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  • 1
    Electronic Resource
    Electronic Resource
    A study of the applicability of the electron microprobe to a quantitative analysis of K and Na in single human red blood cells
    Amsterdam : Elsevier
    FEBS Letters 41 (1974), S. 81-84 
    Details
    ISSN: 0014-5793
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0014-5793(74)80959-2
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  • 2
    Electronic Resource
    Electronic Resource
    Renal function and concentrating ability in a desert rodent: The gundi(Ctenodactylus vali) (1981)
    Springer
    Pflügers Archiv 390 (1981), S. 138-144 
    Details
    ISSN: 1432-2013
    Keywords: Desert rodents ; Renal concentrating ability ; Medullary recycling of urea ; Renal vascular organization ; Structure-function relationship
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Clearance and cortical micropuncture experiments were carried out on non diuretic gundis. In this species, the kidney has a long and well developed papilla but, unlike other desert rodents, the vascular organization of the outer medulla is very simple. After withdrawal of water supply for either 24 h or 3 days before the experiments, the urine osmolality was only 1,361±57,n=9, before and 1,136±89 mosmol ·kg−1 during anesthesia. The GFR per 100 g B. W. (0.450 ml ·min−1) is lower than in the rat studied under similar conditions. With regard to electrolytes the tubular handling of Na, Ca, K and Mg is similar to that observed for another desert rodent, psammomys obesus. For P, massive reabsorption (more than 30% of the filtered load) takes place along the distal convoluted tubule. The relatively poor concentrating ability of the gundi's kidney is not due to a lack of medullary recycling of urea since a net addition of urea to short loops of Henle is observed in this species. Physiological and morphological observations concerning the gundi and other desert rodent species suggest that the vascular bundle development in the outer medulla might affect the renal response to water deprivation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00590196
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  • 3
    Electronic Resource
    Electronic Resource
    Simultaneous Mg, Ca, P, K and Cl analysis in rat tubular fluid (1974)
    Springer
    Pflügers Archiv 346 (1974), S. 189-204 
    Details
    ISSN: 1432-2013
    Keywords: Kidney Micropuncture ; Mg, Ca,P i Excretion ; Electron Probe Analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary P i, Ca, Mg, Na, Cl and K handlings by the rat kidney tubules were analysed before, during, and after an acute phosphate plasma loading, using the tubular fluid recollection technique and electron microprobe analysis. As compared to the control period, hyperphosphatemia resulted in: a) a drop in plasma ultrafiltrate calcium concentration; b) some increase in GFR; c) a 20% decrease in (TF/P) Inulin in both late proximal and early distal fluid samples; d) fractional proximal reabsorptions of Na, Cl and K were reduced to about the same proportion. All these effects partly reversed after stopping the phosphate perfusion; e) as a mean value, both relative and even (to a lesser extent) absolute proximal phosphate reabsorption decreased during the loading and the recovery periods; f) the observed change in overall kidney phosphate reabsorption as a function of the filtered load was entirely accounted for by a change in the reabsorption taking place along the terminal segments; g) (TF/P f ) mean value for calcium in late proximal samples dropped to 0.78 during the loading period and to 0.83 during the third period; h) (TF/P f ) mean value for magnesium was 1.66 during the control period, and only 1.12 during the last period; accordingly fractional proximal Mg reabsorption increased from 13 (control) to 35% (recovery period); this delayed effect of hyperphosphatemia on proximal Mg handling accounted for the reduction in urinary Mg output noted during the last period. The possible role of hyperphosphatemia, extracellular expansion, hypocalcemia and maximal PTH release is discussed in order to explain these different observations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00595706
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  • 4
    Electronic Resource
    Electronic Resource
    Renal phosphate transport: Inhomogeneity of local proximal transport rates and sodium dependence (1975)
    Springer
    Pflügers Archiv 356 (1975), S. 287-297 
    Details
    ISSN: 1432-2013
    Keywords: Renal Tubule ; Phosphate Transport ; Sodium Dependence ; Micropuncture ; Microperfusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The standing droplet method has been used in combination with the peritubular perfusion of blood capillaries to determine the build up of transtubular concentration differences of phosphate (P i ) in the renal proximal convoluted tubule of parathyroidectomized rats. Electron probe analysis was used to estimate P i . At zero time both the intraluminal and the contraluminal P i concentration was 2 mM. The time dependent decrease of the intraluminal P i concentration was approximately 4 times faster in the early than in the late proximal convoluted tubule. After 45 sec an intraluminal steady state concentration of 0.20 mM P i was achieved in the early part. In the late part the intraluminal P i concentration approached a steady state value of 0.54 mM at 120 sec. When sodium free solutions were used the intraluminal P i concentration increased to 2.22 mM in the earlier and to 2.76 mM in the late part. The data indicate that in the proximal convoluted tubule 1. The rate of phosphate reabsorption is greater in the early part than in the later part, and 2. phosphate reabsorption might occur as co-transport with Na+ ions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00580003
