This volume is one of those published from the proceedings of the invited lectures to the First International Congress of Comparative Physiology and Biochemistry I organized at Liege (Belgium) in August 1984 under the auspices of the Section of Comparative Physiology and Biochemistry of the International Union of Biological Sciences. In a general foreword to these different volumes, it seems to me appropriate to consider briefly what may be the comparative approach. Living organisms, beyond the diversity of their morphological forms, have evolved a widespread range of basic solutions to cope with the different problems, both organismal and environmental with which they are faced. Soon after the turn of the century, some biologists realized that these solutions can be best comprehended in the frame work of a comparative approach integrating results of physiological and biochemical studies done at the organismic, cellular and molecular levels. The development of this approach amongst both physiologists and biochemists remained, however, extremely slow until recently.

After the pioneering studies by Ussing and co-workers, studies of epithelial Nael transport have come a long way. The first phase of the phenomenological description of the cell as a black box has been follow ed by studies of cellular mechanisms, the interplay of the different trans port components, and the mechanisms of regulation. A broad spectrum of methods has been applied to many epithelia in a variety of species. For the individual epithelia transport schemes have been proposed, and, at this point I think it is appropriate to take a pause and search for elements common to several epithelia. This aspect triggered the publica tion of this book, and in fact the various chapters emphasize that the funetional eomponents, expressed in the various epithelia, are not in finite in number, but they occur in epithelia which are separated in evolu tion by several hundred million years. The authors come both from the field of veterinary and human physiology as weIl as from biology. In my opinion, the close contacts and eollaborations between physiologists and biologists have been essential for the progress in this field. I wish to thank all authors for their con tributions, and I hope that the reader will appreciate this collection of up to date reviews on epithelia in nonvertebrates and vertebrates.

Fish Physiology: Physiology of Elasmobranch Fishes, Volume 34B is a useful reference for fish physiologists, biologists, ecologists, and conservation biologists. Following an increase in research on elasmobranchs due to the plight of sharks in today's oceans, this volume compares elasmobranchs to other groups of fish, highlights areas of interest for future research, and offers perspective on future problems. Covering measurements and lab-and-field based studies of large pelagic sharks, this volume is a natural addition to the renowned Fish Physiology series. - Provides needed comprehensive content on the physiology of elasmobranchs - Offers a systems approach between structure and interaction with the environment and internal physiology - Contains contributions by leading experts in their respective fields, under the guidance of internationally recognized and highly respected editors - Highlights areas of interest for future research, including perspective on future problems

Current Topics in Membranes and Transport

Studies on the colon not only serve medical interest or clinical purposes, but are also a highly interesting subject of comparative physiology, from which we can learn much about the basic principles in physiology. Presented here are examples of research on colonic ion transport of each vertebrate group, including the classical models of epithelia, rat and rabbit, and also on the special and unique features in fish, amphibians, reptiles, birds, and selected mammals such as the guinea pig. Physiology and pathophysiology of ion transport in the human large intestine are as well covered as the use of colonic cell cultures as model systems for crypt cell properties.

Biological cell membranes regulate the transfer of matter and informa tion between the intracellular and extracellular compartments as basic survival and maintenance functions for an organism: This volume contains a series of reviews that are concerned with how biological plasma membranes regulate the transport of chloride between the intracellular and extracellular compartments of a cell. This book is also an attempt to analyze the molecular basis for the movement of chloride across a cell membrane. This volume is devoted to a diversity of electrogenic chloride transport mechanisms in representative cell membranes of all living things. The first section of the book (Chaps. 1-4) focuses on mech anisms of primary active chloride transport (i.e. photon or A TP-driven), while the second section (Chaps. 5-6) centers on secondary active chloride transporters (symport and antiport) in both plant and animal plasma membranes. The last section, which comprises seven chapters (Chaps. 7-13), deals with chloride channels in cell membranes of prokaryocytes and eukaryocytes of most every phylum. It is hoped that with this particular ordering the reader can glean a telescopic view of the evolutionary history of the various electrogenic chloride transporters.

The ability to regulate cell volume in the face of osmotic challenge is one of the most fundamental of cellular homeostatic mechanisms. Cellular and Molecular Physiology of Cell Volume Regulation is an integrated collection of articles describing key aspects of cell volume control. The book has been organized around concepts and cellular/molecular processes rather than around mechanisms of volume regulation in specific cell types in order to make it more accessible to a multidisciplinary audience of students, instructors, and researchers.