Uptake of sodium and chloride by freshwater mussels

1979 ◽  
Vol 57 (1) ◽  
pp. 156-160 ◽  
Author(s):  
Thomas H. Dietz
Keyword(s):  
Steady State ◽  
North America ◽  
Ion Transport ◽  
Brackish Water ◽  
Major Ions ◽  
Chloride Transport ◽  
Freshwater Mussels ◽  
Transport Systems ◽  
Freshwater Bivalves ◽  
Chloride Influx

Ion transport rates were measured in six species representing the four families of freshwater bivalves in North America. Sodium and chloride transport systems function independently in all of the species. The unionid steady-state influx of Na and Cl was about 1 μ equiv/g dry tissue per hour. Margaritifera hembeli Na influx was about 5 μ equiv/g dry tissue per hour and they were in a positive Na balance. Chloride influx by M. hembeli was similar to the unionids. The Sphaeriacea transport Na and Cl at significantly higher rates than Unionacea. Corbicula manilensis Na and Cl influx was about 9 μ equiv/g dry tissue per hour. Sphaerium transversum Cl influx was similar to C. manilensis; however, Na influx was twice as high. The higher transport rates of the Sphaeriacea are similar to brackish-water animals. Sodium, Ca, and Cl are major ions in the blood of all species. Bicarbonate is a major anion (19–12 mM/L) in all species except C. manilensis (4 mM/L).

scholarly journals Chloride Influx into Citrus Leaf Slices

1970 ◽  
Vol 23 (4) ◽  
pp. 953 ◽  
Author(s):  
JB Robinson ◽  
FA Smith
Keyword(s):  
Alternative Energy ◽  
Chloride Transport ◽  
Chloride Concentration ◽  
Transport Systems ◽  
Anaerobic Conditions ◽  
Alternative Energy Source ◽  
Cyclic Photophosphorylation ◽  
Ionic Relations ◽  
Citrus Leaves ◽  
Chloride Influx

The influx of 36Cl has been measured in slices of citrus leaves. The influx increases with increasing external chloride concentration. The shape of the influx v. concentration curve depends on the nature and concentration of the accompanying cations (Na+ and K+). There is no evidence for the two distinct chloride transport systems reported by other workers. Chloride influx was not stimulated by light under aerobic conditions and was sensitive to 2,4-dinitrophenol at uncoupling concentrations. Under anaerobic conditions influx was maintained by light but severely limited by dark conditions. 3-(chlorophenyl)-I,I-dimethylurea did not affect aerobic influx and only high levels (5 X 10-OM) affected the anaerobic influx in the light. It is proposed that chloride influx is normally dependent on oxidative phosphorylation but that cyclic photophosphorylation may provide an alternative energy source. The implications of these results are discussed with respect to ionic relations of whole leaves and salinity damage.

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

The anterior and posterior ‘stomach’ regions of larval Aedes aegypti midgut: regional specialization of ion transport and stimulation by 5-hydroxytryptamine

1999 ◽  
Vol 202 (3) ◽  
pp. 247-252 ◽  
Author(s):  
T.M. Clark ◽  
A. Koch ◽  
D.F. Moffett
Keyword(s):  
Steady State ◽  
Aedes Aegypti ◽  
Ion Transport ◽  
Malpighian Tubules ◽  
Transport Mechanisms ◽  
Regional Specialization ◽  
Negative Deflection ◽  
Electrical Polarity

The ‘stomach’ region of the larval mosquito midgut is divided into histologically distinct anterior and posterior regions. Anterior stomach perfused symmetrically with saline in vitro had an initial transepithelial potential (TEP) of −66 mV (lumen negative) that decayed within 10–15 min to a steady-state TEP near −10 mV that was maintained for at least 1 h. Lumen-positive TEPs were never observed in the anterior stomach. The initial TEP of the perfused posterior stomach was opposite in polarity, but similar in magnitude, to that of the anterior stomach, measuring +75 mV (lumen positive). This initial TEP of the posterior stomach decayed rapidly at first, then more slowly, eventually reversing the electrical polarity of the epithelium as lumen-negative TEPs were recorded in all preparations within 70 min. Nanomolar concentrations of the biogenic amine 5-hydroxytryptamine (5-HT, serotonin) stimulated both regions, causing a negative deflection of the TEP of the anterior stomach and a positive deflection of the TEP of the posterior stomach. Phorbol 12,13-diacetate also caused a negative deflection of the TEP of the anterior stomach, but had no effect on the TEP of the posterior stomach. These data demonstrate that 5-HT stimulates region-specific ion-transport mechanisms in the stomach of Aedes aegypti and suggest that 5-HT coordinates the actions of the Malpighian tubules and midgut in the maintenance of an appropriate hemolymph composition in vivo.

