Regulation of gap junctional channels.

Regulation of gap junctional channels by voltage, calcium, pH and cyclic nucleotides is discussed, with emphasis on the physiological significance of each regulatory mechanism. The range of calcium and hydrogen ion concentrations that shut the junctional channels makes it unlikely that these ions may act as physiological modulators of intercellular communication. On the other hand, voltage and cyclic nucleotides in particular seem to play a physiologically significant role in the modulation of intercellular communication by way of gap junctions.