The role of calcium in the cold shock responses

Brief cold shock induces several physiological responses in corn root tissue. Ion fluxes across the membrane are greatly affected and cold shock application leads to a rapid influx of calcium towards the cytosol. Given the second messenger role claimed for this ion in the transduction of environmental and hormonal signals in the living cells, we have studied the effect of Ca2+-channel blockers during the response to cold shock. Ca2+ influx was inhibited or reduced demonstrating that its influx was not simply due to an increased membrane permeability but rather to the opening of Ca2+ channels which, under the conditions of a highly favourable electrochemical gradient, permitted its passive entrance into the cytosol. Other parameters are also influenced by the application of these compounds, showing a cause-effect linkage to the increased cytosolic Ca2+ concentration. In fact, potassium efflux is greatly diminished and there is also a decrease in the hydrolysis of membrane phospholipids. A tentative model to explain how calcium might be implicated in the physiological responses to cold shock is discussed.