Related Experiment Videos
Two-dimensional coupling by gap junctions in cultured gastric smooth muscle monolayers
D M Larson1, R J Gilbert, E C Beyer
1Mallory Institute of Pathology, Boston University School of Medicine 02118.
The American Journal of Physiology
|August 1, 1992
Summary
Gastric smooth muscle cells exhibit anisotropic electrotonic current flow primarily due to cell shape, not membrane properties. Normalizing cell shape to hexagons eliminated this anisotropy, revealing uniform gap junction coupling.
Area of Science:
- Cellular biology
- Physiology
- Biophysics
Background:
- Cultured rabbit gastric smooth muscle cells form parallel, spindle-shaped arrays in vitro.
- Understanding intercellular communication in these monolayers is crucial for physiological studies.
Purpose of the Study:
- To investigate the role of cell shape and orientation in two-dimensional electrotonic coupling.
- To determine the primary drivers of anisotropic current flow in gastric smooth muscle cell monolayers.
Main Methods:
- Microinjection of Lucifer yellow dye and electrotonic current.
- Electron microscopy to identify gap junctions.
- Northern blot analysis for connexin43 mRNA expression.
- Electrophysiological recordings with two intracellular microelectrodes.
- Modified two-dimensional modeling of current flow.
Main Results:
- High dye transfer (97%) to adjacent cells confirmed gap junction communication.
- Connexin43 mRNA was detected, indicating functional gap junctions.
- Initial analysis showed anisotropic current flow (space constant ratio 4.4).
- Geometric normalization of cell shape to hexagons resulted in equivalent space constants (200-256 microns).
Conclusions:
- Anisotropy in gastric smooth muscle cell monolayers is mainly attributed to cell shape.
- Cellular geometry, rather than intrinsic membrane properties or gap junction distribution, dictates anisotropic coupling.
- These findings are vital for interpreting electrophysiological data in smooth muscle tissues.