Cell-to-Cell diffusion of Procion Yellow in sheep and calf Purkinje fibers

Summary Sheep and calf Purkinje fibers (false tendons) were cut near one end and exposed to a solution containing no calcium and the dye Procion Yellow (M4RS, molecular weight near 700). Fifteen minutes later the damaged end was sealed by applying calcium ions (Tyrode solution). Traces of Procion Yellow were detected within the intracellular compartment at a distance of 2.4 mm from the site of damage when the preparations had been washed in dye-free solution for 4 hr. This indicates that the dye had diffused through about 20 cells in succession. There was no detectable uptake of Procion Yellow through intact surface membranes. Visual curve fitting to quantitative data on concentrationvs. distance gives an apparent diffusion coefficient (cell junctions and myoplasm in series) of 3×10^–8 cm² sec^–1, as against 1×10^–6 cm² sec^–1 in an agar gel. It is concluded that specialized contact areas between neighboring cardiac cells represent a considerable yet not an absolute hindrance to the movement of this particle.