Chloride transport by the cortical and outer medullary collecting duct

1987 ◽  
Vol 253 (2) ◽  
pp. F203-F212 ◽  
Author(s):  
V. L. Schuster ◽  
J. B. Stokes
Keyword(s):  
Chloride Transport ◽  
Collecting Duct ◽  
Exchange Process ◽  
Basolateral Membrane ◽  
Fine Tuning ◽  
Transport Systems ◽  
Acid Base ◽  
Intercalated Cell ◽  
Cl Channel ◽  
Collecting Tubule

The processes by which chloride is transported by the cortical and outer medullary collecting tubule have been most extensively studied using in vitro microperfusion of rabbit tubules. Chloride appears to be transported by three major mechanisms. First, Cl can be actively reabsorbed by an electroneutral Cl-HCO3 exchanger localized to the apical membrane of the HCO3-secreting (beta-type) intercalated cell. Cl exits this cell via a basolateral Cl channel. This anion exchange process can also operate in a Cl self-exchange mode, is stimulated acutely by beta-adrenergic agonists and cAMP, and is regulated chronically by in vivo acid-base status. Second, Cl can diffuse passively down electrochemical gradients via the paracellular pathway. Although this pathway does not appear to be selectively permeable to Cl, it is large enough to allow for significant passive reabsorption. Third, Cl undergoes recycling across the basolateral membrane of the H+-secreting (alpha-type) intercalated cell. HCO3 exit from this cell brings Cl into the cell via electroneutral Cl-HCO3 exchange; Cl then exits the cell via a Cl channel. Cl transport is thus required for acidification and alkalinization of the urine. Both of these processes exist in the cortical collecting tubule. Their simultaneous operation allows fine tuning of acid-base excretion. In addition, these transport systems, when functioning at equal rates, effect apparent electrogenic net Cl absorption without changing net HCO3 transport. These systems may play an important role in regulating Cl balance.

scholarly journals Assessment of Lentiviral Vector Mediated CFTR Correction in Mice Using an Improved Rapid in vivo Nasal Potential Difference Measurement Protocol

2021 ◽  
Vol 12 ◽  
Author(s):  
P. Cmielewski ◽  
J. Delhove ◽  
M. Donnelley ◽  
D. Parsons
Keyword(s):  
Ion Transport ◽  
Lentiviral Vector ◽  
Chloride Transport ◽  
Diagnostic Technique ◽  
Potential Difference ◽  
Third Generation ◽  
Flow Rates ◽  
Measurement Protocol ◽  
Nasal Potential Difference

Cystic Fibrosis (CF) is caused by a defect in the CF transmembrane conductance regulator (CFTR) gene responsible for epithelial ion transport. Nasal potential difference (PD) measurement is a well established diagnostic technique for assessing the efficacy of therapies in CF patients and animal models. The aim was to establish a rapid nasal PD protocol in mice and quantify the efficacy of lentiviral (LV) vector-based CFTR gene therapy. Anaesthetised wild-type (WT) and CF mice were non-surgically intubated and nasal PD measurements were made using a range of buffer flow rates. Addition of the cAMP agonist, isoproterenol, to the buffer sequence was then examined. The optimised rapid PD technique was then used to assess CFTR function produced by second and third generation LV-CFTR vectors. V5 epitope tagged-CFTR in nasal tissue was identified by immunohistochemistry. When intubated, mice tolerated higher flow rates. Isoproterenol could discriminate between WT and CF mice. Improved chloride transport was observed for the second and third generation LV-CFTR vectors, with up to 60% correction of the cAMP-driven chloride response towards WT. V5-CFTR was located in ciliated epithelial cells. The rapid PD technique enables improved functional assessment of the bioelectrical ion transport defect for both current and potential CF therapies.

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