Current Topics in Membranes and Transport, Volume 9Автор:
Felix Bronner, A. KleinzellerИздательство:
Academic Press Inc.,U.S.Год:
0121533093 / 9780121533090Страниц:
Over the past decade, a large number of papers have been published dealing with applications of nuclear magnetic resonance (NMR) spectroscopy to physiological problems. Of particular interest have been the efforts to define the nature and state of the intracellular fluids. The present review in no way constitutes an exhaustive compilation of the published literature; rather, we have specifically tried to communicate the nature and limitations of present NMR technique and the basic concepts that have been proposed to account for the data and to assess the relative significance and promise of the various NMR approaches in current use.
In this introductory section we would like to place the biological applications of NMR spectroscopy in perspective, albeit briefly. Our main point here is the fact that NMR techniques constitute one of several powerful approaches currently being used to define the state of the intracellular fluids and that these different approaches provide different complementary information.
It has long been recognized that the nature and state of intracellular fluids is one of the most crucial problems confroilting cell physiologists. The state and intracellular distribution of ions clearly play a
pivotal role in regulating certain cellular functions; as a familiar example, the intracellular distribution of Ca2 between the cytoplasm and sarcoplasmic reticulum is a primary determinant of the state of
contraction of striated muscle. To what extent subcellular redistribution of water and ions may play a role in regulating other physiological and pathophysiological processes, such as cell volume regulation,
transepithelial transport, gene activity, blast transformation, and malignant transformation, is conjectural. However, it is clear that definition of the transport processes responsible for movement of water and ions across the plasma membrane is altogether hopeless until the driving forces acting on these species can be measured. Since the composition of the extracellular fluids can usually be determined, the central problem is reduced to a definition of the activities of ions and water within the cytoplasm an’d within the subcellular organelles............