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  • 1
    ISSN: 1432-2013
    Keywords: Diuretics ; Stereospecifity ; Micropuncture ; Renal blood flow ; Transport mechanisms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The renal actions of the optically active isomers of the new diuretic drug ozolinone were studied by clearance, flowmeter and micropuncture techniques in rats. The levorotatory, but not the dextrorotatory isomer of ozolinone increased urine flow, urinary sodium and chloride excretion and enhanced sodium and chloride concentrations in early distal tubular fluid as checked by in situ microperfusion of Henle's loops. This indicates stereospecifity of the drug's diuretic action. However, both isomers of ozolinone equally inhibited maximal tubular secretion of paraaminohippurate and increased renal blood flow as measured by an electromagnetic flowmeter. Thus, the different renal target structures of ozolinone differ markedly with respect to stereoselectivity.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2013
    Keywords: Diuretics ; Stereospecificity ; Transport mechanism ; Loop of Henle ; Micropuncture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of the non-diuretic dextrorotatory isomer of ozolinone on furosemide-induced diuresis was studied by means of clearance and micropuncture techniques in rats. After intravenous injection,d-ozolinone antagonized the furosemide-induced increase in renal fluid and electrolyte excretion in a dose-related manner. Microperfusion experiments of Henle's loop in vivo revealed thatd-ozolinone did not interfere with the action of furosemide at this tubular site. However,d-ozolinone markedly decreased the furosemide to inulin clearance ratio, presumably as a consequence of inhibition of furosemide secretion into the proximal tubules. It is assumed that, in consequence of a high affinity for the proximal organic acid transport system,d-ozolinone depresses proximal tubular furosemide secretion and prevents transfer of this diuretic to the tubular fluid. Thus, under the influence ofd-ozolinone, furosemide cannot reach the loop of Henle in sufficient amounts and its diuretic effect is blocked.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 261 (1968), S. 299-313 
    ISSN: 1432-1912
    Keywords: Ca-ions ; Potassium Excretion ; Water Diuresis ; Antidiuresis ; Tissue Osmolality ; Ca-Ionen ; K-Ausscheidung ; Wasserdiurese ; Antidiurese ; Gewebsosmolalität
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung 1. Nach Infusion oder Injektion von CaCl2 steigt bei Hunden sowohl die Na- als auch die K-Ausscheidung an. Ihr Verhältnis zueinander bleibt dabei konstant. Nach Acetazolamid oder Hg-Diuretica wird das Verhältnis Na-/K-Exkretion charakteristisch verändert. Zusätzliche Gabe von CaCl2 beeinflußt das so veränderte Verhältnis nicht. Daraus wird geschlossen, daß Ca-Ionen die K-Ausscheidung nicht spezifisch beeinflussen. 2. Ca-Ionen vermindern in Wasserdiurese die $$C_{H_2 O} $$ und in Antidiurese die $$T_{{}^cH_2 O} $$ . 3. Sowohl nach kurzdauernder Hypercalcämie von 20 min als auch nach Anhebung des Plasmacalciumspiegels für mehr als 1 Woche ist die Osmolalität und die Na-Konzentration des Gewebes von Nierenmark und -papille von Hunden im Durstzustand erheblich vermindert. Der Wassergehalt und die K-Konzentration sind nicht beeinflußt. 4. Die Befunde machen die Annahme wahrscheinlich, daß die in Clearance-Versuchen beobachtete Diurese nach Gabe von Ca-Ionen mindestens zum Teil im aufsteigenden Ast der Henleschen Schleife hervorgerufen wird.
    Notes: Summary 1. Infusions or injections of CaCl2 into dogs enhance the excretion of both, sodium and potassium. However, the relation of Na to K excretion is not altered. Acetazolamide or mercurial diuretics change this relation in a characteristic manner. Additional administration of CaCl2 has no further effect on the newly established relationship. It is assumed that Ca-ions have no specific influence on potassium excretion. 2. Ca-ions decrease both, $$C_{H_2 O} $$ in water diuresis and $$T_{{}^cH_2 O} $$ in in antidiuresis. 3. The osmolality and the concentration of sodium in the tissue of the medulla and papilla was decreased when acute hypercalcaemia was induced by the infusion of a CaCl2 solution into one renal artery for 20 min and also when the plasma calcium concentration had been increased for at least one week. Water content and potassium concentration were unchanged. 4. These results are compatible with the hypothesis that the diuresis observed in clearance experiments following infusions of calcium salts is provoked at least to some extent in the ascending limb of the loop of Henle.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 304 (1978), S. 283-287 
    ISSN: 1432-1912
    Keywords: Diuretics ; Tubular electrolyte reabsorption ; Glomerular filtration rate ; Renal blood flow ; Tubular PAH secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The renal action of 3-methyl-4-oxo-5-piperidino-thiazolidine-2-ylidine (ozolinone), a metabolite of the diuretic etozoline (Elkapin), was studied in anaesthetized dogs after i.v. injection and compared with the renal effects of furosemide. The diuretic action of ozolinone was rapid in onset and of short duration. Thesmallest effective i.v. dose was 1 mg\kg−1. Maximal diuretic capacity was reached at 50 mg\kg−1 i.v. Fractional tubular sodium reabsorption was depressed to 67% at maximal effective doses. Ozolinone had similar renal actions to those of furosemide. Like furosemide, ozolinone increased renal blood flow, slightly decreased glomerular filtration rate, depressed tubular chloride reabsorption more than sodium reabsorption, increased potassium excretion, lowered the pH of urine, decreased urinary osmolarity towards isotonicity and depressed tubular PAH secretion. As regards the effective doses and the maximal changes of tubular sodium excretion, ozolinone was somewhat less potent than furosemide.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 304 (1978), S. 289-296 
    ISSN: 1432-1912
    Keywords: Diuretics ; Clearance technique ; Micropuncture ; Tubular function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of ozolinone (3-methyl-4-oxo-5-piperidino-thiazolidine-2-ylidene) on renal tubular and glomerular functions were studied in rats using clearance and micropuncture techniques. Ozolinone (50 mg·kg−1 i.v., 50 mg·kg−1·h−1i.v.) markedly increased urine volume, urinary sodium excreation and — to a minor extent — also urinary potassium excretion. Fractional tubular sodium reabsorption fell by 14%. Renal blood flow, as measured by an electromagnetic flowmeter, increased considerably during the administration of the drug. Despite the fact that ozolinone increased intratubular hydrostatic pressure, whole kidney as well as single nephron GFR—measured at different tubular sites — remained constant due to an increase in glomerular capillary pressure (stopped flow measurements, servo nulling technique). The diuretic decreased intrinsic reabsorptive capacity of the proximal tubular epithelium as measured with the shrinking drop technique of Gertz, but had no clearcut effects on proximal fractional reabsorption. Fractional reabsorption was evaluated not only from free flow endproximal tubular fluid to plasma inulin measurements but also from transit time and half time of reabsorption (shrinking drop technique). An impressive depression of fluid, sodium and potassium reabsorption occurred in the loops of Henle after ozolinone. No further inhibition of fluid and sodium reabsorption in the distal convoluted tubules could be detected after the drug using a free flow recollection technique. Concerning the tubular site of renal action there is a striking similarity between ozolinone and the strong acting diuretic furosemide, although the chemical structures of these drugs are quite different. Differences between the two drugs exist concerning the endproximal tubular chloride concentration, which was decreased by furosemide but was not affected by ozolinone. This points to different effects of the drugs on proximal tubular bicarbonate reabsorption.
    Type of Medium: Electronic Resource
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