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  • 1
    Electronic Resource
    Electronic Resource
    Differential effects of ADH on sodium, chloride, potassium, calcium and magnesium transport in cortical and medullary thick ascending limbs of mouse nephron (1988)
    Springer
    Pflügers Archiv 412 (1988), S. 516-523 
    Details
    ISSN: 1432-2013
    Keywords: ADH ; Transepithelial ion net fluxes ; Na+, Cl−, K+, Ca2+ and Mg2+ transport ; Electron microprobe ; Mouse kidney ; Cortical and medullary thick ascending limb of Henle's loop ; In vitro microperfusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of antidiuretic hormone (arginine vasopressin, AVP) on transepithelial Na+, Cl−, K+, Ca2+ and Mg2+ net transports was investigated in medullary (mTAL) and cortical (cTAL) segments of the thick ascending limb (TAL) of mouse nephron, perfused in vitro. Transepithelial net fluxes (J Na +,J Cl −,J K +,J Ca 2+,J Mg 2+) were determined by electron probe analysis of the collected tubular fluid. Transepithelial potential difference (PDte) and transepithelial resistance (Rte) were measured simultaneously. cTAL segments were bathed and perfused with isoosmolal, HCO 3 − containing Ringer solutions, mTAL segments were bathed and perfused with isoosmolal HCO 3 − free Ringer solutions. In cTAL segments, AVP (10−10 mol·l−1) significantly increasedJ Mg 2+ andJ Ca 2+ from 0.39±0.08 to 0.58±0.10 and from 0.86±0.13 to 1.19±0.15 pmol·min−1 mm−1 respectively. NeitherJ Na + norJ Cl −, (J Na +: 213±30 versus 221±28 pmol·min−1 mm−1,J Cl −: 206±30 versus 220±23 pmol·min−1 mm−1) nor PDte (13.4±1.3 mV versus 14.1±1.9 mV) or Rte (24.6±6.5Ω cm2 versus 22.6±6.4Ω cm2) were significantly changed by AVP. No significant effect of AVP on net K+ transport was observed. In mTAL segments, Mg2+ and Ca2+ net transports were close to zero and AVP (10−10 mol·l−1) elicited no effect. However NaCl net reabsorption was significantly stimulated by the hormone,J Na + increased from 107±33 to 148±30 andJ Cl − from 121±33 to 165±32 pmol·min−1 mm−1. The rise inJ NaCl was accompanied by an increase in PDte from 9.0±0.7 to 13.5±0.9 mV and a decrease in Rte from 14.4±2.0 to 11.2±1.7 Ω cm2. No K+ net transport was detected, either under control conditions or in the presence of AVP. To test for a possible effect of HCO 3 − on transepithelial ion fluxes, mTAL segments were bathed and perfused with HCO 3 − containing Ringer solutions. With the exception ofJ Ca 2+ which was significantly different from zero (J Ca 2+: 0.26±0.06 pmol·min−1 mm−1), net transepithelial fluxes of Na+, Cl−, K+ and Mg2+ were unaffected by HCO 3 − . In the presence of AVP,J Mg 2+ andJ Ca 2+ were unaltered whereasJ NaCl was stimulated to the same extent as observed in the absence of HCO 3 − . In conclusion our results indicate heterogeneity of response to AVP in cortical and medullary segments of the TAL segment, since AVP stimulates Ca2+ and Mg2+ reabsorption in the cortical part and Na+ and Cl− reabsorption in the medullary part of this nephron segment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00582541
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  • 2
    Electronic Resource
    Electronic Resource
    Hormonal stimulation of Ca2+ and Mg2+ transport in the cortical thick ascending limb of Henle's loop of the mouse: evidence for a change in the paracellular pathway permeability (1993)
    Springer
    Pflügers Archiv 423 (1993), S. 387-396 
    Details
    ISSN: 1432-2013
    Keywords: Ca2+ transport ; Mg2+ transport ; Electron microprobe analysis ; Cortical thick ascending limb ; Furosemide ; Parathyroid hormone ; Paracellular shunt pathway permeability ; Tight junctions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Recent studies from our laboratory have shown that in the cortical thick ascending limb of Henle's loop of the mouse (cTAL) Ca2+ and Mg2+ are reabsorbed passively, via the paracellular shunt pathway. In the present study, cellular mechanisms responsible for the hormone-stimulated Ca2+ and Mg2+ transport were investigated. Transepithelial voltages (PDte) and transepithelial ion net fluxes (J Na, J Cl, J K, J Ca, J Mg) were measured in isolated perfused mouse cTAL segments. Whether parathyroid hormone (PTH) is able to stimulate Ca2+ and Mg2+ reabsorption when