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  • Acid-Base Equilibrium  (1)
  • Atenolol  (1)
  • 1
    ISSN: 1432-1041
    Keywords: Stress ; Atenolol ; Bopindolol ; catecholamines ; hypertension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In a study in mild hypertensives, the impact of mental and physical stress on plasma epinephrine (E), norepinephrine (NE), and on their ratio (NE/E) was evaluated. The effect of twoβ-adrenoceptor blocking drugs, atenolol and bopindolol, on plasma catecholamine levels was also examined. Each stressful stimulus significantly increased the NE and E levels compared to rest. The increase was progressive from mental stress, through the handgrip test to the treadmill test. A slight decrease in the NE/E ratio was observed following mental stress and the handgrip test, while this ratio increased during the treadmill test. No significant impact of beta blocking treatment on catecholamine levels was observed under any test condition.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1439-6327
    Keywords: Local Cerebral Blood Flow ; Acid-Base Equilibrium ; Middle Cerebral Artery Occlusion ; Local O2 Pressure ; Steal Phenomenon ; Vaso-active Substances ; Lokale Gehirndurchblutung ; Säure-Basen-Haushalt ; Verschluß ; der Arteria cerebri media ; Lokaler Sauerstoffdruck ; Steal-Phänomen ; Vasoaktive Substanzen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei narkotisierten Katzen und Schweinen wurde die Arteria cerebri media einer Hemisphäre für verschieden lange Zeiten unterbunden. Sowohl im corticalen Versorgungsbereich der unterbundenen Arterie als auch in normalen, corticalen Bereichen wurden gleichzeitig Sauerstoffdruck, lokale corticale Durchblutung, Kohlendioxyddruck und Wasserstoffionenkonzentration registriert. Der arterielle Blutdruck wurde in der thorakalen Aorta gemessen. Die Änderungen der Sauerstoffdruckwerte auf der Gehirnrinde ermöglichten bei Unterbindung der Arteria cerebri media die Abgrenzung der corticalen, minderversorgten Felder. Die Durchblutung sank in diesen Bereichen unterschiedlich stark ab. Im Zentrum der Versorgungsbezirke erreichte die Durchblutung den Nullwert. Die CO2-Drucke stiegen stark an, das corticale pH wurde im minderdurchbluteten Bereich erheblich erniedrigt. Der arterielle Blutdruck reagierte bei der Unterbindung nicht signifikant. Nach kurzdauernder Ligatur und Wiedereröffnung des Gefäßes kam es zu reaktiven Hyperämien, die jedoch nach längerer Unterbindung von über 30 min Dauer nicht mehr nachzuweisen waren. Mit der reaktiven Hyperämie war ein Sauerstoffdruckanstieg über den Ausgangswert verbunden. Das corticale pH stieg jedoch in der Regel nicht mehr über den Ausgangswert an. Intravenöse Injektionen von Noradrenalin oder Papaverin zeigten im Zentrum des Ischämiebezirks keine Reaktionen, in den Randbereichen waren im Vergleich zu normalen Gehirnanteilen die Durchblutungsänderungen und die damit verbundenen Verschiebungen der übrigen Meßwerte geringer. Nach länger dauernder Unterbindung und Wiedereröffnung des Gefäßes kam es in dessen Versorgungsbereich zu erheblichen qualitativen und quantitativen Abweichungen der Reaktionen im Vergleich zum gesunden Gewebe.
    Notes: Summary In 15 cats and 12 pigs anesthetized with Nembutal, the middle cerebral artery (m. c. a.) was transiently ligated. The ligations were extended between 5 and 40 min. In the disturbed and in normal cortical regions the following values were simultaneously recorded: local cerebral blood flow with heat clearance, local cortical oxygen pressure, carbon dioxide pressure and local cortical pH. Arterial blood pressure was recorded in the thoracic aorta. The pattern of the cortical PO2-values during occlusion of the m. c. a. was an indicator for the size of the disturbed region. It could be seen that the areas supplied by the m. c. a. were different in the two species and additionally showed interindividual variations. During occlusion of the artery the local cortical Pco2 increased to maximal values of more than 300 mm Hg, the extracellular pH decreased down to 6.35 in cats and 6.7 in pigs when recorded within the centre of disturbed areas. In the normal hemisphere PCO2 and pH remained unchanged during the open-skull experiments. Arterial blood pressure remained nearly unchanged during occlusion. When the ligation was released, the blood pressure decreased in cats (in the mean: 4 mm Hg) but remained constant in pigs. After release of the ligation a reactive hyperemia in the disturbed region was observed if the occlusion lasted a few min. After long lasting ligation the reactive hyperemia was missed. The PO2, however, increased above the initial values in both cases and cortical pH remained more acid after short and long lasting ligations. The actions of intravenously injected nor-epinephrine and papaverine were different in the various parts of the disturbed hemisphere. In the surrounding of the disturbed region flow, pH, Po2 and Pco2 changed in the same direction as in normal brain tissue. In the centre of the infarcted area no reaction was observed. Intravenous injection of papaverine after release of long lasting m. c. a.-occlusions caused the local cortical cerebral blood flow to decrease in the centre of the disturbed regions when papaverin was applied but flow increased in the normal undisturbed tissue.
    Type of Medium: Electronic Resource
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