The crucial role played by calcium as a cellular messenger has become increasingly evident, as has the recognition that cells spend much energy in maintaining the cytosolic concentration of this cation both constant and low. It is thought they do this to avoid precipitating phosphate, needed as a source of bond energy and to modulate protein structure. Moreover, since calcium that does enter the cell must be disposed with, processes that utilize calcium have evolved, e.g. secretion, contraction, signaling, to name just some. New knowledge concerning the processes of cellular calcium entry, extrusion and the fate of intracellular calcium has accumulated in recent years. Much has also been learned about calcium transport by and across epithelial cells. It seems logical to think that the processes of calcium entry, extrusion and intracellular handling are similar in all cells. We have therefore assembled in one volume overviews and research reports of transport and cellular calcium regulation so as to explore similarities and differences between cells that utilize calcium for metabolic purposes and those whose primary function is transport.

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Section I Cellular Calcium Entry - Calcium Channels.- Modulation and functions of Neuronal Ca2+ Permeable Channels.- Control of Calcium Influx and Internal Calcium Release in Electrically Non-Excitable Cells.- Patch Clamp Study of Ca Channels in Isolated Renal Tubule Segments.- Recent Developments in the Molecular Characterization of the L-Type Ca2+-Channel and Mitochondrial Ca2+-Antagonist Sites.- Evidence for an Intracellular Ryanodine and Caffeine-Sensitive Calcium Ion-Conducting Channel in Excitable Tissues.- Characterization of Novel Probes of Voltage-Dependent Calcium Channels.- Section II Calcium Extrusion - The Ca ATPases.- The Calcium Pumping APTase of the Plasma Membrane Structure-Function Relationships.- Tertiary Structure of the Muscle Calcium Pump.- A 19kD C-Terminal Tryptic Fragment of the Alpha Chain of Na/K-ATPase, essential for Cation Occlusion and Transport.- The Activity of the Basolateral Membrane Calcium-Pumping ATPase and Intestinal Calcium Transport.- Section III Calcium Extrusion - The Na/Ca Exchanger.- Sodium-Calcium Exchange in the Heart.- The Role of Sodium/Calcium Exchange in the Regulation of Vascular Contractility.- Section IV Regulation And Regulatory Role Of Intracellular Calcium.- Function and Regulation of Intracellullar Ca in Renal Cells.- Na+-Ca2+ and Na+-H+ Antiporter Interactions Relations Between Cytosolic Free Ca2+, Na+ and Intracellular pH.- Regulation of Intracellular Calcium in Cultured Renal Epithelioid (MDCK-) Cells.- Assessment of the Role of Calcium in Neutrophil Activation Using Electropermeabilized Cells.- The Role of Calcium in Regulating the Agonist-Evoked Intracelllular Acidosis in Rabbit Salivary Gland Acini.- Free Calcium in Red Blood Cells of Human Hypertensives is Elevated: How Can This Be ?.- Section V Epithelial Calcium Transport.- Transepithelial Calcium Transport in Gut and Kidney.- Intestinal Calcium Absorption: The Calbindins, The Visualization of Transported Calcium and a New Rapid Action of 1,25-Dihydroxyvitamin D3.- Intestinal Calcium Transport: Vesicular Carriers, Noncytoplasmic Calbindin D 28K, and Non-Nuclear Effects of 1,25-Dihydroxyvitamin D3.- Calcium Transport Across the Colon.- Calcium Absorption. Vitamin D Effects on Rat Intestinal Calcium Transport Systems Depend on the State of Enterocyte Differentiation Along the Crypt-Villus Axis.- Oscillations on Intestinal Calcium Absorption as Observed and as Predicted by Computer Simulation.- Mechanisms and Sites of Transepithelial Ca2+ Transport in Kidney Cells.- Mechanisms of H+/HCO3 Transport in Rat Kidney Medullary Thick Ascending Limb. Effects of Arginine Vasopressin.- Section VI Calcium-Binding Proteins Characteristics and Structure.- Structure and Selectivity of Ca-binding Sites in Proteins: The 5-Fold Site in an Icosahedral Virus.- Molecular and Functional Aspects of Some Cytosolic Calcium-Binding Proteins.- The Major Protein of Frog Otoconia is a Homolog of Phospholipase A2.- Phosphorylase Kinase from bovine Stomach Smooth Muscle: A Ca2+-Dependent Protein Kinase Associated with an Actin-Like Molecule.- Section VII The Calbindins - Gene Structure And Function.- Structure and Functional Analysis of the Chick Calbindin Gene.- Regulation of Calbindin-D28k Gene Expression.- Structure and Regulation of the Rat Duodenal Calbindin-D9k (CaBP-9K) Gene.- Comparative Regulation at the Intestinal and Uterine Level of Calbindin mRNA in the Fowl.- Calbindin-D9k Localization and Gestational Changes in the Utero-Placental Unit: A Model for Maternal-Fetal Calcium Transports.- Potential Role of Calbindins in Enamel Calcification.- Section VIII Defects of Calcium Transport.- Intestinal Calcium Transport and Bone Mineralization in the Spontaneously Diabetic BB Rat.- Calcium Transport in the Streptozotocin Diabetic Rat : Studies with Brush Border Membrane Vesicles.- Epithelial Calcium Transport in the Spontaneously Hypertensive Rat (SHR).- Interaction Between Calcitriol and Thyroid Hormone: Effects on Intestinal Calcium Transport and Bone Resorption.- Lead Poisoning and Calcium Transport.- Tumoral Parathyroid Hormone-Related Protein and Calcium Transport.- Section IX In Recognition.- Felix Bronner-Forty Years Devoted to Calcium Homeostasis and Transport.