Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1420-908X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract On helically cut strips of the rabbit's mesenteric artery, a temperature decrease from 42°C to 25°C reduced the contractile responses to histamine. Metiamide shifted the dose-response curve of the histamine-induced contraction towards higher values at 25°C, but not at 42°C. Furthermore, on arterial strips contracted by phenylephrine histamine evoked a dose-dependent relaxation at 25°C whereas at 42°C only slight relaxing responses to histamine occurred. Metiamide was capable of preventing the relaxation induced by histamine in a competitive manner. At 25°C the relaxation as produced by histamine was accompanied by increases in cyclic AMP which occurred prior to the relaxing effects. Metiamide abolished the cyclic AMP increase in response to histamine. At 42°C histamine was unable to elevate the cyclic AMP content. Thus, it is concluded that a cyclic AMP-mediated relexation due to stimulation of H2-receptors counteracts the histamine-induced contraction and reduces the contractile responses to histamine at low temperatures. In addition, clear-cut evidence exists from the present study that also on artery smooth muscle the H2-receptor-mediated responses are closely associated to cyclic AMP.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1420-908X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract On guinea-pig heart we investigated whether cyclic AMP serves as a messenger for H1- and/or H2-mediated responses to histamine. (1) On papillary muscle histamine elicited positive inotropic responses which were antagonized by burimamide but not by promethazine. The stimulation of H2-receptors was not only associated with an increase in contractility but also with an increase in cAMP. As shown by the time course of effects for 10−5 M histamine, the maximal increase in cAMP preceded the maximum in contractility. The mechanical and biochemical responses to histamine were potentiated by the phosphodiesterase inhibitor papaverine, but antagonized by burimamide. (2) On the left guinea-pig atrium containing H1-receptors the inotropic response to histamine (10−5 M) was not accompanied by increases in cAMP at stimulation frequencies of 0.5 and 2 Hz, respectively. In addition, in the presence of papaverine (3×10−5 M) no change in the cyclic AMP level occurred after application of histamine. Papaverine by itself, however, concomitantly increased contractility and cyclic AMP at a stimulation frequency of 0.5 Hz. In contrast, at 2 Hz papaverine increased only cAMP leaving the contractility unchanged. At this frequency the well-known Ca2+-antagonistic effect comes into prominence, thus masking the positive inotropic effect atributable to the inhibition of the phosphodiesterase. (3) On the right guinea-pig atrium the mediation of the positive charonotropic response to histamine by H2-receptors which is partly involved in the inotropic effect via the frequency-force relationship does not lead to a concomitant increase in cAMP. Also, in the presence of papaverine, histamine had no influence on the cAMP. However, papaverine potentiated the cardioacceleration produced by histamine. Although it is very likely that the cAMP in the sinus node rises, we were not able to detect an increase in cAMP in the whole atrial tissue. From the present results the conclusion can be drawn that the mediation of the inotropic effect due to stimulation of H2-receptors by histamine is associated with an increase of cyclic AMP, whereas that of H1-receptors is not. The view that cAMP may be the second messenger in the chronotropic action of histamine needs further elucidation by experiments on sino-atrial cells.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1420-908X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract On guinea-pig ileum and rabbit mesenteric artery contracted by high potassium (100 mM) histamine produced relaxations which were inhibited by the H2-receptor antagonist metiamide. These results are thus indicative for the role of H2-receptors in mediating relaxation and for H1-receptors in mediating contraction on smooth muscle. Time course studies for the relaxing and cyclic AMP responses to histamine showed that the cyclic AMP increase preceded the H2-receptor mediated relaxation. The cyclic AMP increase in response to histamine was prevented by metiamide, but remained unaffected by mepyramine on both the guinea-pig ileum and the rabbit mesenteric artery. In addition, dose-response curves obtained on the mesenteric artery demonstrated that the H2-receptor mediated depressor responses coincided with cyclic AMP increases. Thus, these results gave clear-cut evidence that cyclic AMP is an intracellular metabolic event only implicit in the H2-receptor mediated relaxation, but not in the H1-receptor mediated contraction on smooth muscle preparations.