, Washington State University, Pullman, Washington; andSteven J Ford - Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, Washington State University, Pullman, Washington; andKatarzyna Kazmierczak - Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FloridaDanuta Szczesna-Cordary - Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FloridaMurali Chandra - Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, Washington State University, Pullman, Washington; and
- Publication Details
- American journal of physiology. Heart and circulatory physiology, Vol.304(2), pp.H253-H259
- Academic Unit
- Integrative Physiology and Neuroscience, Department of
- Publisher
- American Physiological Society; Bethesda, MD
- Identifiers
- 99900546952001842
- Language
- English
- Resource Type
- Journal article