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Neurohormonal activation in patients with acute myocardial infarction or chronic congestive heart failure. With special reference to treatment with angiotensin converting enzyme inhibitors

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Abstract

Neurohormonal activation may provide a pathophysiological link between acute myocardial infarction and chronic congestive heart failure, and modulation of neurohormonal activity may be an important therapeutic target in these conditions. Plasma neurohormones were studied in 55 patients with acute myocardial infarction. Angiotensin II, noradrenaline and ANP were elevated in the early phase but tended to normalize during the first week in patients without signs of heart failure. In patients with heart failure angiotensin II and noradrenaline remained elevated for 1 month and ANP for 4-6 months. During head-up tilt, angiotensin II and noradrenaline increased most in patients with heart failure. In patients with a first myocardial infarction there was a positive correlation between sustained neurohormonal activity and infarct size. Almost complete suppression of plasma ACE activity was achieved within 30 min in 48 patients treated with intravenous enalaprilat, initiated within 24 h from the onset of infarction. The drug was tolerated in dosages of 1.0-1.2 mg given over 1-2h. Patients with systolic blood pressure between 100 and 110 mmHg incurred a greater risk of hypotension than those with higher blood pressure at baseline. Tolerance was not worse among patients treated with intravenous diuretics, metoprolol or nitroglycerin. A total of 98 patients were randomized to treatment with enalapril or placebo, initiated within 24 h from onset of infarction and continued for 4-6 months. During treatment there were no significant differences in plasma levels of angiotensin II, aldosterone, ANP or catecholamines between groups. Echocardiographic recordings were performed in 28 patients. Among patients on placebo there was a positive correlation between plasma levels of noradrenaline at days 5-7 and the increase in left ventricular volumes during the study period, and an inverse correlation between plasma aldosterone at days 5-7 and the increase in left ventricular ejection fraction during the study. No such correlation was found among patients on enalapril. ANP levels at 1 month correlated inversely with the left ventricular ejection fraction at the same time. Plasma neurohormones were measured in 223 patients with mild or moderately severe chronic heart failure, randomized to treatment with ramipril or placebo for 3 months. There was wide variation in hormone levels. Noradrenaline and aldosterone correlated inversely with exercise duration at baseline. Noradrenaline correlated positively with the degree of symptoms. Aldosterone and ANP were reduced with ramipril compared with placebo. Noradrenaline was reduced among patients with baseline levels in the highest tertile. Plasma hormones were also measured at peak exercise in 54 patients. Hormonal levels at rest correlated strongly with those at peak exercise.(ABSTRACT TRUNCATED AT 400 WORDS)

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... It is important to note that GRK-2 participates not only in desensitization of β-AR, but also in desensitization of other GPCRs in the cell, such are the adrenergic and muscarinic receptor family [23]. Role of G protein related kinase in coronary artery disease – evidence from animal studies Neurohormonal activation occurs early in the progression to HF, as reflected by increased catecholamine levels and adrenergic drive immedi ately after myocardial infarction (MI) and before progression to end-stage HF [24] . Therefore, sympathetic nervous activity has been investigated as a possible early trigger for increasing GRK activity in the failing myocardium. ...
... Therefore, sympathetic nervous activity has been investigated as a possible early trigger for increasing GRK activity in the failing myocardium. Excessive catecholamine stimulation modulates β-AR signaling and damps sympathetic signaling [24]. This is considered to be an adaptive mechanism to sympathetic overstimulation . ...
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In coronary artery disease the G protein related kinases (GRKs) play a role in desensitization of β-adrenoreceptors (AR) after coronary occlusion. Targeted deletion and lowering of cardiac myocyte GRK-2 decreases the risk of post-ischemic heart failure (HF). Studies carried out in humans confirm the role of GRK-2 as a marker for the progression of HF after myocardial infarction (MI). The level of GRK-2 could be an indicator of β-AR blocker efficacy in patients with acute coronary syndrome. Elevated levels of GRK-2 are an early ubiquitous consequence of myocardial injury. In hypertension an increased level of GRK-2 was reported in both animal models and human studies. The role of GRKs in vagally mediated disorders such as vasovagal syncope and atrial fibrillation remains controversial. The role of GRKs in the pathogenesis of neurocardiological diseases provides an insight into the molecular pathogenesis process, opens potential therapeutic options and suggests new directins for scientific research.
