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Ca2+-sensing transgenic mice: postsynaptic signaling in smooth muscle
Guangju Ji1, Morris E Feldman, Ke-Yu Deng
1Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
The Journal of Biological Chemistry
|March 3, 2004
Summary
Researchers developed a transgenic mouse using G-CaMP to visualize calcium signaling in smooth muscle. This revealed two distinct postsynaptic calcium signals: rapid "calcium flashes" and slower "calcium waves," offering new insights into cellular communication.
Area of Science:
- Physiology
- Molecular Biology
- Genetics
Background:
- Genetically encoded signaling proteins enable in vivo monitoring of cellular events.
- Understanding postsynaptic signaling in smooth muscle is crucial for physiological studies.
Purpose of the Study:
- To develop a transgenic mouse model for studying postsynaptic signaling in smooth muscle.
- To utilize a genetically encoded calcium indicator (G-CaMP) for real-time calcium dynamics.
- To differentiate and characterize distinct postsynaptic calcium signals in smooth muscle.
Main Methods:
- Development of a transgenic mouse expressing circularly permutated, calcium-sensing G-CaMP.
- Expression of G-CaMP in vascular and non-vascular smooth muscle.
- Analysis of postsynaptic calcium signals in detrusor smooth muscle tissue using intrinsic nerve stimulation.
Main Results:
- Identified two distinct postsynaptic calcium signals: rapid 'calcium flashes' and slow 'calcium waves'.
- Calcium flashes mediated by P2X receptors and ryanodine receptor-mediated calcium release.
- Calcium waves mediated by muscarinic receptors and inositol trisphosphate-mediated calcium release.
- Demonstrated that individual myocytes can exhibit both responses, with a transition at higher synaptic inputs.
Conclusions:
- The developed G-CaMP transgenic mouse serves as a valuable tool for studying smooth muscle physiology.
- Distinct ionotropic and metabotropic postsynaptic calcium signaling pathways were elucidated.
- These findings advance the understanding of processive biological signaling in smooth muscle.