Ion Transport and Water Movement

1987 ◽  
Vol 66 (2_suppl) ◽  
pp. 638-647 ◽  
Author(s):  
J. R. Martinez
Keyword(s):  
Cell Membrane ◽  
Ion Transport ◽  
Water Movement ◽  
Transport Processes ◽  
Hormonal Control ◽  
Dual Process ◽  
Transport Systems ◽  
Osmotic Gradient ◽  
Basolateral Cell Membrane ◽  
Ion Movements

Secretion of water and electrolytes in salivary glands occurs by a dual process involving the formation of a plasma-like, isotonic primary-secretion in salivary acini and its subsequent modification in salivary-ducts by the removal and addition of specific ions. The mechanisms underlying the formation of primary acinar secretion have been investigated with a number of experimental approaches such as electrophysiology, the measurement of ion transport in gland fragments and dispersed acinar cells, and the evaluation of the ionic requirements for secretion in isolated, perfused gland preparations. The ac-cumulated evidence suggests that salivary secretion is formed by a complex interaction between passive and active ion movements across acinar cell membranes, resulting in the trans-acinar movement of Cl and Na* and, by the osmotic gradient which develops, of water. A major consequence of stimulation is the release of K+ through Ca++ -and voltage-sensitive channels and its subsequent recycling back into the cells by ouabain- and furosemide-sensitive transport systems. This results in NaCl uptake across the basolateral cell membrane and the subsequent efflux of Cl through luminal membrane channels, which also appear to be sensitive to cellular Ca++. The rates of these various ion movements appear to be, therefore, closely linked and interdependent. Ductal modification of the primary secretion has been studied in microperfused duct preparations. The evidence likewise indicates that it involves interactions between complex conductance pathways in the luminal cell membrane and a Na, K pump present in the basolateral cell membrane and that it is under autonomic and hormonal control. Activation of ductal transport mechanisms results in NaCl reabsorption and KHCO3 secretion. Final saliva thus differs from primary secretion in electrolyte composition and, because water permeability is low in the duct epithelium, becomes hypotonic. Alterations in fluid and electrolyte secretion such as those observed in disease can result, therefore, from disturbances in one or more of these complex transport processes in acinar or duct cells.

Ion Transport and Water Movement

1987 ◽  
Vol 66 (1_suppl) ◽  
pp. 638-647 ◽  
Author(s):  
J. R. Martinez
Keyword(s):  
Cell Membrane ◽  
Ion Transport ◽  
Water Movement ◽  
Transport Processes ◽  
Hormonal Control ◽  
Dual Process ◽  
Transport Systems ◽  
Osmotic Gradient ◽  
Basolateral Cell Membrane ◽  
Ion Movements

Secretion of water and electrolytes in salivary glands occurs by a dual process involving the formation of a plasma-like, isotonic primary-secretion in salivary acini and its subsequent modification in salivary-ducts by the removal and addition of specific ions. The mechanisms underlying the formation of primary acinar secretion have been investigated with a number of experimental approaches such as electrophysiology, the measurement of ion transport in gland fragments and dispersed acinar cells, and the evaluation of the ionic requirements for secretion in isolated, perfused gland preparations. The accumulated evidence suggests that salivary secretion is formed by a complex interaction between passive and active ion movements across acinar cell membranes, resulting in the trans-acinar movement of CI and Na+ and, by the osmotic gradient which develops, of water. A major consequence of stimulation is the release of K + through Ca++ -and voltage-sensitive channels and its subsequent recycling back into the cells by ouabain- and furosemide-sensitive transport systems. This results in NaCl uptake across the basolateral cell membrane and the subsequent efflux of CI through luminal membrane channels, which also appear to be sensitive to cellular Ca + +. The rates of these various ion movements appear to be, therefore, closely linked and interdependent. Ductal modification of the primary secretion has been studied in microperfused duct preparations. The evidence likewise indicates that it involves interactions between complex conductance pathways in the luminal cell membrane and a Na, K pump present in the basolateral cell membrane and that it is under autonomic and hormonal control. Activation of ductal transport mechanisms results in NaCl reabsorption and KHCO3 secretion. Final saliva thus differs from primary secretion in electrolyte composition and, because water permeability is low in the duct epithelium, becomes hypotonic. Alterations in fluid and electrolyte secretion such as those observed in disease can result, therefore, from disturbances in one or more of these complex transport processes in acinar or duct cells.

