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Contractility and myosin heavy chain isoform patterns in developing tracheal muscle
D A Roepke1, S L Griffith, R A Meiss
1Department of Physiology and Biophysics, Indiana University School of Medicine, Indianapolis 46202-5120.
Respiration Physiology
|September 1, 1994
Summary
Post-neonatal development does not alter rabbit airway smooth muscle contractility or myosin heavy chain (MHC) isoforms. Changes in airway reactivity are likely due to receptor or second messenger system modifications.
Area of Science:
- Physiology
- Developmental Biology
- Smooth Muscle Research
Background:
- Airway smooth muscle (ASM) reactivity changes with development.
- These changes may stem from alterations in excitation-contraction coupling or the contractile apparatus.
Purpose of the Study:
- To investigate the mechanisms behind developmental changes in airway smooth muscle reactivity.
- To examine ASM contractility and myosin heavy chain (MHC) isoform patterns during post-neonatal development in rabbits.
Main Methods:
- Tracheal smooth muscle (TSM) strips from 8- and 25-week-old male rabbits were used.
- Length-tension and force-velocity curves were measured under electrical stimulation.
- Myosin heavy chain (MHC) isoform ratios were analyzed using SDS-PAGE.
Main Results:
- No significant differences were found in passive or active length-tension curves or force-velocity curves between the age groups.
- Myosin heavy chain (MHC) isoform ratios in rabbit TSM remained unchanged with development.
- This contrasts with findings in porcine trachealis, which show MHC isoform shifts.
Conclusions:
- Rabbit tracheal smooth muscle contractility and MHC isoform patterns do not change during post-neonatal development.
- Developmental changes in airway muscle reactivity are unlikely to be caused by alterations in the contractile apparatus.
- Observed changes in airway reactivity are more likely attributable to modifications in receptors or second messenger systems.