Ion Channels and Ion Pumps

Omnis cellula e cellula, "every cell from a cell," was dogma to the 19th century cellular physiologist and the cornerstone of Virchow's Cellular pathologie. "Spread out a cell into a layer and you will find that, in ceasing to be a cell, it has ceased to act as such," wrote the British 1 physiologist G . R. Lewes more than a century age. "The cell remains vital as long as its wall remains intact . . . " keeping its content "pure and clear" and thus preserving the "vital principle" within, echoed Claude 2 Bernard a few years later. The notion of the cell membrane as a pro tecting envelope held sway until it became clear that it could not account for the "coalescence" of poorly differentiated embryonic "vesicles" and for their transformation into "cell-like structures" capable of auto regulation and yet subject to what the grandfather of one of us defined as the "federal obligations imposed by the whole organism. ,,3 A new concept was needed, and soon the membrane was described as a structure capable of uniting as well as separating adjacent cells. Morphologic evidence for this dual function was obtained several years later when the electron microscope revealed the existence of tight and gap junc tions which, acting as intercellular bonds and channels, allowed the cells to communicate with one another and thus coordinate their biologic activities.

Omnis cellula e cellula, "every cell from a cell," was dogma to the 19th century cellular physiologist and the cornerstone of Virchow's Cellular pathologie. "Spread out a cell into a layer and you will find that, in ceasing to be a cell, it has ceased to act as such," wrote the British 1 physiologist G .

Preface.- Contributors.- 1. The Molecular Structure and Gating of Calcium Channels.- 2. Calcium Signals in Cell Proliferation, Differentiation, and Death.- 3. Role of Calcium in Stimulus-Secretion Coupling in Exocrine Glands.- 4. Calcium Channels, the Pancreatic Islet, and Endocrine Secretion.- 5. Calcium Channels in Cells of the Anterior Pituitary.- 6. Role of Calcium in the Secretion of Atrial Natriuretic Peptide.- 7. Intracellular Ca2+ and Insulin Action: Possible Role in the Pathogenesis of Syndrome X.- 8. [Ca2+]i and Contraction of Arterial Smooth Muscle.- 9. Autoimmunity Against the Nicotinic Acetylcholine Receptor and the Presynaptic Calcium Channel at the Neuromuscular Junction.- 10. Clinical Pharmacology of Calcium Channels.- 11. Hormonal Modulation of Sodium Pump Activity: Identification of Second Messengers.- 12. Endogenous Regulation of Sodium Pump Activity.- 13. Structure, Gating, and Clinical Implications of the Potassium Channel.- 14. Potassium Channels in Skeletal Muscle.- 15. The Role of Potassium Ions in the Control of Heart Function.- 16. Nonrenal Potassium Homeostasis: Hypokalemia and Potassium Depletion - Role of Skeletal Muscle Potassium-Pump (Na+,K+ -ATPase).- 17. The Clinical Pharmacology of Potassium Channels.- 18. Ion Transport in Vascular Smooth Muscle and the Pathogenesis of Hypertension.- 19. Calcium Ion Homeostasis in the Aging Brain: Regulation of Voltage-Dependent Calcium Channels.- 20. Interactions of Ethanol with Ion Channels: Possible Implications for Mechanisms of Intoxication and Dependence.- 21. Structure and Function of Receptor-Mediated Chloride Channels in the Central Nervous System.- 22. Characterization of Ion Channels in the Central Nervous System: Insights from Radioligand Binding, Autoradiography, and In Situ Hybridization Histochemistry.- 23. Chloride Channels in Cystic Fibrosis.- 24. Cyclic Nucleotide-Activated Channels.- 25. Transport Systems for Arsenic, Antimony, and Cadmium Ions Encoded by Bacterial Plasmids.