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Bladder Smooth Muscle Strip Contractility as a Method to Evaluate Lower Urinary Tract Pharmacology
Published on: August 18, 2014
Smooth muscle myosin heavy chains are developmentally regulated in the rabbit bladder
V K Lin1, J B Robertson, I L Lee
1Department of Urology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390-9110, USA.
The Journal of Urology
|September 19, 2000
Summary
Smooth muscle myosin heavy chain (MHC) isoform expression, SM1 and SM2, is developmentally regulated in rabbit bladders. This shift, occurring at the mRNA level, parallels changes in SM cell growth and tissue development.
Area of Science:
- Biochemistry
- Developmental Biology
- Smooth Muscle Physiology
Background:
- Smooth muscle (SM) myosin heavy chain (MHC) exists as SM1 and SM2 isoforms, produced via alternative splicing from a single gene.
- While functional differences remain unclear, altered SM1/SM2 ratios are implicated in various pathophysiological conditions.
Purpose of the Study:
- To investigate the developmental regulation of SM1 and SM2 MHC isoform expression in rabbit bladder detrusor smooth muscle.
- To determine if changes in the SM1/SM2 ratio occur during postnatal development.
Main Methods:
- Analysis of SM MHC isoform expression at both protein and mRNA levels in rabbit bladders across different developmental stages (fetal to adult).
- Techniques included porous SDS-PAGE, S1 protection assay, and histological analysis.
Main Results:
- SM1 was the predominant MHC isoform in fetal and neonatal bladders.
- The SM1/SM2 ratio significantly decreased postnatally, shifting from SM1 dominance to SM2 dominance in adult rabbits.
- Developmental changes in MHC protein isoforms closely mirrored those of their corresponding mRNAs, with SM2 mRNA becoming predominant after birth.
Conclusions:
- Smooth muscle MHC expression in the detrusor is developmentally regulated, likely at the mRNA level.
- The observed shift in MHC isoforms correlates with SM cell growth and the resolution of primitive mesenchyme in the developing bladder.
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