M Wiersbitzky

University of Greifswald, Greifswald, Mecklenburg-Vorpommern, Germany

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Publications (4)3.81 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: To test the hypotheses that sodium kinetics are not affected by blood pressure, salt sensitivity, salt resistance or race, and that the kinetics of sodium balance are not a first-order process. DESIGN, PARTICIPANTS AND INTERVENTIONS: Two studies were conducted. In the first, 18 normotensive and 36 hypertensive men and women were given sodium at 120 mmol/day for 6 days, followed by 10 mmol/day for 8 days, then 400 mmol/day for 8 more days. Salt sensitivity was defined as an increase in diastolic blood pressure from the 10 to the 400 mmol/day intake. Salt resistance was defined as no increase, or a decrease in diastolic blood pressure with the increased sodium intake. In the second study, 12 white and 12 black normotensive men ingested sodium at 10, 200 or 400 mmol/day in random order, each for 7 days. All urine was collected in both protocols. Metabolic ward at the University of Greifswald (Greifswald, Germany; study 1), and Clinical Research Center (Indiana University, Indianapolis, Indiana, USA; study 2). In addition to conventional statistics, a pharmacokinetic analysis was carried out to determine the elimination rate constant and half-life. In the Greifswald study, when the sodium intake was decreased, a longer half-life was determined for the salt-sensitive than the salt-resistant hypertensive subjects. The half-life for the normotensive salt-sensitive and salt-resistant subjects did not differ. When the sodium intake was decreased, a monoexponential equation fitted the data for all subjects; when the sodium intake was increased, only data for half the subjects could be fitted to the same equation. In the Indianapolis study, black race had a significant influence upon urinary sodium excretion. Furthermore, the half-life for sodium elimination was dependent upon sodium intake; namely, the greater the intake, the longer the elimination half-life. The time required to reach sodium balance may increase following salt-sensitive increases in blood pressure rather than precede them. Race influences the time required to achieve salt balance. Sodium kinetics are not a first-order process.
    Journal of Hypertension 08/1992; 10(7):663-9. · 3.81 Impact Factor
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    ABSTRACT: Pharmacokinetic studies with the arterial chemoreceptor stimulant almitrine (100 mg per os) were performed in 12 healthy volunteers and 8 patients with essential hypertension stage I in order to evaluate the suitability of the drug for physiological tests. The parent compound was determined gas-chromatographically. Almitrine was absorbed with maximal serum levels after 1.8 +/- 0.4 h in healthy volunteers and 1.5 +/- 0.3 h in patients. The elimination proceeded biexponentially with terminal half-lives from 14.6 to 43.4 h in volunteers and 12.5-45.0 h in patients. Further characteristics were large distribution volumes (16.1 +/- 4.5 ml/g in healthy volunteers, 13.9 +/- 4.7 ml/g in patients) and large interindividual variations of all pharmacokinetic parameters by a factor of 2 to 6. Significant differences between healthy individuals and patients were not observed. The drug was well tolerated. The pharmacokinetic properties of almitrine should be included into its evaluation as a test compound.
    Biomedica biochimica acta 02/1991; 50(2):183-7.
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    ABSTRACT: Healthy and normotensive men (n = 11) were hospitalized and kept under controlled fluid and sodium intake (120 mequ/d) for 5 days. Their systemic arterial blood pressures as well as heart and breathing rates were measured, and venous blood and urine samples were collected at intervals of 1-4 h. Diuresis was induced by scheduled drinking of tea (150 ml/h). Electrolytes, osmolality, and creatinine were determined in both plasma and urine samples. Aldosterone, cortisol, and vasopressin concentrations were measured only in the plasma. On the 2nd and 3rd day of the experiments the participants received orally either a placebo-pill or 100 mg almitrine bismesylate (Vectarion). Each subject was tested in a placebo- and an almitrine experiment. The subjects responded to the almitrine treatment with a suppression of the plasma aldosterone content, a transient rise of glomerular filtration rate, a natriuresis and an increase of renal concentrating ability. In the placebo-experiments, only the transient rise of filtration rate was significant. The data indicate that almitrine, by stimulating the peripheral arterial chemoreceptors, suppresses plasma aldosterone and inhibits renal proximal sodium reabsorption by so far unknown mechanisms. They also suggest that oral and intravenous almitrine administrations, respectively, might differently affect renal hemodynamics and excretory function.
    Biomedica biochimica acta 02/1990; 49(11):1155-63.
  • B Wedler, M Wiersbitzky
    Zeitschrift für ärztliche Fortbildung 02/1990; 84(10):497-501.