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1420-908X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract On guinea-pig atria part of the inotropic response to histamine is attributable to a concomitant increase of the frequency [7]. Since the chronotropic effect of histamine is mediated by a stimulation of H2-receptors a direct interaction of histamine with H1-receptors mediating the inotropic response on heart may be overlooked. For this reason the ability of the H1-antagonist promethazine and the H2-antagonist burimamide to inhibit the positive chronotropic, inotropic and coronary vascular responses to histamine was determined in spontaneously beating and electrically driven perfused guinea-pig hearts. (1) Burimamide produced a competitive blockade of the positive chrono- and inotropic responses to histamine. (2) On the other hand, promethazine in concentrations that had no effect on cardiac function by itself, proved to be ineffective against the positive chrono- and inotropic responses produced by histamine on spontaneously beating and electrically driven heart preparations. (3) The predominant coronary vasodilation observed after infusion with histamine was competitively antagonized by promethazine and burimamide. This blockade was not attributable to an interaction with myocardial H2-receptors mediating increases in heart rate and contractility and was, therefore, direct in nature. (4) Based upon the present study and former investigations [7] the following distribution of different histamine receptors in the guinea-pig heart does exist: H1-receptors are present in the atrial muscle and the coronary vascular bed. H2-receptors are located in the sinus node, the ventricular myocardium and the coronary vessels.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1432-1440
    Keywords: Exercise induced asthma ; Allergic asthma ; Histamine ; Catecholamines ; Theophylline ; Plasma levels ; Anstrengungsasthma ; allergisch-bedingtes Asthma ; Histamin ; Katecholamine ; Theophyllin ; Plasmaspiegel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Um zu untersuchen, ob endogene Transmitter bei der Auslösung und Unterhaltung verschiedener Formen des Asthma bronchiale eine Rolle spielen, haben wir bei Kindern vor und nach einer Laufbelastung sowie vor und nach einer inhalativen Provokation mit wäßrigen Allergenextrakten das Serumhistamin, Serumnoradrenalin und den bronchialen Strömungswiderstand (Rt) bestimmt. Die Untersuchung zeigt, daß das Belastungsasthma mit einem starken Anstieg des Plasmanoradrenalins, nicht jedoch des Plasmahistamins einhergeht. Dieser Anstieg war wesentlich ausgeprägter als der bei einem asthmatischen Vergleichskollektiv ohne Anstrengungsasthma. Im Gegensatz dazu zeigten die Kinder, die nach einer Allergenprovokation einen Asthmaanfall entwickelten, einen signifikanten Histamin-, jedoch keinen Noradrenalinanstieg. Zwischen Histamin-Serumspiegel und Stärke der Bronchokonstriktion bestand eine gute Korrelation (r=0.98). Nach oraler Applikation übte Theophyllin einen Schutz sowohl gegenüber dem Anstrengungsasthma, als auch gegenüber dem allergisch bedingten Asthma aus. Da Theophyllin beim allergisch ausgelösten Asthma nicht nur zu einem Abfall von Rt führte, sondern auch den Histaminanstieg verminderte, kann vermutet werden, daß ein Teil der Wirkung dieser Substanz beim allergischen Asthma auf einer Hemmung der Histaminfreisetzung beruht. Die Noradrenalinfreisetzung beim Anstrengungsasthma beeinflußte es nicht. Für seine protektive Wirkung bei dieser Asthmaform müssen daher andere Wirkungsmechanismen angenommen werden. Ob diese ausschließlich auf einer Relaxation beruhen, muß ungeklärt bleiben. Als Schlußfolgerung dieser Untersuchung wird deutlich, daß das Anstrengungsasthma und das allergische Asthma 2 verschiedene Typen eines Syndroms sind. Arzneimittel, die gegenüber beiden Typen wirksam sind, können dies über verschiedene Wirkungsmechanismen tun.
