Publisher's Synopsis
Calcium Waves, Gradients and Oscillations Chairman: Michael J. Berridge 1995 Standing free gradients are widespread in living systems and changes in intracellular free Ca2+ concentration, [Ca2+]i, are involved in controlling the responses of cells to many stimuli. Imaging techniques have revealed complex patterns of Ca2+ distribution arising spontaneously or after stimulation of cells by hormones or neurotransmitters. In many cells, Ca2+- mobilizing agonists stimulate oscillations in [Ca2+]i, with the frequency of the concentration rises ( spikes') depending on the agonist concentration and the external Ca2+ concentration. The Ca2+ spikes are organized spatially as well as temporally, so that a regenerative wave spreads across the cell. Such Ca2+ waves have been observed in many cell types: in hamster eggs, fertilization stimulates a Ca2+ wave that spreads from the point of sperm entry to the opposite pole; in Xenopus oocytes, the Ca2+ signal is initiated at several foci, with the waves spreading out symmetrically to give spheres or asymmetrically to give spirals.;Most of the models proposed to explain the initiation and propagation of Ca2+ waves involve positive feedback, with Ca2+ amplifying its own release through an action on phospholipase C, generating periodic surges of inositol 1,4,5-trisphosphate (InsP3), or through Ca2+- induced Ca2+ release. Propagation seems to depend on the regenerative release of Ca2+ from internal stores controlled by the InsP3 receptor or the ryanodine receptor. This book features studies of intracellular Ca2+ gradients, oscillations and waves in various systems. Calcium gradients are best understood in tip-growing plants cells, medaka (fish) eggs and the mould Dictyostelium. Current knowledge of the initiation, propagation, characteristics, functional consequences and physiological significance of Ca2+ oscillations and waves in heptocytes, in Cl- secretion from pancreatic acinar cells, in heart muscle cells and in neurons is presented. The mechanisms, form and importance of Ca2+ waves in Xenopus oocytes and in mammalian fertilization are considered.;The biochemical basis of Ca2+ signals can spread as waves from cell to cell, through the action of a secreted intermediate (ATP) or by diffusion of InsP3 or perhaps Ca2+, across gap junctions; studies of this process in epithelial cells and glial cells are featured. Related Ciba Foundation Symposia: No. 183 Circadian clocks and their adjustment Chairman: J. M. Waterhouse 1995 ISBN 0 471 94305 3 No. 164 Interactions among cell signalling systems Chairman: Y. Nishizuka 1992 ISBN 0 471 93073 3
