Journal
JOURNAL OF APPLIED PHYSIOLOGY
Volume 90, Issue 1, Pages 380-388Publisher
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/jappl.2001.90.1.380
Keywords
postnatal development; maximum specific force; myosin heavy chain content; force per cross bridge; single fibers
Categories
Funding
- NATIONAL HEART, LUNG, AND BLOOD INSTITUTE [R01HL034817, R01HL037680] Funding Source: NIH RePORTER
- NHLBI NIH HHS [HL-34817, HL-37680] Funding Source: Medline
Ask authors/readers for more resources
It has been found that maximum specific force (F(max); force per cross-sectional area) of rat diaphragm muscle doubles from birth to 84 days (adult). We hypothesize that this developmental change in F(max) reflects an increase in myosin heavy chain (MHC) content per half-sarcomere (an estimate of the number of cross bridges in parallel) and/or a greater force per cross bridge in fibers expressing fast MHC isoforms compared with slow and neonatal MHC isoforms (MHC(slow) and MHC(neo), respectively). Single Triton 100-X-permeabilized fibers were activated at a pCa of 4.0. MHC isoform expression was determined by SDS-PAGE. MHC content per half-sarcomere was determined by densitometric analysis and comparison to a standard curve of known MHC concentrations. MHC content per half-sarcomere progressively increased during early postnatal development. When normalized for MHC content per half-sarcomere, fibers expressing MHC(slow) and coexpressing MHC(neo) produced less force than fibers expressing fast MHC isoforms. We conclude that lower force per cross bridge in fibers expressing MHC(slow) and MHC(neo) contributes to the lower F(max) seen in early postnatal development.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available