    Notes: Summary To investigate whether endogenous transmitters play a role in different forms of bronchial asthma we determined histamine and noradrenaline plasma levels as well as airway resistance (Rt) before and after exercise and allergen challenge in children. The study demonstrates that in exercise induced asthma (EIA) broncho-constriction was paralleled by increases of noradrenaline, but not of histamine plasma levels. This increase of noradrenaline was much more pronounced than that observed in the asthmatic control group not suffering from EIA. In contrast to what has been observed in EIA, bronchoconstriction in response to allergen challenge was closely associated with increases of histamine, but not of noradrenaline plasma levels. Between histamine concentrations and severity of illness a good correlation was found (r=0.98). Tests carried out after oral administration of theophylline showed a protection against EIAand allergic induced asthma. Since theophylline in allergic asthma concomitantly reduced the increase in Rt and plasma histamine it is suggested that at least part of the beneficial effects of theophylline in allergic asthma may result from inhibition of histamine release. In those children suffering from EIA theophylline did not affect noradrenaline release. Thus, consideration must be given to effects of theophylline against EIA which are based on other mechanisms. Whether these effects are solely attributable to relaxation of bronchial smooth muscle or not remains to be clarified. In conclusion this study clearly has identified exercise and allergic induced asthma as different types of the syndrome that we call asthma. Drugs which prevent against both types may do this by different modes of action.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 60 (1982), S. 983-990 
    ISSN: 1432-1440
    Keywords: Histamine-receptors ; Antihistamines ; Pharmacology ; Clinical use ; Side-effects ; Histamin-Rezeptoren ; Antihistaminika ; Pharmakologie ; Klinische Anwendung ; Nebenwirkungen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die H1-Antihistaminika werden seit über 30 Jahren zur Behandlung allergischer Erkrankungen eingesetzt. Viele von ihnen sind bisher jedoch noch nicht systematisch untersucht worden. Antihistaminika üben gegenüber der Histaminwirkung an isolierten Organen einen dualistischen Effekt aus, der aus einer kompetitiven und einer nicht-kompetitiven Komponente besteht. Zur Auslösung des nicht-kompetitiven Antagonismus sind gewöhnlich wesentlich höhere Dosen erforderlich, für das Dimethinden unterscheiden sich jedoch die Dosen zur Auslösung des kompetitiven und des nicht-kompetitiven Antagonismus nur um etwa 1 log Einheit. Bei der Therapie mit Antihistaminika muß berücksichtigt werden, daß einige bei Langzeitanwendung ihre Wirksamkeit verlieren und daß die sedierenden Effekte oft zu einer wesentlichen Beeinträchtigung führen. Es erscheint daher sinnvoll, zur Individualisierung der Therapie gegebenenfalls das Präparat zu wechseln, bevor das endgültige Therapieschema erstellt wird. Unter diesen Voraussetzungen sind die Antihistaminika erfolgreich bei vielen allergischen Erkrankungen einzusetzen. Beim Asthma bronchiale sind die klassischen Substanzen jedoch unwirksam. Die Suche nach neuen Wirkstoffen hat insofern zum Erfolg geführt, als mit dem Ketotifen ein neues wirksames Antihistaminikum/Antiallergikum zur Behandlung des Asthma bronchiale zur Verfügung steht. Viele Präparate, die bei der Behandlung “grippaler Infekte”, bei Vomitus und Rhinitiden eingesetzt werden, enthalten zusätzlich zum Antihistaminikum andere Pharmaka, die teilweise die unerwünschten Nebenwirkungen reduzieren sollen. Die Nebenwirkungen einiger Antihistaminika haben jedoch das Wirkungsspektrum andererseits erweitert. Dies gilt insbesondere für die zentralnervösen Effekte. Zusammen mit der weiteren Aufklärung der Funktion von Histamin als zentralnervöser Überträgersubstanz wird man bestrebt sein, Antihistaminika zu synthetisieren, die selektiver die zentralen Wirkungen des Histamins zu blockieren vermögen.
    Notes: Summary H1-antihistamines have been used in treatment of allergic disorders for more than 30 years. However, many of them have been employed in a less than systematic fashion. Most of the antihistamines show an apparent dual mechanism of action on isolated organs, consisting of a competitive and a non-competitive component. To induce non-competitive antagonism, higher concentrations are usually required, but for dimethindene the dose ratios for competitive and non-competitive activities differed only by less than one log unit. For therapeutic guidelines it should be considered that some antihistamines loose their effectiveness under long-term treatment and that patients may complain about the sedative side-effects. Thus, for maximum benefit it sometimes appears necessary to change the preparation before a choice for the individual dose is finally made. Under this condition they will cause relief from many allergic symptoms. Nevertheless, the classical antihistamines are without effect in bronchial asthma. The search for new drugs has been successful in this direction, as it has shown the antihistaminic/antiallergic drug Ketotifen to be able to prevent and control bronchial asthma. Many commercial preparations used in the treatment of common cold, vomitus or rhinitis contain an additive in combination with the antihistamines. Some of the additives appear to be of some value since they are used to reduce the side-effects of antihistamines. Secondary pharmacological properties of the antihistamines however provide also additional uses. This holds especially for effects on the CNS. Together with the search for the role played by histamine in the central cell-to-cell communication, new drugs might be found which will inhibit more selectively the action of histamine in the CNS.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1432-1440
