Effect of 2-4-dinitrophenol on intercellular communication in mammalian cardiac fibres

The effect of 2-4-dinitrophenol (DNP) on cell communication, in canine Purkinje fibres, was investigated. It was found that DNP (0.5 MM) suppressed the electrical coupling in about 10 min. This effect of DNP was largely due to an increment in intracellular longitudinal resistance. The longitudinal movement of fluorescein (mol. wt. 320) along Purkinje strands, followed with the cut-end method, was also suppressed by DNP (0.5 mM). The decoupling action of DNP was related to release of Ca from intracellular stores and increase in free (Ca)i. The intracellular injection of EDTA reestablished the electrical coupling of Purkinje cells previously uncoupled by DNP. The results described in this paper indicate that cell communication in heart fibres is greatly dependent on the synthesis of high energy phosphate bonds.