Ultradian rhythms in cell population. Problem of synchronization

Abstract

The studies demonstrating cooperativity of cells in synchronization of their activity are reviewed. The total ultradian rhythm in a cell culture is taken as a marker of synchronization. Self-synchronization of interacting oscillators has been demonstrated in experiments. Special attention is paid to the mechanisms underlying formation of ultradian rhythms of protein synthesis in a culture of rat hepatocytes. Formation of populational rhythm in these cells is a function of cell density and time of culturing without replacing growth medium (conditioning). The addition of some individual exogenous gangliosides to the culture medium simulates the effects of conditioning. [mmunocytochemical studies showed that intmcellular expression of ganglioside determinants is eiflaanced during the conditioning of culture medium. Exchange of gangliosides between cells and their intracellular accumulation may be the first step in synchronization of cell activity. Synchronization of the protein synthesis oscillations was demonstrated in hepatocytes in situ in a denervated liver.From these observations and literature data it is concluded that self-synchronization of cellular activity is a fundamental regulatory mechanism of organ functioning which operates in line with regulatory systems acting at the organism level.