    Keywords: Childhood asthma ; House dust mite allergy ; Bronchial provocation test ; Allergen-induced histamine release ; Basophile granulocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary It was suggested that 28 asthmatic children be sensitized against the house dust mite according to a positive case history and/or a positive result of the prick test and the radio-allergosorbent test (RAST). When these children underwent a bronchial provocation test with house dust mite allergen, 19 responded with a bronchoconstriction whereas nine remained unaffected. With the positive results there occurred a good correspondence with case history, prick test, and RAST, the latter being most valid in predicting results of bronchial reagibility to the house dust mite. On the other hand, those children who underwent bronchial provocation due to positive results in at least one of the allergy tests, but who did not respond with bronchoconstriction, showed no correspondence with either history or skin testing and RAST. However, when isolated basophiles from both children's groups were challenged with different house dust mite concentrations, the histamine release not only showed a good correspondence with the positive results of the bronchial provocation test, but also a correct prediction of the negative results could be made. Thus, of all allergy tests, the histamine liberation test appears to be the most valid for predicting the bronchial reagibility of asthmatic children to the house dust mite; this perhaps will allow a reduction in the frequency of inhalation challenges in those asthmatic children who are supposed to have been sensitized against house dust mite.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 71 (1993), S. 208-213 
    ISSN: 1432-1440
    Keywords: Allergy ; Whooping cough ; Pertussis toxin ; IgE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To evaluate whether pertussis induces the development of allergy, a prospective study was performed in 25 children aged 0.8–12.2 years. The patients underwent allergy diagnostics during pertussis infection and at a follow-up visit 8–14 months later. Diagnostic criteria included the medical history of the patients and their families, a modified skin prick test, measurement of serum IgE and radio-allergosorbent test screening for specific sensitizations. At the time of pertussis, serum IgE concentration in the study group was 62+ 30 kU/ml. At the follow-up visit, there was a significant increase in serum IgE to 137 ± 51 kU/ml, which was also significantly higher than IgE in an age-matched control group. Children at a significantly higher risk for developing IgE increase or new allergic sensitizations were those with a family history of allergy or potentially allergic disease in their personal history. Our results indicate that pertussis may induce IgE production in affected children.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1432-1076
    Keywords: Bronchial asthama ; Adrenergic theory ; α- and β-adrenoceptors ; Blood cells ; Age-dependent maturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Among the possible mechanisms which may cause wheezing or asthmatic episodes a genetically determined β-adrenoceptor blockade and a hyperresponsiveness of α-andrenoceptors has been postulated. Evidence to support this hypothesis stems from an increased bronchial sensitivity to β-blockers, a reduced formation of cyclic AMP in response to β-adrenergic stimulation and enhanced α-adrenergic responses in asthmatic subjects. The recent development of techniques for measuring the specific, high-affinity binding of radiolabeled α-and β-adrenergic antagonists made it possible to study α- and β-adrenoceptors in vitro. Based upon the assumption that a change in the number and/or affinity of adrenergic receptors might be a general phenomenon, we have performed α- and β-receptor binding studies on lymphocytes and platelets from wheezing infants and asthmatic children as well as of infants, children, and adults not suffering from these diseases. Using 125[I]-cyanopindolol (ICYP) and 3[H]-yohimbine (HYOH) as highly specific ligands for α- and β-adrenoceptors, the following results were obtained: (1) Lymphocytes and platelets from control subjects and asthamatics bound similar amounts of ICYP and HYOH and thus showed no differences either in the number or the affinity of α- and β-adrenoceptors. Lymphocytes and platelets of wheezing and nonwheezing infants also bound the same amounts of the radioligands. (2) In asthmatic children receiving 4×2 puffs salbutamol β-adrenoceptor were down-regulated and this may mimic β-adrenoceptor blockade. (3) When subjects were divided into four categories according to age (0–5, 5–10, 10–20 years, adults) the number of β-adrenoceptor binding sites showed an age-dependent increase. The number and affinity of α-adreneceptor binding sites on platelets was neither influenced by age nor disease. It is concluded that the α- and β-adrenoceptors of wheezing infants and asthmatic children at least on blood cells are normal. However the β-adrenoceptors show an age-dependent maturation process, which may account for an unresponsiveness to β-adrenoceptor agonists in wheezing infants.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Springer
    European journal of pediatrics 148 (1989), S. 286-293 
    ISSN: 1432-1076
    Keywords: Lung ; Adrenoceptors ; Molecular mechanisms ; Classification ; Function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract α- and β-Adrenoceptors have each been divided into two subgroups (α1, α2, β1 and β2). The basic mechanisms underlying the adrenoceptor/effector coupling are complex and vary for the α-, but not for the β-subpopulations. Adrenoceptors of the bronchi and the lung show a special pattern of distribution and response, ensuring that the airway system works as a functionary unit. Dysfunctions of adrenoceptormediated effects have been suggested to contribute to some important paediatric disorders such as hyaline membrane syndrome, wet lung, bronchial asthma, cystic fibrosis, and pertussis. Drugs which act on the adrenergic system influence some of these disorders directly. Further studies applying modern techniques to receptor research are needed in order to clarify the basic mechanisms involved in receptor-mediated lung disorders and the activity of drugs in lung tissue.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...