scholarly journals The Important Role of Ion Transport System in Cervical Cancer

2021 ◽  
Vol 23 (1) ◽  
pp. 333
Author(s):  
Yih-Fung Chen ◽  
Meng-Ru Shen
Keyword(s):  
Cervical Cancer ◽  
Epithelial Cells ◽  
Ion Transport ◽  
Cell Volume ◽  
Volume Regulation ◽  
Gynecological Cancer ◽  
Cell Volume Regulation ◽  
Hpv Infection ◽  
Transport Processes ◽  
Transport Systems

Cervical cancer is a significant gynecological cancer and causes cancer-related deaths worldwide. Human papillomavirus (HPV) is implicated in the etiology of cervical malignancy. However, much evidence indicates that HPV infection is a necessary but not sufficient cause in cervical carcinogenesis. Therefore, the cellular pathophysiology of cervical cancer is worthy of study. This review summarizes the recent findings concerning the ion transport processes involved in cell volume regulation and intracellular Ca2+ homeostasis of epithelial cells and how these transport systems are themselves regulated by the tumor microenvironment. For cell volume regulation, we focused on the volume-sensitive Cl− channels and K+-Cl− cotransporter (KCC) family, important regulators for ionic and osmotic homeostasis of epithelial cells. Regarding intracellular Ca2+ homeostasis, the Ca2+ store sensor STIM molecules and plasma membrane Ca2+ channel Orai proteins, the predominant Ca2+ entry mechanism in epithelial cells, are discussed. Furthermore, we evaluate the potential of these membrane ion transport systems as diagnostic biomarkers and pharmacological interventions and highlight the challenges.

Ion transport in hypertension: are changes in the cell membrane responsible?

1986 ◽  
Vol 71 (3) ◽  
pp. 225-230 ◽  
Author(s):  
Robert F. Bing ◽  
Anthony M. Heagerty ◽  
Herbert Thurston ◽  
John D. Swales
Keyword(s):  
Blood Pressure ◽  
Cell Membrane ◽  
Ion Transport ◽  
Calcium Binding ◽  
Dietary Intervention ◽  
Lipid Fraction ◽  
Smooth Muscle Contraction ◽  
Transport Processes ◽  
Membrane Properties ◽  
And Function

Disturbances in several, distinct cell membrane ion transport processes have been demonstrated in essential hypertension but their variable relationship to blood pressure in different populations has made it difficult to achieve a unifying hypothesis. We suggest that altered composition of the lipid fraction of the cell membrane is the common underlying factor. This would produce many of the reported perturbations of cell membrane properties and function, not all of which relate directly to the development of hypertension, but which act as markers for the underlying abnormality. However, functions such as phosphoinositol turnover, calcium binding and Ca2+,Mg2+-ATPase dependent calcium efflux, which are influenced by the lipid composition of the membrane, provide a possible link between the membrane disturbance, intracellular calcium, vascular smooth muscle contraction and blood pressure. Alteration in the lipid content of the cell membrane not only provides an explanation for the variability in the ion transport abnormalities between populations but perhaps also for some of the variability in blood pressure within a single population. It also provides a potential means of influencing blood pressure by dietary intervention.

scholarly journals Biochemical effects of urapidil on red cell membrane ion transport systems in a population of elderly essential hypertensives.

1991 ◽  
Vol 67 (785) ◽  
pp. 252-255
Author(s):  
R. Antonicelli ◽  
E. Balducci ◽  
G. Lipponi ◽  
C. Lucantoni ◽  
R. Gaetti ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Ion Transport ◽  
Transport Systems ◽  
Red Cell ◽  
Red Cell Membrane ◽  
Biochemical Effects ◽  
Membrane Ion Transport

Sodium-Potassium-Adenosinetriphosphatase-Dependent Sodium Transport in the Kidney: Hormonal Control

2001 ◽  
Vol 81 (1) ◽  
pp. 345-418 ◽  
Author(s):  
Eric Féraille ◽  
Alain Doucet
Keyword(s):  
Signaling Pathways ◽  
Sodium Transport ◽  
Molecular Level ◽  
Transport Processes ◽  
Hormonal Control ◽  
Transport Systems ◽  
Sodium Reabsorption ◽  
Thick Ascending Limb ◽  
Nephron Segments ◽  
Structural And Functional Properties

