Fluorescence Recovery After Photobleaching
As was first demonstrated by the cell-to-cell spread of a fluorescent diffusion tracer introduced into one cell by microinjection (1), the permeability of the gap junctions is not restricted to the small intracellular electrolytes that carry the junctional currents. Quantitative data on the permeability of gap junctions for larger solutes, which include second messengers and other signaling molecules, contribute to the understanding of their function. The microinjection method (see Chapter 12) provides information on the presence of functional gap junctions and on the size of the permeating molecules, but permeability coefficients have usually not been obtained with this technique. Indeed, for reasons related to the complex geometry of the diffusion system from one progressively microinjected cell toward a variable number of adjacent and remote cells, long and difficult calculations are involved even in the most simple case of one-dimensional diffusion (2).
KeywordsPermeability Hydrolysis Ischemia DMSO CaCl2
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