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  • 1
    ISSN: 1432-1041
    Keywords: Benserazide ; decarboxylase inhibition ; alpha-methyldopa ; essential hypertension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In a single-blind study, the dopa-decarboxylase inhibitor benserazide (375 mg/day for 3 days and 750 mg/day for further 3 days) and a placebo were given orally in combination with individually effective doses of alpha-methyldopa (mean 1.5 g/day) to 3 hospitalized patients with essential hypertension. Alpha-methyldopa (α-MD) alone lowered blood pressure from 165/107 to 136/93 mm Hg (P〈0.05). Benserazide did not alter the hypotensive effect of α-MD, although the decarboxylation of α-MD was markedly reduced, as shown by the urinary excretion of alpha-methyldopamine (α-MDA). During administration of α-MD alone, the ratio α-MD/α-MDA in urine of the 3 patients was 8:1, 7:1 and 22:1, respectively. When benserazide 375 mg/day was added the ratio rose to 31:1, 31:1 and 35:1; the ratio was 37:1, 18:1 and 46:1 at the higher dose of inhibitor. In a double-blind crossover study the effect on blood pressure of 3 weeks of treatment with α-MD (mean 1.75 mg/day), benserazide (375 mg/day), placebo and their combinations were compared in 5 hypertensive subjects. Again, benserazide did not influence the antihypertensive action of α-MD. To study whether benserazide entered the CNS, a single oral dose of14C-benserazide of 125 mg was given to 2 patients who were to undergo diagnostic lumbar puncture. Two hours after intake of the labelled drug, when radioactivity in blood had reached a maximum, the concentration of radioactivity in spinal fluid was less than 1% of the plasma level. Thus, the antihypertensive action of α-MD was not influenced by oral doses of the decarboxylase inhibitor benserazide. The results suggest that benserazide in doses up to 750 mg/day does not affect central decarboxylation of α-MD and that this antihypertensive agent lowers blood pressure by a central action.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1440
    Keywords: Plasmakatecholamine ; Dopamin-β-Hydroxylase ; Essentielle Hypertonie ; Körperliche Belastung ; Plasma catecholamines ; Dopamine-β-hydroxylase ; Essential hypertension ; Physical exercise
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary In 8 normotensive subjects and in 8 patients with essential hypertension total catecholamine content and dopamine-β-hydroxylase (DBH) activity in plasma were measured at rest and during physical exercise. Catecholamine levels at rest were significantly higher in the hypertensive than in the normotensive persons whereas the 2 groups of subjects did not differ in DBH activity at rest. At a work load of 150 watts there was a more pronounced increase of the catecholamine concentrations and of the DBH activity in the hypertensive patients than in the normotensives. One may conclude from the data that there is an increased sympathetic nerve activity in patients with essential hypertension.
    Notes: Zusammenfassung Bei 8 Normotonikern sowie bei 8 Patienten mit essentieller Hypertonie wurden die Konzentrationen der Gesamtkatecholamine und die Aktivität der Dopamin-β-Hydroxylase (DBH) im Plasma unter Ruhebedingungen und während körperlicher Belastung gemessen. Bei den Hypertonikern waren die Ruhewerte der Katecholamine signifikant höher als bei den Normotonikern, während die DBH-Aktivität unter diesen Bedingungen bei beiden Gruppen gleich war. Bei einer Ergometerbelastung von 150 Watt stiegen die Katecholaminspiegel und die DHB-Aktivität bei den Hochdruckkranken stärker an als bei den Probanden mit normalem Blutdruck. Aus den Untersuchungsergebnissen kann man schließen, daß bei Patienten mit essentieller Hypertonie eine erhöhte Aktivität sympathischer Nerven besteht.
    Type of Medium: Electronic Resource
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