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Developmental aspects of bladder contractile function: evidence for an intracellular calcium pool
S A Zderic1, U Sillen, G H Liu
1Urology Research Laboratories, Children's Hospital of Philadelphia, Pennsylvania.
The Journal of Urology
|August 1, 1993
Summary
Neonatal bladder smooth muscle shows lower calcium sensitivity compared to mature muscle, suggesting developmental changes in intracellular calcium handling. This indicates maturation increases calcium binding and release in bladder smooth muscle.
Area of Science:
- Physiology
- Developmental Biology
- Smooth Muscle Research
Background:
- Functional changes in smooth muscle during development are linked to intracellular calcium content.
- Neonatal bladder smooth muscle may exhibit altered calcium permeability.
Purpose of the Study:
- To investigate potential differences in calcium handling between neonatal and mature rabbit bladder smooth muscle.
- To test the hypothesis that neonatal bladder smooth muscle has altered calcium permeability and sensitivity.
Main Methods:
- Utilized the radioligand H3 PN-200 for Scatchard analyses to assess calcium receptor density and dissociation constants.
- Measured calcium sensitivity in isolated bladder smooth muscle strips via dose-response curves after calcium depletion and repletion.
Main Results:
- No significant differences in calcium receptor density or dissociation constants were found between neonatal and mature bladder smooth muscle.
- Neonatal bladder smooth muscle strips demonstrated significantly lower effective calcium dose for 50% maximal response compared to mature strips (1.5 mM vs. 7.5 mM).
Conclusions:
- Findings support the hypothesis of lower intracellular calcium binding and secondary release in neonatal bladder smooth muscle, which increases with maturation.
- These results align with observed maturational increases in intracellular calcium binding and storage in developing myocardium.