active NaCl reabsorption, and thus PDte, is abolished by luminal furosemide was first tested. With symmetrical lumen and bath Ringer's solutions, no Ca2+ and Mg2+ net transport was detectable, either in the absence or in the presence of PTH. In the presence of luminal furosemide and a chemically imposed lumen-to-bath directed NaCl gradient, which generates a lumen-negative PDte, PTH slightly but significantly increased Ca2+ and Mg2+ net secretion. In the presence of luminal furosemide and a chemically imposed bath-to-lumen-directed NaCl gradient, which generates a lumen-positive PDte, PTH slightly but significantly increased Ca2+ and Mg2+ net reabsorption. In view of the observed small effect of PTH on passive Ca2+ and Mg2+ movement, a possible interference of furosemide with the hormonal response was considered. To investigate this possibility, Ca2+ and Mg2+ transport was first stimulated with PTH in tubules under control conditions. Then active NaCl reabsorption was abolished by furosemide and the effect of PTH on J Ca and J Mg measured. In the absence of PDte and under symmetrical conditions, no Ca2+ and Mg2+ transport was detectable, either in the presence or absence of PTH. In the presence of a bath-to-lumen-directed NaCl gradient, Ca2+ and Mg2+ reabsorption was significantly higher in the presence than in the absence of PTH. Finally, when active NaCl transport was not inhibited by furosemide, but reduced by a bath-to-lumen-directed NaCl gradient, PTH strongly increased J Ca and J Mg, whereas only a small increase in PDte was noted. In conclusion, these data suggest that PTH exerts a dual action on Ca2+ and Mg2+ transport in the mouse cTAL by increasing the transepithelial driving force for Ca2+ and Mg2+ reabsorption through hormone-mediated PDte alterations and by modifying the passive permeability for Ca2+ and Mg2+ of the epithelium, very probably at the level of the paracellular shunt pathway.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00374932
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of parathyroid hormone and calcitonin on Na+, Cl−, K+, Mg2+ and Ca2+ transport in cortical and medullary thick ascending limbs of mouse kidney (1990)
    Springer
    Pflügers Archiv 417 (1990), S. 161-167 
    Details
    ISSN: 1432-2013
    Keywords: Parathyroid hormone ; Human calcitonin ; Transepithelial ion net fluxes ; Na+, Cl−, K+, Mg2+, Ca2+ transport ; Electron microprobe analysis-Mouse kidney ; In vitro microperfusion ; Cortical and medullary thick ascending limb of Henle's loop
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of parathyroid hormone (PTH) on transepithelial Na+, Cl−, K+, Ca2+ and Mg2+ transport was investigated in isolated perfused cortical thick ascending limbs (cTAL) and that of human calcitonin (hCT) was tested in both cortical and medullary thick ascending limbs (mTAL) of the mouse nephron. The transepithelial ion net fluxes (J x) were determined by electron probe analysis of the perfused and collected fluids. Simultaneously, the transepithelial voltage (PDte) and resistance (R te) were recorded. In cTAL segments, PTH and hCT significantly stimulated the reabsorption of Na+, Cl−, Ca2+ and Mg2+. hCT generated a net K+ secretion towards the lumen and PTH tended to exert the same effect. Neither PDte nor R te were significantly altered by either PTH or hCT. However, in the post-experimental period a significant decrease in PDte was noted. Time control experiments carried out under similar conditions revealed a significant decrease in PDte with time, which could have masked the hormonal response. In mTAL segments, Mg2+ and Ca2+ transport was close to zero. hCT did not exert any detectable effect on either PDte or J Cl −, J Na + J K +, J Mg 2+ and J Ca 2+ in these segments. In conclusion, our data demonstrate that PTH and hCT stimulate NaCl reabsorption as well as Mg2+ and Ca2+ reabsorption in the cTAL segment of the mouse. These data are in agreement with and extend data obtained in vivo in the rat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00370694
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  • 4
    Electronic Resource
    Electronic Resource
    Stimulation of NaCl reabsorption by antidiuretic hormone in the cortical thick ascending limb of Henle's loop of the mouse (1991)
