The philosophy of this monograph is to apply an interdisciplinary approach and thus outline the latest advances in such areas as absorption mechanisms of nutrients (sugars, amino acids, dipeptides) and membrane digestion in the small intestine of vertebrates. The novel updates to the known electrophysiological short-circuit current techniques employed allow for discussing the newest evidence concerning the molecular mechanisms of transport, such as the maximum rate and the affinity of the transporters for a nutrient. Some other topics touched upon concern the roles played by unstirred layers of liquid near the membrane surface, the transport of water and the mechanisms of osmotic phenomena, as well as transport processes control. The validity of the methods developed is illustrated by an analysis of absorption under satiety conditions as compared to fasting conditions and absorption in young and old rats. The probable prospects of applying this biophysical method described to clinical investigations are best demonstrated using specific examples.
State-of-the art concepts and the understanding of epithelial transport phenomena are covered based on the results obtained by the author in the course of his own lifetime research, carried out predominantly in the laboratories headed by the late Prof. A. Ugolev, as well as on data from other researchers.
Preface by the author 14 Preface by Dr. D.D.F. Loo 17 Chapter 1. Transport processes in epithelial tissues 19 Chapter 2. Investigative techniques of sodium transport in the epitheliocyte 53 Chapter 3. Some aspects of an adequate short circuit current techinque 67 Chapter 4. Osmotic phenomena and water fluxes 77 Chapter 5. Transport of monosaccharides and the contribution to its study made by electrophysiological techniques 89 Chapter 6. The single response method 105 Chapter 7. Unstirred layers of the fluid at the mucosa surface 115 Chapter 8. Regulation of sodium transport in a small intestine 125 Chapter 9. Molecular mechanisms of the coupled transport of glucose 155 Chapter 10. Hydrolysis-dependent disaccharide transport 185 CHAPTER 11. Transport systems for amino acids 199 CHAPTER 12. Mechanisms of peptide transport in the small intestine 215 CHAPTER 13. Gerontological aspects of absorption and membrane digestion in the small intestine 221 Chapter 14. intestinal Absorption at Satiety, fasting and refeeding 227 CHAPTER 15. Clinical study of absorption and membrane digestion 233 Chapter 16. Conclusions 241 Acknowledgements 250 Abbreviations and designations 251 References 253