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The possible role of the intercellular junctions on the sealing process of toad myocardium was investigated in preparations immersed in hypertonic sucrose solutions and in solutions containing EDTA, both of which caused the separation of many intercalated disks and of a large number of cells. The rate of healing was determined by measuring the amplitude of the injury potentials as a function of time. The potential differences were recorded with the "roving" electrode technique immediately after injury and then at 2-minute intervals. Measurements made in preparations immersed in normal Ringer's solution showed that the depolarization caused by a lesion was totally reversed in 10 to 12 minutes. In muscles immersed in hypertonic sucrose solutions for 20 minutes, a marked reduction of the rate of healing was observed. Similar results were obtained with EDTA (2.5 mM) or with Ca 2+ -free solutions. The effect of hypertonic solutions was not counteracted by the addition of 10 mM Ca 2+ to the solution. The results suggest that the integrity of the intercellular junctions is essential for the healing process.
Mello et al. (Sat,) studied this question.