    Springer
    Pflügers Archiv 419 (1991), S. 212-214 
    Details
    ISSN: 1432-2013
    Keywords: ADH ; Mouse nephron ; Microperfusion ; NaCl transport ; Mg2+ transport ; Ca2+ transport ; Electron microprobe analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of antidiuretic hormone (ADH) on transepithelial Na+, Cl−, Ca2+ and Mg2+ net fluxes (JNa, JCl, JMg, JCa) was investigated in isolated perfused cortical thick ascending limb segments (cTAL) of the mouse nephron, using the microperfusion technique and the electron microprobe analysis to determine the ionic composition of the collected tubular fluid. Simultaneously, the transepithelial potential difference (PDte) and the transepithelial resistance (Rte) were recorded. Prior to the flux measurements cTAL segments were perfused for one hour. During this equilibration period PDte decreased significantly from +19.9±1.6 to +14.9±1.l mV and Rte increased from 30.6±3.5 Ωcm2 to 38.8±2.4 Ωcm2 (n=7), reflecting a decline in NaCl transport. After ADH was added to the bath solution at 10−10 mol.l−1, PDte increased from +14.4±1.1 to +18.0±1.5 mV, accompanied by a rise in JNa and JCl from 205±11 to 273±19 and from 216±12 to 283±21 pmol.min−1.mm−1 (n=7), respectively. JCa and JMg also increased from 0.81±0.07 to 1.50±0.12 and from 0.43±0.11 to 0.76±0.08 pmol.min−1.mm−1 (n=7), respectively. All these effects were fully reversible after withdrawal of the hormone. In conclusion our data indicate that ADH stimulates divalent cation transport and NaCl transport in the cortical thick ascending limb of Henle's loop of the mouse.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00373010
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of glucagon on Na+, Cl−, K+, Mg2+ and Ca2+ transports in cortical and medullary thick ascending limbs of mouse kidney (1989)
    Springer
    Pflügers Archiv 414 (1989), S. 640-646 
    Details
    ISSN: 1432-2013
    Keywords: Glucagon ; Transepithelial ion net fluxes ; Na+, Cl−, K+, Ca2+, Mg2+ transport ; Electron microprobe ; Mouse kidney ; In vitro microperfusion ; Cortical and medullary thick ascending limb of Henle's loop ; In vivo micropuncture study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of glucagon on transepithelial Na+, Cl−, K+, Ca2+ and Mg2+ net fluxes were investigated in isolated perfused cortical (cTAL) and medullary (mTAL) thick ascending limbs of Henle's loop of the mouse nephron. Transepithelial ion net fluxes (J Na +,J Cl −,J K +,J Ca 2+,J Mg 2+) were determined by electron probe analysis of the collected tubular fluid. Simultaneously the transepithelial voltage (PDte) and the transepithelial resistance (R te) were recorded. In cTAL-segments (n=8), glucagon (1.2×10−8 mol · l−1) stimulated significantly the reabsorption of Na+, Cl−, Ca2+ and Mg2+∶J Na + increased from 204±20 to 228±23 pmol · min−1 · mm−1,J Cl − from 203±18 to 234±21 pmol · min−1 · mm−1,J Ca 2+ from 0.52±0.13 to 1.34±0.30 pmol · min−1 · mm−1 andJ Mg 2+ from 0.51±0.08 to 0.84±0.08 pmol · min−1 · mm−1.J K+ remained unchanged: 3.2±1.3 versus 4.0±1.9 pmol · min−1 · mm−1. Neither PDte (16.3±1.5 versus 15.9±1.4 mV) norR te (22.5±3.0 versus 20.3±2.6 Ωcm2) were changed significantly by glucagon. However, in the post-experimental periods a significant decrease in PDte and increase inR te were noted. In mTAL-segments (n=9), Mg2+ and Ca2+ transports were close to zero and glucagon elicited no significant effect. The reabsorptions of Na+ and Cl−, however, were strongly stimulated:J Na + increased from 153±17 to 226±30 pmol · min−1 · mm−1 andJ Cl − from 151±23 to 243±30 pmol · min−1 · mm−1. The rise in NaCl transport was accompanied by an increase in PDte from 10.3±1.1 to 12.3±1.2 mV and a decrease inR te from 19.1±2.7 to 17.8±2.0 Ωcm2. No net K+ movement was detectable either in the absence or in the presence of glucagon. A micropuncture study carried out in hormone-deprived rats indicated that glucagon stimulates Na+, Cl−, K+, Mg2+ and Ca2+ reabsorptions in the loop of Henle. In conclusion our data demonstrate that glucagon stimulates NaCl reabsorption in the mTAL segment and to a lesser extent in the cTAL segment whereas it stimulates Ca2+ and Mg2+ reabsorptions only in the cortical part of the thick ascending limb of the mouse nephron. These data are in good agreement with, and extend, those obtained in vivo on the rat with the hormone-deprived model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00582129