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  • 5
    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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  • 6
    Electronic Resource
    Electronic Resource
    Effects of human calcitonin on water and electrolyte movements in rat juxtamedullary nephrons: inhibition of medullary K recycling (1986)
    Springer
    Pflügers Archiv 406 (1986), S. 502-508 
    Details
    ISSN: 1432-2013
    Keywords: Calcitonin ; Urinary concentrating mechanism ; Magnesium and calcium ; Electron probe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of synthetic human calcitonin (HCT) on water and electrolyte deliveries to the thin limbs of Henle's loop of juxtamedullary nephrons were investigated by micropuncture in the rat. To avoid undesirable interference with exogenous calcitonin, experiments were performed in hormone-deprived rats with reduced circulating calcitonin, antidiuretic hormone, parathyroid hormone and glucagon, all four of which stimulate the adenylate-cyclase activity in the thick ascending limb and the distal tubule. Administration of HCT (1.0 mU/min·100 g body wt) to such rats significantly reduced the urinary fractional excretion rate of water, Mg, Ca and K. At the tip of the long-looped nephrons, the fractional delivery of water diminished in the presence of HCT, although the glomerular filtration rate of these nephrons was unaltered. Simultaneously, the loop fluid osmolality rose significantly. HCT, however, did not alter the fraction of total filtered solutes remaining in the thin limbs, nor the NaCl fractional delivery. As previously observed in this laboratory with dDAVP, the reduced fractional delivery of water at the hairpin turn was accompanied by a decrease in Mg and Ca deliveries in rats given HCT, indicating that the handling of these two ions along the descending limb may be linked in part to the water movements in this nephron segment. The fractional deliveries of K at the hairpin turn and in urine were significantly correlated, and both decreased in the presence of HCT. Since, as shown previously, HCT reduces the net addition of K along the superfical distal tubule, it is concluded that calcitonin inhibits the medullary recycling of K between the nephron terminal segments and the loop of Henle of juxtamedullary nephrons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00583374
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  • 7
    Electronic Resource
    Electronic Resource
    Stimulation by human calcitonin of electrolyte transport in distal tubules of rat kidney (1983)
    Springer
    Pflügers Archiv 399 (1983), S. 111-118 
    Details
    ISSN: 1432-2013
    Keywords: Calcitonin ; Distal tubule ; Micropuncture ; Electron-probe ; Brattleboro rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of human calcitonin (HCT) on the distal tubule were investigated by micropuncture in hormone-deprived rats, i.e. in the absence of parathyroid hormone, antidiuretic hormone and glucagon, which might have masked these effects. Two groups of rats were studied: hormone-deprived and hormone-deprived+HCT, infused at 1.0 mU/min\100 g b.w. In the urine, HCT markedly reduced Ca and Mg excretion whereas excretion of water, Na and K was not significantly affected. Along the distal tubule, HCT strongly enhanced Na, Cl, Mg, Ca and total solute reabsorption, decreased K secretion but did not alter water or phosphate transport. It is concluded that HCT stimulated Na, Cl, Ca and Mg reabsorption. If, as suggested, HCT also stimulated the reabsorptive component of K transport, the hormone should therefore elicit the same physiological effects in the distal tubule and the thick ascending limb.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00663905
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  • 8
    Electronic Resource
    Electronic Resource
    Simultaneous Mg, Ca, P, K, Na and Cl analysis in rat tubular fluid (1974)
    Springer
    Pflügers Archiv 346 (1974), S. 171-188 
    Details
    ISSN: 1432-2013
