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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 28 (1985), S. 61-66 
    ISSN: 1432-1041
    Schlagwort(e): amiloride ; kidney function ; Na+ ; K+ ; Ca++ ; Mg++ excretion ; renal amiloride clearance ; chronic renal failure ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The effect of a single oral dose of 10 mg amiloride was studied on urinary excretion of Na+, K+, Ca++ and Mg++ in healthy subjects and in patients with varying degrees of renal impairment. Amiloride produced a moderate diuresis and sodium excretion, and a slight calciuresis. Urinary excretion of potassium was significantly reduced as compared to the controls. Despite its diuretic and natriuretic effects, amiloride did not change the excretion of Mg++ as compared to the pretreatment period. When the creatinine clearance was below 50 ml/min, the net excretion of Na+ and Ca++ was drastically reduced. However, K+ retention and neutrality of Mg++ excretion were maintained down to end-stage renal disease. In the healthy volunteers the mean elimination half-life of amiloride was 20 h, and it rose to about 100 h in end-stage renal disease. This was because about 3/4 of native amiloride was eliminated through the kidney. Nonrenal elimination of amiloride was calculated to amount to only 1/4 of the total elimination. Therefore, the antikaliuretic amiloride is a valuable comedication in subjects with normal kidney function to prevent K+ and Mg++ loss. However, its use is hazardous if plasma creatinine is raised.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 46 (1994), S. 9-13 
    ISSN: 1432-1041
    Schlagwort(e): Bemetizide ; Salt excretion pattern ; Na+ ; K+ ; Cl− ; Mg2+ ; Ca+ ; chronic renal failure ; renal haemodynamics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract The effect of the thiazide diuretic, bemetizide, on the excretion of Na+, K+, Cl−, Ca2+, and Mg2+ in relation to the glomerular filtration rate (GFR) was studied in 17 subjects whose creatinine clearances ranged from 133 to 5 ml·min−1. After a 2-day fluid and salt balanced control period, 25 mg bemetizide given orally induced natriuresis and kaliuresis which lasted for 24 h and were proportional to the GFR of the patients. The ratio of bemetizide-induced K+/Na+ excretion was always 0.17 irrespective of individual GFR. In renal failure, bemetizide increased the fractional Na+ excretion from 3% to about 10%. Kaliuresis was associated with magnesiuria, whereas bemetizide-induced calciuresis was insignificant. The thiazide reversibly lowered GFR in all subjects.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Pflügers Archiv 316 (1970), S. 238-258 
    ISSN: 1432-2013
    Schlagwort(e): Human Salivary Main Duct ; Transepithelial Electrical Potential Difference ; Salivary Secretion ; Resorption of Sodium ; Secretion of Potassium ; Speicheldrüsengang des Menschen ; Transepitheliale elektrische Potentialdifferenz ; Speichelsekretion ; Natriumresorption ; Kaliumsekretion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The electrical potential difference (PD) across the main duct epithelium of the salivary glands was measured in human volunteers. In the resting gland the PD was 38±3 mV, lumen negative. After stimulation of secretion by pilocarpine the PD increased to about 100 mV (lumen negative) and returned to the resting level when secretion ceased. The same increase of PD was observed, when saliva was collected during stimulation and infused back into the duct during the resting state. From this it was concluded that pilocarpine had no direct action on the duct epithelium and that the increase of PD was caused by the changes that are known to occur in salivary electrolyte concentrations during stimulation. This conclusion was tested by perfusion of the duct with different test solutions, so that the influence of single cations and anions on the PD could be studied. With sulfate solutions it was found that the luminal surface of the epithelium behaved like a Na-electrode; a tenfold change of Na-concentration developed nearly 61 mV while K and choline did not affect the PD. Thus the luminal cellwall appears to be selectively permeable to Na. When the duct was perfused with chloride solutions the PD was found to follow a typical time course with the initial transient values yielding a slope of 61 mV and the steady state values a slope of 35 mV for a tenfold change of Na-concentration. This observation can be explained when chloride acts as a shunt ion and when the chloride concentration within the epithelium, which determines the chloride conductance, follows the luminal chloride concentration with a time delay. From the Na und K concentrations of saliva found previously during stop flow experiments and from the present PD measurements it was concluded that the human salivary main ducts, like those of the rat, actively reabsorb Na from the saliva and probably also actively secrete K into the saliva. The localization of the single active and passive transport steps with respect to the luminal and contraluminal cell side is discussed on the basis of Ussing's model for Na transport across frog skin, in favour of which new evidence can be put forward.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Pflügers Archiv 316 (1970), S. 213-237 
    ISSN: 1432-2013
    Schlagwort(e): Human Salivary Glands ; Salivary Cation Excretion ; Sodium Reabsorption ; Potassium Secretion ; Speicheldrüsen des Menschen ; Kationenausscheidung ; Natriumresorption ; Kaliumsekretion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Human saliva was collected separately from the three major salivary glands by catheterization of the main ducts and the effect of secretion rate on salivary Na and K concentrations was studied. In the resting state, with flow rates of 0.1 to 0.4 ml/min, Na concentration of submandibular and parotid saliva was 2 meq/l and K concentration ∼20 meq/l. Similar data were obtained from the resting sublingual gland. Following stimulation with pilocarpine salivary Na concentrations rose in all glands in a typical nonlinear fashion, whereas K concentrations declined and reached constant values, which were significantly greater than those of plasma. This result confirms earlier observations in the submandibular and parotid gland of human beings and of various animals and demonstrates unequivocally that the sublingual saliva in man unlike that in cat and dog is poor in Na. By means of microanalytical methods it was possible to investigate changes in cation concentrations when the salivary flow rates were less than the normal resting values; experiments were also done when salivary flow was stopped completely. In the submandibular gland Na concentration remained at 1.4 meq/l, whereas K concentrations rose to values of 74 meq/l. K concentrations, however, did not reach a plateau value even after a contact time of 15 min. These results, together with measurements of transepithelial P.D. (reported in the following paper), indicate that Na resorption and probably also K secretion, are governed by active transport mechanisms in the duct epithelium. Thus the main duct epithelium exhibits the properties which are generally taken to be essential for the upper part of the glandular duct system, which forms final saliva from primary secretion. Similar data were obtained in the upper portion of the parotid duct. In the lower portion of this duct, however, cation concentrations followed a different pattern in showing a tendency to equilibrate with plasma. Such results would be expected if there were no mechanisms for active transport in the lower portion of the main parotid duct. In order to describe the salivary Na concentration as a function of flow rate a mathematical model was developed. It is based on the assumption that primary secretion is plasmalike and that the hypotonicity of final saliva results from active resorption of sodium in the duct system in accordance with Thaysen's hypothesis. Furthermore the rate of sodium resorption is assumed to be constant and the duct wall is considered impermeable to water. Under conditions of high salivary flow rates there was a good agreement between predicted values and experimental data. This model permits the calculation of the amount of sodium that is actively reabsorbed in the salivary duct system.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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