This book provides a detailed account of the intricate mechanisms and regulation of epithelial chloride transport, offering valuable insights into the regulation of salt balance in various vertebrate epithelial tissues. Over sixty years ago, J. Wendell Burger discovered that the rectal gland of elasmobranchs was the extrarenal organ responsible for excreting the salt gained by the animals. Since then, the rectal gland of elasmobranchs has been the only organ enabling whole organ, tissue, cellular and molecular studies of secondary active transport.

The rectal gland has not only illuminated the mechanism of chloride transport, but also allowed the characterization of some of the proteins involved in transport. The NaK-ATPase was first isolated and purified, and its biochemical properties were linked to transport activities. The sodium-potassium-two chloride cotransporter NKCC1 was cloned from this gland. Understanding chloride transport, as revealed through experiments on this gland, has provided insight into the physiology and pathophysiology of chloride transport disorders.

Readers will gain an insight into the scientists, protocols and specific experiments involved in nearly a century of research into the elasmobranch rectal gland, shedding light on the complex mechanisms and regulation of epithelial chloride transport.

Patricio Silva, M.D. is a Nephrologist that graduated from Medical School in 1964, did a residency in Internal Medicine at The Clinical Hospital of the University of Chile after which he briefly joined the faculty. He did a Nephrology Fellowship at Yale and has been an Academic Nephrologist initially at the School of Medicine of Yale University, then at Harvard Medical School and its associated hospitals first The Boston City, then the Beth Israel, and lastly the Deaconess Hospitals, after which he moved to Temple University in Philadelphia, Pennsylvania, from where he retired as Emeritus Professor. He also did research at the Max-Plank-Institute für Biophysik in Frankfurt am Main, Germany, and the Department of Biochemistry at Harvard University, Cambridge, Massachusetts. Throughout his career he was a Principal Investigator and Adjunct Professor at The Mount Desert Island Biological Laboratory for more than fifty years and where he continues to work on the physiology and molecular biology of the transport of chloride by the rectal gland of the shark. He is the author of more than three hundred publications in peer reviewed journals and the Bulletin of the Mount Desert Island Biological Laboratory, a significant proportion of them on the biochemistry, physiology and molecular biology of the transport of chloride.