    Keywords: Micropuncture Experiments ; Ca, Mg, Phosphate Excretion ; Acute Ca Loading ; Electron Probe Analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Ca, Mg, Phosphate, Na, K and Cl handlings by the tubules of the rat kidney were analysed before, during and after acute Ca plasma loading by using the micropuncture recollection technique associated to electron probe micro-analysis of tubular fluid composition.3H-inulin was used as glomerular indicator. Intravenous CaCl2 perfusion increased total plasma Ca from 2.46 up to 3.66 mM and ultrafilterable plasma Ca from 1.49 up to 1.73 mM. From late proximal and early distal micropuncture data, it was observed that, during hypercalcemia: 1. along PCT, (TF/P f ) Ca rose above unity (1.21±0.07;p〈0.01); fractional Ca reabsorption was therefore reduced, but absolute reabsorption remained unchanged; 2. calcium reabsorption was increased in the loop segments, probably due to the increased delivery; 3. Ca reabsorption by the terminal segments apparently stopped, since Ca delivery to the superficial DCT and urinary Ca output were found equal; 4. fractional Mg reabsorption was not modified in PCT (20% of the filtered load), but it was inhibited in the loop, suggesting competition with Ca ions for transport; 5. the resulting increase in distal Mg delivery together with suppression of Mg reabsorption by the terminal segments accounted for a large urinary Mg output. All these effects reversed after stopping CaCl2 perfusion. During the recovery period, 6. GFR dropped by 25%, which reduced water and solute excretion; 7. a delayed renal response to PTH suppression by hypercalcemia was suggested by a relatively sustained Ca excretion together with an acute drop in phosphate output; 8. this drop in phosphate excretion resulted from an increased reabsorption along the terminal segments; 9. Na, K and Cl tubular handlings were not greatly affected by the induced hypercalcemia, and no competition between Ca and Na ions for reabsorption could be observed in these experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00595705
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  • 9
    Electronic Resource
    Electronic Resource
    3H-Inulin and electrolyte concentrations in Bowman's capsule in rat kidney (1975)
    Springer
    Pflügers Archiv 354 (1975), S. 117-131 
    Details
    ISSN: 1432-2013
    Keywords: Kidney Micropuncture ; Bowman's Capsule ; Na, Cl, K, P, Ca, Mg Concentrations ; Ultrafiltration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Micropuncture experiments were performed on Bowman's capsules in male and female non-diuretic Munich rats. 55 samples were collected and analysed for Na, Cl, K, Ca, P, Mg and3H-inulin contents. Their electrolyte concentrations were compared to the corresponding concentrations obtained from plasma artificial ultrafiltrates. Compared to normal Wistar rats, our Munich rats had several special characteristics: high arterial pressure (115–155 mm Hg), high concentrating ability (π=2684 mOsm/l) and high NaCl reabsorption capacity. Whole kidney GFR was low in males (0.361 ml/min/kidney/100 g B.W.). 3H-Inulin concentration was the same in plasma and glomerular ultrafiltrates (GF). The corresponding ratio (GF/P) In=1.03±0.01 (N=55) confirmed the lack of sieving effect for inulin. GF electrolyte concentrations were, for Na, Cl, K, Ca, P, Mg respectively 139±2, 124±1, 3.89±0.23, 1.31±0.05, 1.46±0.07 and 0.52±0.04 mM/l (N=23)1 in females and 141±2, 120±2, 3.84±0.07, 1.31±0.03, 1.78±0.05 and 0.48±0.01 mM/l (N=32) in males. Comparison of ultrafiltration trough a cuprophan membrane and glomerular ultrafiltration led to the following conclusions: For Na, Cl and P artificial and glomerular ultrafiltration produced identical results. On the other hand, for Ca and to a lesser extent for Mg and K ions, artificial ultrafiltration did not accurately reflect the true glomerular ultrafiltrate composition. The reasons for these differences are discussed below.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00579943
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  • 10
    Electronic Resource
    Electronic Resource
    Simultaneous Mg, Ca, P, K, Na and Cl analysis in rat tubular fluid (1973)
    Springer
    Pflügers Archiv 340 (1973), S. 197-210 
    Details
    ISSN: 1432-2013
    Keywords: Micropuncture Experiments ; Mg, Ca, Phosphate Excretion ; Acute Mg Loading ; Electron Probe Analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The micropuncture recollection technique was used for further analysis of Mg, Ca, P, Na, Cl and K tubular handling during and after acute magnesium plasma loading in the rat. The concentrations of these different ion species in late proximal and early distal fluid samples, ureteral urine and plasma ultrafiltrates were measured using electron probe microanalysis.3H-inulin was used as glomerular indicator. The results indicate that 1, late proximal (TF/Pf)Mg/In values remained proportional to the filtered load (about 80%); 2. part of the filtered Mg was reabsorbed in the loop of Henle by an active and saturable transport mechanism; 3. early distal (TF/Pf)Mg/In values during and after Mg loading were below the corresponding (U/Pf)Mg/In values; this observation might either indicate net Mg tubular excretion by the terminal nephron segments or result from the building up of a medullary Mg ion pool during the loading period; 4. acute hypermagnesemia induced transient calciuria, shown to result from decreased Ca reabsorption in the terminal segments; 5. it enhanced P reabsorption in the terminal segments; the drop in P excretion might have been mediated by decreased PTH release; 6. tubular handling of the other ion species was relatively unaffected by increasing tubular Mg loading.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00586839
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