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  • Plasma-Renin-Konzentration beim Menschen  (1)
  • Potassium depolarization  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Pflügers Archiv 411 (1988), S. 252-258 
    ISSN: 1432-2013
    Keywords: Potassium depolarization ; Chloride conductance ; Ion fluxes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of partial replacement of bathing solution sodium by potassium on potential difference, conductance and ion transport of canine tracheal epithelium were studied in Ussing chambers. Whereas up to 100 mmol/l mucosal K+ had no effect, raised serosal [K+] induced a concentration dependent decrease in transepithelial potential difference and increase in conductance. When serosal K+ was 100 mmol/l, the potential difference fell 30 mV to 1.1±1.0 mV and conductance rose 4.5 mS/cm2 to 6.6 ±0.9 mS/cm2. Seventy-five percent of the K+ induced conductance required Cl− (120 mmol/l) in the luminal bathing solution. Unidirectional Cl− fluxes were increased by raised serosal K+ but14C-mannitol permeability was unchanged. The increased unidirectional Cl− flux induced by high K+ exposure was inhibited by luminal exposure to diphenylamine-2-carboxylic acid (DPC) or other chloride channel blockers, but was not inhibited by loop diuretics. These results suggest that in the presence of 100 mmol/l serosal K+ the transcellular chloride conductance of tracheal epithelium was increased. Increased chloride conductance of the apical cell membrane contributed to the raised transcellular permeability, but the route across the basolateral cell membrane was not identified.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1440
    Keywords: Plasma renin concentration in humans ; micromethod for plasma renin ; sheep angiotensinogen ; plasma renin concentration in babies ; Plasma-Renin-Konzentration beim Menschen ; Mikromethode zur Plasma-Renin-Bestimmung ; Schaf-Angiotensinogen ; Plasma-Renin-Konzentration bei Säuglingen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es wird ein einfaches, empfindliches Verfahren zur Bestimmung der Plasma-Renin-Konzentration beim Menschen beshrieben, das auf der von Boucheret al. [Canad. J. Physiol. Pharmacol.45, 881 (1967)] angegebenen Methode beruht. 1,0 ml Plasma, 1.0 ml Dowex 50WX2-(NH4)+ und Schaf-Angiotensinogen im Überschuß — gelöst in 2,0 ml EDTA- und NaN2-haltigem Trisphosphatpuffer — werden 15 Std bei 37°C inkubiert. Die Umsetzung des Human-Renins mit dem Schafsubstrat folgte einer Michaelis-Menten-Kinetik und ergab eine 1,5–2fach höhere Angiotensinausbeute als bei der entsprechenden Reaktion mit homologem Substrat. Die Präzision bei Doppelbestimmungen betrug 7,0±6,2% des kleineren Wertes. Die Angiotensin II-Wiederfindungsrate war in dem untersuchten Bereich von 25–200 ng linear und betrug im Mittel 84,4±10%. Bei gesunden Erwachsenen unter freier Kochsalzzufuhr wurde folgender Normbereich ermittelt: 0,9±0,6 ng Angiotensin/ml/h in Ruhe bzw. 2,1±1,0 ng/ml/h nach aktiver Orthostase. Bei gesunden Säuglingen betrug die Plasma-Renin-Konzentration unter ambulanten Bedingungen 3,4±1,6 ng/ml/h und war damit signifikant höher als die Normalwerte der Erwachsenen in Ruhe und nach Orthostase (P〈0,001).
    Notes: Summary A simple, sensitive method for determination of human plasma renin concentration is described. The procedure is based on the method of Boucheret al. [Canad. J. Physiol. Pharmacol.45, 881 (1967)]. One ml plasma and 1.0 ml Dowex 50WX2-(NH4)+ are incubated for 15 hours at 37°C with 150 mg sheep angiotensinogen in 2.0 ml trisphosphate buffer containing EDTA and NaN3. The reaction of the human renin with the sheep angiotensinogen followed the Michaelis-Menten kinetics and yielded a 1.5 to 2 fold amount of angiotensin compared to the reaction with homologous substrate; the recovery of angiotensin was 84.4±10% being linear in the range studied (25–200 ng angiotensin II). The normal values of 22 healthy adults during a free diet were 0.9±0.6 ng angiotensin/ml/h in recumbent and 2.1±1.0 ng/ml/h in upright posture. During ambulatory conditions the plasma renin concentration in healthy babies was 3.4±1.6 ng/ml/h. These values were significantly higher than those in adults in recumbent and upright posture (p〈0.001).
    Type of Medium: Electronic Resource
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