Beschreibung
The mechanisms by which animals regulate the volume and composition of their body fluids has long had a particular fascination for students of biology. As a consequence, the subject can lay claim to an impressive record of ground breaking scientific achievements as well as a provocative body of philosophical speculation concerning the role of the system in the origin and evolution of life. Indeed, the entire concept of homeostasis on which so much of o~r current biologic thinking is based, derives from Claude Bernard's pioneering exploration of the forces that determine the composition of this 'internal sea'. Other seminal achievements credited to this area of inquiry include the first description of a genetically transmitted human disease (familial neurogenic diabetes insipidus); the first isolation sequencing and synthesis of a peptide hormone (vasopressin and oxytocin); the first demonstration of peptide hormone synthesis by way of a larger protein precursor; the first description of resistance to the biologic actions of a hormone (nephrogenic diabetes insipidus); and the conceptual realization of the unique counter-current mechanism that permits concentration of the urine. This record of far reaching and fundamental advances has been distinguished by many fruitful inter actions between clinical and basic science.
Autorenporträt
Inhaltsangabe1 Basal mechanisms of water-salt homeostasis.- 1.1 Body water distribution and osmotic concentration.- 1.2 Balance state.- 1.3 Regulation of extracellular fluid volume (the control of sodium balance).- 1.3.1 Reflex arc.- 1.3.2 Volume depletion.- 1.3.3 Volume expansion.- 1.4 Regulation of extracellular fluid osmolality (the control of water balance).- 1.4.1 Immediate, "first line" response to alterations of ECF osmolality.- 1.4.2 Osmoregulation at the cellular level.- 1.4.3 Osmoregulation at the level of the organism.- 2 Hypothalamo-neurohypophyseal hormones and neurophysins.- 2.1 Arginine-vasopressin (AVP) and lysine-vasopressin (LVP).- 2.2 Oxytocin (OT).- 2.3 Other naturally occurring nonapeptides in mammals.- 2.3.1 Arginine-vasotocin (AVT).- 2.3.2 Novel oxytocin-vasotocin-like material (OT-VT-like material).- 2.4 Neurohypophyseal peptides without established hormonal activity.- 2.4.1 Hormone-associated neurophysins (NP).- 2.4.2 Vasopressin-associated glycopeptide.- 3 Neurosecretion.- 3.1 Neural organization of the vasopressinergic system.- 3.1.1 Neurons producing vasopressin and oxytocin.- 3.1.2 Fiber projections of vasopressinergic neurons.- 3.1.3 Afferent inputs to the supraoptic and paraventricular nuclei.- 3.1.4 Immunoreactive vasopressin in peripheral tissues.- 4 Biosynthesis, transport and release of vasopressin.- 4.1 Structural organization of vasopressin gene.- 4.2 Posttranslational processing of the vasopressin precursor.- 4.3 Regulation of the vasopressin gene expression.- 4.4 The Brattleboro rat - an animal model of hereditary neurogenic (central) diabetes insipidus.- 4.5 Vasopressin release from the neurohypophysis.- 5 Regulation of vasopressin secretion and thirst.- 5.1 Osmoreceptor mediated regulation of vasopressin and thirst.- 5.1.1 Hypothalamic osmoreceptors and/or sodium sensors.- 5.1.2 Peripheral osmoreceptors and exteroceptive receptors (the potodiuretic reflex).- 5.1.3 Functional properties of the osmoregulatory system of vasopressin secretion.- 5.2 Functional properties of the osmoregulatory system regulating thirst.- 5.3 Functional relationship between osmotically stimulated AVP secretion and thirst.- 5.3.1 Changes in osmotic thresholds for vasopressin secretion and thirst.- 5.3.2 Changes in sensitivity of the osmoregulatory system of vasopressin secretion and thirst.- 5.4 Nonosmotic regulation of vasopressin secretion.- 5.4.1 Hemodynamic regulation of AVP secretion.- 5.4.2 Emetic regulation of vasopressin secretion.- 5.4.3 Glycopenic regulation of vasopressin secretion.- 5.4.4 Menstrual cycle and normal pregnancy.- 5.4.5 Pharmacologic agents and endotoxin.- 5.4.6 Hypoxia and hypercapnia.- 5.4.7 Intracranial hypertension.- 5.4.8 Stress.- 5.4.9 Ambient temperature.- 6 Vasopressin assays.- 6.1 Bioassays.- 6.2 Radioimmunoassays (RIA).- 6.2.1 Vasopressin in plasma.- 6.2.2 Vasopressin in urine.- 6.2.3 Vasopressin in cerebrospinal fluid.- 7 Receptors and synthetic analogs of vasopressin.- 7.1 Vasopressin receptors.- 7.1.1 V1 (pressor) receptors.- 7.1.2 V2 (antidiuretic) receptors.- 7.1.3 Novel vasopressin receptors.- 7.2 Regulation of vasopressin receptors.- 7.2.1 Receptor down- and upregulation.- 7.2.2 Multihormonal control of adenylate cyclase.- 7.2.3 Interactions between the V1 and V2 receptor signals; the role of endogenous prostaglandins.- 7.3 Synthetic analogs of vasopressin.- 7.3.1 Selective V2 (antidiuretic) agonists.- 7.3.2 Selective V1 (pressor) agonists.- 7.3.3 Selective V1 (pressor) antagonists.- 7.3.4 Selective V2 (antidiuretic) antagonists - "aquaretics".- 8 Vasopressin and renal regulation of water homeostasis.- 8.1 Renal osmoregulatory performance -the osmotically free water concept.- 8.1.1 Generation and maintenance of a cortico-medullary osmotic gradient.- 8.1.2 Processes of generation of solute-free water and of the cortico-medullary osmotic gradient (countercurrent multiplier).- 8.1.3 Processes involved in the maintenance of the cortico-medullary osmotic gradient (medullary microcirculati
