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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 56 (1978), S. 131-138 
    ISSN: 1432-1440
    Keywords: Sympathische Aktivität ; Plasma Noradrenalin ; Adrenalin ; Dopamin ; Gefäßreaktivität ; Uptake Aktivität ; Genetische Hypertonie ; Sympathetic activity ; Plasma noradrenaline ; Adrenaline ; Dopamine ; Vascular reactivity ; Uptake activity ; Spontaneous hypertension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Differences in sympathetic vascular tone between Wistar Kyoto rats (WKR) and stroke prone spontaneously hypertensive rats (spSHR) were determined by comparing the following parameters: sympathetic activity was evaluated by determinations of plasma catecholamines (noradrenaline, adrenaline, dopamine) combined with the measurement of the neuronal and extraneuronal uptake of noradrenaline using an isolated rat heart preparation. The responsiveness of vascular smooth muscle to vasopressor agents was tested in the isolated perfused hindlimb preparation. At the age of 5, 12, 15, and 28 weeks sympathetic nervous activity was significantly higher in spSHR than in WKR since plasma noradrenaline was elevated by almost 50% in the presence of an unaltered activity of the uptake mechanisms. The responsiveness of vascular smooth muscle to noradrenaline was markedly enhanced in spSHR. Besides increased maximal vasoconstriction in response to BaCl2 (20 mmol/l) after potassium chloride depolarization or supramaximal doses of noradrenaline (10−3 mol/l), a supersensitivity of vascular smooth muscle to noradrenaline could also be detected in spSHR (age 5 weeks). The threshold dose and the ED50 were reduced by 25% in spSHR in response to noradrenaline infusions. No changes in threshold or ED50 were found in response to potassium chloride depolarization. The stimulated sympathetic activity in spSHR and the increased responsiveness of resistance vessels to noradrenaline, both contribute to the rise in sympathetic vascular tone. The finding of an increased sympathetic vascular tone in very early stages of hypertension suggest that this factor, producing a primary increase in total peripheral resistance underlies the development of high blood pressure in spSHR.
    Notes: Zusammenfassung Unterschiede des sympathischen Gefäßtonus zwischen spontan hypertonen Ratten (spSHR) und Wistar Kyoto Ratten (WKR) wurden an Hand folgender Größen erfaßt: Die sympathische Aktivität wurde ermittelt durch die Bestimmung der Plasmakatecholamine (Noradrenalin, Adrenalin und Dopamin) bei gleichzeitiger Messung der neuronalen und extraneuronalen Wiederaufnahme von Noradrenalin im isolierten Präparat (Langendorff Herz). Die Ansprechbarkeit glatter Gefäßmuskulatur auf vasopressorische Substanzen wurde in der isoliert perfundierten Hinterextremität der Ratte gemessen. Die sympathische Aktivität war bei spSHR im Alter von 5, 12, 15 und 28 Wochen gesteigert, da die Konzentration von Noradrenalin im Plasma um 50% bei unveränderter neuronaler und extraneuronaler Wiederaufnahme erhöht war. Die Ansprechbarkeit der glatten Gefäßmuskulatur gegenüber Noradrenalin war bei spSHR verstärkt. Neben einer stärkeren maximalen Vasokonstriktion nach supramaximalen Dosen von Noradrenalin (10−3 mol/l) oder BaCl2 (20 mmol/l) fand sich eine spezifische Überempfindlichkeit der einzelnen glatten Muskelzelle gegenüber Noradrenalin bei 5 Wochen alten spontan hypertonen Ratten. Während nach Kaliumdepolarisation keine Unterschiede in der Schwellendosis oder der ED50 auftraten, waren diese bei spSHR für die Noradrenalin-induzierten Widerstandserhöhungen um 25% vermindert. Die stimulierte sympathische Aktivität sowie die erhöhte Ansprechbarkeit der Widerstandsgefäße gegenüber Noradrenalin bei spSHR sind Ursache des gesteigerten sympathischen Gefäßtonus, der über eine Erhöhung des peripheren Widerstandes die Entwicklung des hohen Blutdrucks bei der genetischen Hypertonie der Ratte verursacht.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 313 (1980), S. 155-157 
    ISSN: 1432-1912
    Keywords: Spontaneosly hypertensive rats ; Urinary kallikrein ; Sympathetic activity ; 6-Hydroxydopamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Urinary kallikrein excretion was studied in young, stroke-prone, spontaneously hypertensive rats (spSHR). Seven-week-old spSHR were found to excrete more kallikrein into the urine than normotensive Wistar Kyoto control rats (WKR). “Chemical sympathectomy”, induced by 6-hydroxydopamine (6-OHDA) immediately after birth, resulted in normotensive blood-pressure levels and in a reduction of kallikrein in spSHR. In normotensive WKR, blood pressure and urinary kallikrein excretion were only slightly diminished by 6-OHDA. The results suggest a relationship between sympathetic activity and kallikrein excretion, being especially pronounced in spSHR, which have an elevated sympathetic activity.
    Type of Medium: Electronic Resource
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