... In humans, neurohormonal activation such as adrenergic overdrive has been observed in patients acutely after cardiac stress/injury including after a myocardial infarction (230). In addition, increased levels of GRK2 have also been reported in other human studies of disease states (reviewed in Refs. ...
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G protein-coupled receptors (GPCRs) are important regulators of various cellular functions via activation of intracellular signaling events. Active GPCR signaling is shut down by GPCR kinases (GRKs) and subsequent β-arrestin-mediated mechanisms including phosphorylation, internalization, and either receptor degradation or resensitization. The seven-member GRK family varies in their structural composition, cellular localization, function, and mechanism of action (see sect. II). Here, we focus our attention on GRKs in particular canonical and novel roles of the GRKs found in the cardiovascular system (see sects. III and IV). Paramount to overall cardiac function is GPCR-mediated signaling provided by the adrenergic system. Overstimulation of the adrenergic system has been highly implicated in various etiologies of cardiovascular disease including hypertension and heart failure. GRKs acting downstream of heightened adrenergic signaling appear to be key players in cardiac homeostasis and disease progression, and herein we review the current data on GRKs related to cardiac disease and discuss their potential in the development of novel therapeutic strategies in cardiac diseases including heart failure. Copyright © 2015 the American Physiological Society.
... A prominent hypothesis is that the underlying mechanism involves an increase in the activity of GRK2, which phosphorylates and desensitizes the βAR as well as other GPCRs (Rockman et al., 2002;Hata and Koch, 2003). During progression to heart failure, sustained elevation of catecholamine levels leads to prolonged stimulation of βAR resulting in chronic desensitization of the receptor by GRK2 (Sigurdsson, 1995;Rundqvist et al., 1997;Hata and Koch, 2003). Gβγ recruits GRK2 to the receptor (Pitcher et al., 1992). ...
... The most pronounced activation was observed in the group of patients with impaired systolic cardiac function at discharge. This observation is in accordance with studies describing that activation in this system is related to infarct size and to indices of ventricular function [18]. ...
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Es wurden die Plasmaspiegel der untersuchten Neurohormone wie auch die hämodynamischen Parameter Belastungstoleranz, Herzfrequenz, sowie systolischer und diastolischer Blutdruck bei Untersuchungsbeginn, sowie nach 4, 12 und 24 Wochen erfasst. Die Bestimmung der linksventrikulären Auswurffraktion erfolgte zu Studienbeginn sowie nach 12 und 24 Wochen, die des kardiothorakalen Quotienten zu Beginn und am Ende der Studie. Perindopril führte zu einem Anstieg des mittleren Renin-Plasmaspiegels, der zu allen Untersuchungszeitpunkten das Signifikanzniveau sowohl im Vergleich zum Untersuchungsbeginn als auch im Vergleich zur Placebogruppe erreichte. Der Plasmaspiegel von Aldosteron lag zu allen Untersuchungszeitpunkten in der Verumgruppe unterhalb des Ausgangsniveaus, ein signifikanter Unterschied im Vergleich mit dem Untersuchungsbeginn konnte jedoch nicht erreicht werden. Nur zum Zeitpunkt 12 Wochen bestand ein signifikanter Unterschied im Vergleich zur Placebogruppe. Diese Ergebnisse weisen auf eine langanhaltende Hemmung des Angiotensin-Converting-Enzyms während des gesamten Untersuchungsverlaufes durch Perindopril hin. Ob eine Dosiserhöhung zu einer stärkeren Suppression des Aldosteronspiegels führt, sollte durch weitere Untersuchungen geklärt werden. Perindopril führte zu keiner signifikanten Änderung des ANF-Plasmaspiegels während des gesamten Untersuchungsverlaufes. Der Plasmaspiegel von cGMP wurde durch Perindopril gesenkt, ein Signifikanzniveau konnte aber nur zum Zeitpunkt 4 Wochen im Vergleich zum Studienbeginn erreicht werden. Auch hier sollte geprüft werden, ob eine Dosiserhöhung von Perindopril zu einem stärkeren Einfluss auf diese Parameter führen kann. Überraschenderweise kam es in der Verumgruppe zu einem Anstieg des Plasmaspiegels von Endothelin-1, der das Signifikanzniveau zu den Zeitpunkten 12 und 24 Wochen im Vergleich zum Studienbeginn erreichte. Durch weitere Untersuchungen sollte geklärt werden, ob es sich hier um eine substanzspezifische Wirkung von Perindopril handelt. Eine Beeinflussung des Vasopressin-Plasmaspiegels durch Perindopril konnte nicht gezeigt werden. Eine signifikante lineare Korrelation innerhalb der neurohumoralen Parameter ergab sich nur für ANF und cGMP sowie in schwächerer Form