Main description:

An enormous amount of research effort has been directed toward elucidating the mechanism by which substances are extruded from cells; and reviews have been written and symposia held in order to systematize the plethora of evidence made available. However, the approaches employed to study the secretory process have been so diverse that it is difficult, if not impossible, for one individual or even a group of individuals to keep abreast of all aspects of the field and to analyze them critically. Thus I undertook the writing of this volume with a great deal of trepidation. In searching for some starting point, I naturally considered as my primary focus the role of calcium in the secretory process, which has occupied my research interests for the past 13 years. But since so much experimentation has been carried out on this and related topics during the last decade or two, I felt it was still necessary to visualize this venture from two alternative ap proaches: (1) a more general one, which would cover the subject of calcium and the secretory process from a broad perspective, but of course not in great detail, and (2) a more specific one, restricting coverage to carefully defined limits but with comprehensive analysis of limited topics. The final course undertaken appears to lie somewhere between these two extremes.

Contents:

1 General Concepts.- Biological Importance of Calcium.- Calcium Distribution and Tissue Concentrations.- Redistribution of Calcium during Stimulation.- Regulation of Cell Calcium.- Binding.- Exchange Diffusion.- Active Transport.- Calcium and Membrane Permeability.- Ion Antagonisms.- Summary and Conclusions.- 2 Action of Calcium on the Secretory Process.- Cholinergic Neurons, Chromaffin Cells, and Neurosecretory Cells.- Historical Background.- Electrophysiological Events Associated with Secretion.- Role of Monovalent Cations.- Multivalent Cations.- Conclusions.- Other Neuronal Systems.- Excitatory and Inhibitory Synapses.- Adrenergic Synapses.- Release of Other Biogenic Amines.- Histamine.- 5-Hydroxytryptamine.- Release of Water and Protein.- Salivary Gland.- Exocrine Pancreas.- Granular Proteins from Leukocytes.- Gastric Secretion.- Endocrine Secretory Systems.- Insulin Release.- Corticosteroids.- Thyroid Hormone..- Pituitary Trophic Hormones.- Parathyroid Hormone and Calcitonin.- Conclusions.- 3 Nature of the Role of Calcium in Secretion.- Mechanism of Secretion.- Mode of Calcium Action.- Physical Theories.- Chemical Theories.- Microtubular-Microfilamentous System.- Cytoplasmic Motility.- Conclusions.- 4 Role of Cyclic AMP in the Secretory Process.- Effects of Exogenous Cyclic Nucleotide.- Phosphodiesterase Inhibition.- Measurement of Cyclic AMP Levels.- Interaction between Calcium and Cyclic AMP.- Prostaglandins.- Conclusions.- References.