FREEZE-INDUCED SHRINKAGE OF INDIVIDUAL CELLS AND CELL-TO-CELL PROPAGATION OF INTRACELLULAR ICE IN CELL CHAINS FROM SALIVARY-GLANDS

The formation of intracellular ice (IIF), usually a lethal event to he avoided when cryopreserving cells, should, however, be enforced durin g the cryosurgical destruction of tumour cells. IIF has been investiga ted so far only in single cells in suspension. Because cells in tissue s cannot be successfully cryopreserved, in contrast to single cells in suspension, the mechanism of IIF in tissues may depend on factors tha t facilitate IIF. We studied IIF in cell strands from salivary glands, which represent a simple form of a tissue. Their cells are connected by channels responsible for intercellular communication. A substantial fraction of cell dehydration during freezing occurs before cells are encapsulated by ice, and the degree of this pre-ice-front shrinkage ap pears to influence IIF. In strands with coupled cells IIF spread from one cell to adjacent cells in a sequential manner with short delays (2 00-300 ms), suggesting cell-to-cell propagation via intercellular chan nels. In strands pretreated with decoupling agents (dinitrophenol, hep tanol), sequential IIF was absent. Instead, formation of ice was rando m, with longer and variable delays between consecutive darkenings indi cating IIF. Results suggest that the mechanism of IIF spread, and cons equently the degree of cryodamage in tissue, can be influenced by the presence of intercellular channels (gap junctions).