für cGMP und Vasopressin. Zwischen hämodynamischen und neurohumoralen Messgrößen ergaben sich für ANF und cGMP signifikante positive lineare Korrelationen mit der linksventrikulären Auswurffraktion sowie negative Korrelationen mit dem kardiothorakalen Quotienten. Für Vasopressin konnte eine schwache positive lineare Korrelation mit dem diastolischen Blutdruck und der Herzfrequenz nachgewiesen werden. Auffallend war eine starke Streuung der Einzelwerte sämtlicher gemessener Plasmaspiegel. Die Ergebnisse zeigen, dass die Aktivierung der einzelnen neurohumoralen Systeme nicht parallel, sondern interindividuell verschieden und komplex verläuft. Nur für cGMP als second messenger konnte eine Koinzidenz mit ANF nachgewiesen werden. Ansonsten ist der Rückschluss von der Aktivierung eines neurohumoralen Systems auf ein anderes bei Patienten mit Herzinsuffizienz im Stadium NYHA II-III nicht möglich. Von den gemessenen neurohumoralen Parametern haben nur die Plasmaspiegel von ANF und vor allem cGMP eine verwertbare Aussagekraft als humorale Marker für die linksventrikuläre Funktion bei Patienten mit chronischer Herzinsuffizienz im Stadium NYHA II-III.
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The objective of this study was to determine whether the magnitude of adrenergic activation, as measured by plasma norepinephrine concentration (PNE) in the acute phase of myocardial infarction, may be useful as an independent predictor of long-term morbidity and mortality following acute myocardial infarction (AMI). Plasma norepinephrine was obtained within 3 days of admission to the cardiac intensive care unit in 146 randomly selected patients presenting with their first AMI. We analysed the relationship between the initial PNE and the clinical outcomes of death, reinfarction, and congestive heart failure during the subsequent 18 months. Patients with initial PNE over 565 pg/ml (n = 54) were found to have a significantly higher likelihood of cardiac death within the following 18 months (RR = 4.22; p = 0.04), as compared with patients with a lower PNE (n = 98). Even adjustment for variables significant on the univariate level, the difference in mortality remained significant (RR = 4.67; p = 0.03). No correlation was found between PNE and subsequent incidence of reinfarction and congestive heart failure in these patients (RR = 0.087; p = 0.80 and RR = 1.00; p = 0.09, respectively). Our observations support the hypothesis that PNE obtained early in the course of myocardial infarction can be a useful independent prognostic tool for post-AMI mortality.
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G proteins mediate the action of G protein coupled receptors (GPCRs), a major target of current pharmaceuticals and a major target of interest in future drug development. Most pharmaceutical interest has been in the development of selective GPCR agonists and antagonists that activate or inhibit specific GPCRs. Some recent thinking has focused on the idea that some pathologies are the result of the actions of an array of GPCRs suggesting that targeting single receptors may have limited efficacy. Thus, targeting pathways common to multiple GPCRs that control critical pathways involved in disease has potential therapeutic relevance. G protein betagamma subunits released from some GPCRs upon receptor activation regulate a variety of downstream pathways to control various aspects of mammalian physiology. There is evidence from cell- based and animal models that excess Gbetagamma signaling can be detrimental and blocking Gbetagamma signaling has salutary effects in a number of pathological models. Gbetagamma regulates downstream pathways through modulation of enzymes that produce cellular second messengers or through regulation of ion channels by direct protein-protein interactions. Thus, blocking Gbetagamma functions requires development of small molecule agents that disrupt Gbetagamma protein interactions with downstream partners. Here we discuss evidence that small molecule targeting Gbetagamma could be of therapeutic value. The concept of disruption of protein-protein interactions by targeting a "hot spot" on Gbetagamma is delineated and the biochemical and virtual screening strategies for identification of small molecules that selectively target Gbetagamma functions are outlined. Evaluation of the effectiveness of virtual screening indicates that computational screening enhanced identification of true Gbetagamma binding molecules. However, further refinement of the approach could significantly improve the yield of Gbetagamma binding molecules from this screen that could result in multiple candidate leads for future drug development.
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