Tubular reabsorption of filtered sodium is quantitatively the main contribution of kidneys to salt and water homeostasis. The transcellular reabsorption of sodium proceeds by a two-step mechanism: Na+-K+-ATPase-energized basolateral active extrusion of sodium permits passive apical entry through various sodium transport systems. In the past 15 years, most of the renal sodium transport systems (Na+-K+-ATPase, channels, cotransporters, and exchangers) have been characterized at a molecular level. Coupled to the methods developed during the 1965–1985 decades to circumvent kidney heterogeneity and analyze sodium transport at the level of single nephron segments, cloning of the transporters allowed us to move our understanding of hormone regulation of sodium transport from a cellular to a molecular level. The main purpose of this review is to analyze how molecular events at the transporter level account for the physiological changes in tubular handling of sodium promoted by hormones. In recent years, it also became obvious that intracellular signaling pathways interacted with each other, leading to synergisms or antagonisms. A second aim of this review is therefore to analyze the integrated network of signaling pathways underlying hormone action. Given the central role of Na+-K+-ATPase in sodium reabsorption, the first part of this review focuses on its structural and functional properties, with a special mention of the specificity of Na+-K+-ATPase expressed in renal tubule. In a second part, the general mechanisms of hormone signaling are briefly introduced before a more detailed discussion of the nephron segment-specific expression of hormone receptors and signaling pathways. The three following parts integrate the molecular and physiological aspects of the hormonal regulation of sodium transport processes in three nephron segments: the proximal tubule, the thick ascending limb of Henle's loop, and the collecting duct.

Developmental Aspects of Fluid and Electrolyte Secretion in Salivary Glands

1994 ◽  
Vol 5 (3) ◽  
pp. 281-290 ◽  
Author(s):  
J. Ricardo Martinez
Keyword(s):  
Signal Transduction ◽  
Ion Transport ◽  
Salivary Glands ◽  
Signal Transduction Pathway ◽  
Cholinergic Receptors ◽  
Transport Systems ◽  
Secretory Process ◽  
Osmotic Gradient ◽  
Monovalent Ion ◽  
Electrolyte Secretion

The salivary glands of rodents undergo considerable cytodifferentiation after birth and are useful models for the study of functional development, including the mechanisms of fluid and electrolyte secretion. In the rat submandibular gland, secretion of salivary fluid cannot be elicited until approximately 2 weeks of age. The currently accepted model of salivary fluid secretion indicates that this process depends on the activation, on stimulation of cholinergic receptors, of several ion transport systems, resulting in a net transport of osmotically active ions (primarily Cl- and Na +) across the acinar epithelium. This creates the necessary osmotic gradient for the transacinar movement of water. The process is associated with a signal transduction pathway involving the formation of phosphoinositide products (primarily inositol triphosphate or IP3) and the mobilization of Ca2+. The latter regulates monovalent ion conductances (K+, CI-), which are critical for the secretory process. Immature submandibular glands and cells of early postnatal rats have a lower density of cholinergic receptors and release less K+ and Cl- than mature cells and gradually develop other ion transport systems (such as a Na, K, 2Cl cotransport system) involved in the secretory process. Surprisingly, they form more IP3 and show a larger increase in cytosolic Ca2+ when stimulated with maximal or supramaximal concentrations of agonist. Therefore, they show some interesting dissociations in the signal transduction mechanism that suggest differences in the coupling between receptors and membrane phosphoinositides, between IP3 and IP3-dependent Ca2+ stores, and between the Ca2+ signal and the monovalent ion transport systems which are critical for secretion.

OSMOTIC INHIBITION OF THE NATRIFERIC RESPONSE OF THE TOAD URINARY BLADDER TO VASOPRESSIN

1975 ◽  
Vol 67 (1) ◽  
pp. 119-125
Author(s):  
P. J. BENTLEY
Keyword(s):  
Urinary Bladder ◽  
Water Movement ◽  
Short Circuit ◽  
Electrical Potential ◽  
Short Circuit Current ◽  
Toad Bladder ◽  
Toad Urinary Bladder ◽  
Electrical Potential Difference ◽  
Osmotic Gradient

SUMMARY The electrical potential difference and short-circuit current (scc, reflecting active transmural sodium transport) across the toad urinary bladder in vitro was unaffected by the presence of hypo-osmotic solutions bathing the mucosal (urinary) surface, providing that the transmural flow of water was small. Vasopressin increased the scc across the toad bladder (the natriferic response), but this stimulation was considerably reduced in the presence of a hypo-osmotic solution on the mucosal side, conditions under which water transfer across the membrane was also increased. This inhibition of the natriferic response did not depend on the direction of the water movement, for if the osmotic gradient was the opposite way to that which normally occurs, the response to vasopressin was still reduced. The natriferic response to cyclic AMP was also inhibited in the presence of an osmotic gradient. Aldosterone increased the scc and Na+ transport across the toad bladder but this response was not changed when an osmotic gradient was present. The physiological implications of these observations and the possible mechanisms involved are discussed.