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  • 6
    Electronic Resource
    Electronic Resource
    Glucagon inhibits water and NaCl transports in the proximal convoluted tubule of the rat kidney (1991)
    Springer
    Pflügers Archiv 419 (1991), S. 472-477 
    Details
    ISSN: 1432-2013
    Keywords: Glucagon ; Transepithelial ion net fluxes ; Water, Na+, Cl−, K+, Mg2+, Ca2+, transport ; Electron microprobe ; Rat kidney ; In vivo micropuncture study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of glucagon on water and electrolyte transport in the kidney were investigated on hormone-deprived rats, i.e. thyroparathyroidectomized diabetes insipidus Brattleboro rats infused with somatostatin. Glucagon consistently inhibited the reabsorption of water and Na+, Cl−, K+ and Ca2+ along the proximal tubule accessible to micropuncture, leaving the reabsorption of inorganic phosphate (Pi) untouched. In the loop, besides its previously described stimulatory effects on Na+, Cl−, K+, Ca2+ and Mg2+ reabsorption, glucagon strongly inhibited Pi reabsorption, very probably in the proximal straight tubule. These effects resulted in a significant phosphaturia and considerable reductions of Mg2+ and Ca2+ excretions. The effects of glucagon at both the whole kidney and the nephron levels are very similar to those previously described for calcitonin. In the absence of an adenylate cyclase system sensitive to glucagon and calcitonin in the rat proximal tubule, and from the analogy of their physiological effects with those elicited by parathyroid hormone, it is suggested that glucagon and calcitonin exert their inhibitory effects on Na and Pi reabsorption in the proximal tubule through another pathway, which could be the phosphoinositide regulatory cascade.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00370791
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  • 7
    Electronic Resource
    Electronic Resource
    Influence of extracellular fluid volume expansion on magnesium, calcium and phosphate handling along the rat nephron (1976)
    Springer
    Pflügers Archiv 365 (1976), S. 203-211 
    Details
    ISSN: 1432-2013
    Keywords: Extracellular fluid volume expansion ; Mg, Ca and Pi renal handling ; Electron microprobe analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Renal tubular handling of P, Ca, Mg and Na was studied in the rat both before and during mild hypertonic NaCl loading (ECVE), using micropuncture and clearance techniques and electron microprobe analysis. Micropuncture was performed at the late proximal and early distal tubule sites. ECVE significantly increased the urinary output of all four elements. In the case of Mg, the increase was relatively small and dependend of reabsorption all along the entire length of the nephron. For Ca, it depended on the inhibition of proximal reabsorption, partially compensated by increased reabsorption along the loop. For P, it depended on proximal inhibition, no important net phosphate movement occuring in the loop during both periods. Ca reabsorption was highly correlated to that of sodium along the proximal tubule and Henle's loop. This was not the case for Mg and P. In the loop, Ca and Mg reabsorption were closely related to the load delivered at the beginning of the structure. These observations are compatible with the view that tubular reabsorption of Ca and Mg is concentration rather than Tm limited, and that reabsorption of Ca, unlike that of Mg, is linked to the movements of sodium. Following ECVE, the difference between early distal and urinary deliveries increased significantly for Ca and P, but not for Mg. For phosphate, this difference accounted for by 45% of the delivery at the early distal tubule site, at variance with microinjection data obtained in the rat under similar salt loading conditions, which indicated that 17% only of the phosphate distal delivery were reabsorbed along the terminal segments. This discrepancy is discussed in terms of nephron functional heterogeneity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01067020
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