Foreword

The third Colloque Biomembranes on "Water Epithelial Transport: Mechanisms of Action of Antidiuretic Hormone" was held in Paris from May 15th to 17th 1988. It was sponsored by the French Commissariat/~ l'Energie Atomique, by the Institut National de la Sant~ et de la Recherche M6dicale and indirectly by the European Community Commission. The editors are particularly pleased to express their gratitude to these Institutions. The presence of a speaker from the General Direction of Science, Research and Development in Brussels who talked about the new opportunities offered by the biological programs of the European Community Commission was particularly appreciated. These discussions on transepithelial water permeability and on the cellular mechanisms of action of antidiuretic hormone took place at a particularly suitable time. Important work has been devoted over the last years to determining the fine structure of the apical plasma membrane and the biochemical nature of the intramembrane particle aggregates that are induced by the hormone and which, as most workers agree, play a crucial role in water permeability modification. The present proceedings present two types of contribution: firstly the princeps papers which according to the standards of Biology of the Cell/Biologie Cellulaire have been submitted for review, and secondly the abstracts of the platform and poster communications presented during the meeting. The first two chapters are related to the initial steps of the hormonal action and to the major cellular factors that control epithelial permeability. These are followed by various morphological contributions relating to the fine structure of the cytoskeleton and to intramembrane particle aggregates. Several articles are then devoted to the biochemical approach to the problem: to technics for fractionating the epithelial cells and for isolating the apical components and to the description of major proteic components and putative enzymatic markers of the apical barrier. Finally, two important chapters concern comparative aspects of water permeability, the associated solute transport and a discussion of cell volume regulation. We take this opportunity to offer our warm thanks to our colleagues whose enthusiasm and numerous contributions ensured the success of the meeting. The help of Biology of the Cell/Biologie Cellulaire and particularly of Professor Daniel Sandoz, its editor.in-chief, is gratefully acknowledged. We are also greatly indebted to all those who organised the practical details of the meeting and the preparation of this volume, and to the Institut Scientifique Roussel for its financial support.