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  • 1
    Digitale Medien
    Digitale Medien
    Effects of endothelin on the cardiovascular system and on smooth muscle preparations in different species (1989)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 340 (1989), S. 744-751 
    Details
    ISSN: 1432-1912
    Schlagwort(e): Endothelium ; Isolated visceral, vascular and bronchial smooth muscle ; Isolated perfused vascular beds ; Isolated hearts ; Isolated atria ; Blood pressure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary (1) The actions of porcine endothelin (ET), an endothelium-derived vasoconstrictor peptide, have been investigated in several in vitro smooth and cardiac muscle preparation as well as on the blood pressure of anaesthetized rats and rabbits. (2) In isolated visceral smooth muscles (guinea pig ileum, rat colon and uterus, rabbit jejunum) ET caused a long-lasting contraction which persisted after repeated rinsing. ET did not interfere with the spontaneous phasic activity of the rabbit jejunum or with contractions evoked by histamine or carbachol. (3) ET contracted isolated blood vessels (portal vein of guinea-pig and rat). In isolated perfused organs (rabbit ear, guinea-pig lung, rat mesentery and hindpaw) ET led to a long-lasting vasoconstriction. In the isolated perfused guinea-pig lung ET caused vaso- and bronchoconstriction. (4) ET produced a long-lasting positive inotropic effect in spontaneously beating isolated guinea-pig atria. The positive inotropic action of strophanthin was augmented in the presence of ET. (5) In the isolated perfused guinea-pig and rat hearts the prominent effect of ET was a long-lasting coronary vasoconstriction. (6) Pithed rats responded to i.v. injection of ET with a long-lasting increase in blood pressure. In pentobarbitone anaesthetized rats pretreated either with atropine, with guanethidine plus atropine, or with guanethidine plus atropine plus indomethacin, the long-lasting increase in blood pressure was smaller than in pithed rats whereas the initial short-lasting decrease in blood pressure was more pronounced; in pentobarbitone anaesthetized rabbits endothelin caused bronchoconstriction, a decrease in blood pressure and a pronounced increase in central venous pressure possibly resulting from pulmonary or coronary artery constriction or a combination of both effects. (7) Neither topical nor systemic application of ET influenced the bleeding time from small rat mesenteric arteries. (8) The general effect of ET on visceral, bronchial and vascular smooth muscles was a longlasting contraction. Despite its general constrictor potency seen in isolated vascular preparations ET can cause a transient decrease in arterial blood pressure in anaesthetized rats and rabbits. The role of ET when released from vascular endothelium remains a matter of speculation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00169684
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  • 2
    Digitale Medien
    Digitale Medien
    A prospective evaluation of sensitivity and specificity of the ankle/brachial index in the follow-up of superficial femoral artery occlusions treated by angioplasty (1994)
    Springer
    Journal of molecular medicine 72 (1994), S. 592-597 
    Details
    ISSN: 1432-1440
    Schlagwort(e): Peripheral arterial obstructive disease ; Angioplasty ; Ankle/brachial index ; Sensitivity ; Specificity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The aim of this study was to provide estimates of sensitivity and specificity of clinical history, pulses, and ankle/brachial index (ABI) in the follow-up of atherosclerotic occlusions of the superficial femoral artery treated by peripheral transluminal angioplasty (PTA). A total of 116 patients were followed prospectively for 1 year after angioplasty with follow-up visits immediately after angioplasty, and at 3, 6, and 12 months. All patients underwent digital subtraction angiography after 1 year or if they reported a deterioration of their symptoms. Reobstruction was defined as reocclusion or as restenosis exceeding 70%. Patency rates were calculated separately by clinical and ankle/ brachial criteria; sensitivity and specificity were derived using angiography as standard. The presence or absence of pulses distal to the treated vessel segment had a sensitivity of 78% and a specificity of 66% for a reocclusion or significant restenosis; subjective complaints evaluated by history had a sensitivity of 83% and a specificity of 51%. The sensitivity of the ABI was 72% and 66%, with a specificity of 82% and 100% for cutoff values of 0.10 and 0.15, respectively. One year after PTA the angiographic patency rate was 39 % ± 5 %; the patency rate based on ABI criteria 34% ± 5%. A deterioration in the ABI by 0.15 indicated with reasonable certainty a reocclusion or significant restenosis whereas the sensitivity of the ABI was poor in detecting significant restenosis after PTA of occlusions of the superficial femoral artery. When only clinical criteria were used, the true patency rate was significantly overestimated as more than half of all reobstructions remained asymptomatic.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00227451
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  • 3
    Digitale Medien
    Digitale Medien
    Effects of adenosine on electrical activity of isolated guinea pig hearts (1993)
    Springer
    Basic research in cardiology 88 (1993), S. 23-32 
    Details
    ISSN: 1435-1803
    Schlagwort(e): Adenosine ; refractoriness ; cardiac conduction ; AV-node ; isolated heart preparation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Negative chronotropic and dromotropic effects of adenosine seem to be responsible for its antiarrhythmic action on supraventricular tachyarrhythmias. To further characterize the effects of adenosine on supraventricular arrhythmias heart rate, conduction, refractoriness, the time to steady-state of AV-nodal conduction slowing and of sinus rate reduction were evaluated. Changes of heart rate, conduction intervals and effective refractory periods were determined by the use of a high-resolution ECG recording technique in isolated guinea pig hearts perfused by the method of Langendorff. Adenosine in concentrations of 3 and 10 μM reduced sinus rate and prolonged AV-nodal conduction significantly, while intraventricular and His bundle conduction were not altered. The maximal effect of adenosine on the sinus node and AV nodal conduction occurred after 636±109 and 111±35 (mean±SE) beats, respectively. During programmed stimulation at a cycle length of 250 ms, adenosine reduced atrial ERP in a dose-dependent manner. At cycle lengths of 170 and 200 ms, adenosine increased the atrial ERP at 3 μM, and then progressively shortened the ERP at higher doses. At all adenosine concentrations used, the usual rate-dependent adaption in ERP was suppressed. These observations explain the efficacy of adenosine against supraventricular tachyarrhythmias where the AV-node forms a part of a reentrant circuit. Adenosine shortened the atrial ERP, but at high pacing rates also led to a relative prolongation of the atrial ERP as the rate-dependent adaption was suppressed. These opposite effects of adenosine may explain earlier contradictory findings of its action on atrial arrhythmias.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00788527
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