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Time-of-day effects on ex vivo muscle contractility following short-term satellite cell ablation
Kahn, Ryan E. Lieber, Richard L. Meza, Guadalupe Dinnunhan, Fawzan Lacham-Kaplan, Orly Dayanidhi, Sudarshan Hawley, John A.
Kahn, Ryan E.
Lieber, Richard L.
Meza, Guadalupe
Dinnunhan, Fawzan
Lacham-Kaplan, Orly
Dayanidhi, Sudarshan
Hawley, John A.
Abstract
Muscle isometric torque fluctuates according to time-of-day with such variation owed to the influence of circadian molecular clock genes. Satellite cells (SCs), the muscle stem cell population, also express molecular clock genes with several contractile-related genes oscillating in a diurnal pattern. Currently, limited evidence exists regarding the relationship between SCs and contractility, although long-term SC ablation alters muscle contractile function. Whether there are acute alterations in contractility following SC ablation and with respect to the time-of-day is unknown. We investigated whether short-term SC ablation affected contractile function at two times of day and whether any such alterations led to different extents of eccentric contraction-induced injury. Using an established mouse model to deplete SCs, we characterized muscle clock gene expression and ex vivo contractility at two times-of-day (morning: 0700 and afternoon: 1500). Morning-SC+ animals demonstrated ∼25%–30% reductions in tetanic/eccentric specific forces and, after eccentric injury, exhibited ∼30% less force-loss and ∼50% less dystrophinnegative fibers versus SC− counterparts; no differences were noted between Afternoon groups (Morning-SC+: −5.63 ± 0.61, Morning-SC−: −7.93 ± 0.61; N/cm2; P < 0.05) (Morning-SC+: 32 ± 2.1, Morning-SC−: 64 ± 10.2; dystrophinnegative fibers; P < 0.05). As Ca++ kinetics underpin force generation, we also evaluated caffeine-induced contracture force as an indirect marker of Ca++ availability and found similar force reductions in Morning-SC+ vs. SC− mice. We conclude that force production is reduced in the presence of SCs in the morning but not in the afternoon, suggesting that SCs may have a time-of-day influence over contractile function.
Keywords
contractile injury, contractility, eccentric contractions, molecular clocks, muscle stem cells
Date
2024
Type
Journal article
Journal
American Journal of Physiology: Cell Physiology
Book
Volume
327
Issue
1
Page Range
C213-C219
Article Number
ACU Department
Mary MacKillop Institute for Health Research
Faculty of Health Sciences
Faculty of Health Sciences
Collections
Relation URI
Source URL
Event URL
Open Access Status
License
All rights reserved
File Access
Controlled
Notes
Published by the American Physiological Society.