Insulin resistance, hypertension and cellular ion transport systems

1992 ◽  
Vol 29 (3-4) ◽  
pp. 196-200 ◽  
Author(s):  
Anna Solini ◽  
Ralph A. DeFronzo
Keyword(s):  
Insulin Resistance ◽  
Ion Transport ◽  
Transport Systems

Transport Phenomena and Properties in Treelike Networks

2016 ◽  
Vol 68 (4) ◽  
Author(s):  
Peng Xu ◽  
Agus Pulung Sasmito ◽  
Boming Yu ◽  
Arun Sadashiv Mujumdar
Keyword(s):  
Transport Properties ◽  
Scaling Laws ◽  
Transport Phenomena ◽  
Transport Processes ◽  
Research Progress ◽  
Transport Systems ◽  
Transport Mechanisms ◽  
Branching Structures ◽  
Flow And Heat Transfer ◽  
Flow Heat

Treelike structures abound in natural as well as man-made transport systems, which have fascinated multidisciplinary researchers to study the transport phenomena and properties and understand the transport mechanisms of treelike structures for decades. The fluid flow and heat transfer in treelike networks have received an increasing attention over the past decade as the highly efficient transport processes observed in natural treelike structures can provide useful hints for optimal solutions to many engineering and industrial problems. This review paper attempts to present the background and research progress made in recent years on the transport phenomenon in treelike networks as well as technological applications of treelike structures. The subtopics included are optimization of branching structures, scaling laws of treelike networks, and transport properties for laminar flow, turbulent flow, heat conduction, and heat convection in treelike networks. Analytical expressions for the effective transport properties have been derived based on deterministic treelike networks, and the effect of branching parameters on the transport properties of treelike networks has also been discussed. Furthermore, numerical simulation results for treelike microchannel networks are presented as well. The proposed transport properties may be beneficial to understand the transport mechanisms of branching structures and promote the applications of treelike networks in engineering and industry.

Basolateral Cl− uptake mechanisms in Xenopus laevis lung epithelium

2010 ◽  
Vol 299 (1) ◽  
pp. R92-R100 ◽  
Author(s):  
Jens Berger ◽  
Martin Hardt ◽  
Wolfgang G. Clauss ◽  
Martin Fronius
Keyword(s):  
Xenopus Laevis ◽  
Ion Transport ◽  
Anion Exchanger ◽  
Short Circuit ◽  
Ussing Chamber ◽  
Short Circuit Current ◽  
Transport Processes ◽  
Lung Epithelium ◽  
Active Ion Transport ◽  
Uptake Mechanisms

A thin liquid layer covers the lungs of air-breathing vertebrates. Active ion transport processes via the pulmonary epithelial cells regulate the maintenance of this layer. This study focuses on basolateral Cl− uptake mechanisms in native lungs of Xenopus laevis and the involvement of the Na+/K+/2 Cl− cotransporter (NKCC) and HCO3−/Cl− anion exchanger (AE), in particular. Western blot analysis and immunofluorescence staining revealed the expression of the NKCC protein in the Xenopus lung. Ussing chamber experiments demonstrated that the NKCC inhibitors (bumetanide and furosemide) were ineffective at blocking the cotransporter under basal conditions, as well as under pharmacologically stimulated Cl−-secreting conditions (forskolin and chlorzoxazone application). However, functional evidence for the NKCC was detected by generating a transepithelial Cl− gradient. Further, we were interested in the involvement of the HCO3−/Cl− anion exchanger to transepithelial ion transport processes. Basolateral application of DIDS, an inhibitor of the AE, resulted in a significantly decreased the short-circuit current (ISC). The effect of DIDS was diminished by acetazolamide and reduced by increased external HCO3− concentrations. Cl− secretion induced by forskolin was decreased by DIDS, but this effect was abolished in the presence of HCO3−. These experiments indicate that the AE at least partially contributes to Cl− secretion. Taken together, our data show that in Xenopus lung epithelia, the AE, rather than the NKCC, is involved in basolateral Cl− uptake, which contrasts with the common model for Cl− secretion in pulmonary epithelia.

Sign in / Sign up

Export Citation Format

Share Document