Skip Navigation

European Journal of Heart Failure 2000 2(1):23-31; doi:10.1016/S1388-9842(99)00072-0
This Article
Right arrow Abstract Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (12)
Right arrowRequest Permissions
Right arrow Disclaimer
Google Scholar
Right arrow Articles by Ungerer, M.
Right arrow Articles by Schwaiger, M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ungerer, M.
Right arrow Articles by Schwaiger, M.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© 2000 European Society of Cardiology

Regional pre- and postsynaptic sympathetic system in the failing human heart — regulation of βARK-1

Martin Ungerera,*, Hans-Jörg Weiga, Susanne Küberta, Matthias Overbeckb, Frank Bengelc, Albert Schömiga and Markus Schwaigerc

a Medizinische Klinik der Technischen Universität München, Klinikum rechts der Isar Ismaningerstr. 22, 81675 Munich, Germany
b Herzchirurgie, Deutsches Herzzentrum, Technische Universität München Munich, Germany
c Nuklearmedizinische Klinik, Technische Universität München Munich, Germany

* Corresponding author. Tel.: +49-89-4140-2947; fax: +49-89-4140-4901.E-mail address: ungerer{at}med1.med.tu-muenchen.de


   Abstract
Top
 Abstract
1. Introduction
 2. Materials and methods
 3. Results
 4. Discussion
 References
 
Objectives: Regional presynaptic sympathetic innervation varies considerably in the cardiomyopathic human heart, as shown in previous studies in vivo and in vitro. The goal of the present study was to correlate markers of presynaptic sympathetic innervation with local measurement of the postsynaptic β-adrenergic system in failing human hearts.

Methods and results: In nine left ventricular regions of hearts explanted from patients suffering from dilated cardiomyopathy, we measured the density of uptake1 carriers ([3H]mazindol binding) as a marker of presynaptic function as well as β-receptor density ([3H]CGP 12177 binding) and βARK-1 levels as the pivotal compounds of postsynaptic adrenergic signal transduction. Additionally, a subgroup of the patients was examined in vivo by HED-PET prior to heart transplantation. The density of uptake1 was related to local hydroxyephedrine (HED) retention (as determined by pre-operative PET, r=0.65), whereas it was inversely correlated to regional βARK-1 levels (r=–0.61, P=0.04). In contrast, β-adrenergic receptor density was not significantly correlated either to uptake1 density or to local HED retention (r=0.15 and r=0.21).

Conclusions: Regional βARK-1 levels rather than β-adrenergic receptor density were correlated with presynaptic alterations in cardiomyopathic human left ventricles. It can be assumed that in the cardiomyopathic human heart, regional β-adrenergic desensitization might be determined by differences in local βARK levels rather than by changes in β-receptor density.

Key Words: Heart failure • β-Receptors • β-Adrenergic receptor kinase-1

Received April 19, 1999; Revised November 1, 1999; Accepted December 1, 1999


   1. Introduction
Top
 Abstract
 1. Introduction
2. Materials and methods
 3. Results
 4. Discussion
 References
 
Heart failure is characterized by a markedly increased local cardiac sympathoadrenergic drive [1]. In previous studies [2,3], we have determined local alterations of the presynaptic sympathetic system in vivo and in vitro in the hearts of patients with dilated cardiomyopathy. Most of these patients displayed a strikingly common feature of decreased cardiac uptake1 activity and density in the infero-apical and apical myocardium, corresponding to the extent of regional tissue norepinephrine depletion. This finding suggests marked local differences in sympathoadrenergic drive in the failing heart and corresponding local variations of synaptic norepinephrine release in vivo. In contrast, normal volunteers show markedly less heterogeneity of cardiac presynaptic uptake than patients with heart failure [3].

In the present study, we investigated regional left ventricular differences in the components of the postsynaptic β-adrenergic system, since these proteins have been described to be regulated by agonist concentration in various biological systems. The activity of the β-adrenergic pathway is mostly determined by the density of β-receptors and by the activity of β-adrenergic receptor kinase-1 (βARK-1), an enzyme that phosphorylates and thereby inactivates agonist-occupied receptors. Increased receptor agonist levels have been shown to down-regulate β-receptor density in several models [4]. On the other hand, myocardial βARK-1 levels were increased after chronic exposure to β-agonists and decreased after administration of β-antagonists in a dose-dependent manner [5,19].

A down-regulation of cardiac β-adrenergic receptor density and function has been documented in heart failure both in humans and animals [6–8]. Additionally, increases in βARK activity and density have been described in various models of heart failure [8–11]. Both alterations probably contribute to the marked loss of responsiveness to β-adrenergic stimulation which is observed in the failing heart [3–5]. Also during cardiac ischemia, a fast activation and translocation of βARK-1 probably accounts for the rapid uncoupling and blunting of β-adrenergic signal transduction within minutes [25].

Several studies have shown that the regulation of cardiac βARK levels has strong effects on cardiac contractility. Transgenic mice which over-expressed βARK-1 in their hearts showed dampened contractility, whereas another line of transgenic mice which expressed a βARK inhibitor peptide displayed increased cardiac contractility when compared to wild-type littermates [11]. In genetically altered mice with heterozygous knock-out of βARK-1 [βARK-1 (–/+) mice], myocardial contractility was inversely related to cardiac βARK expression and activity [12].

Therefore, we set out to investigate the regional regulation of βARK-1 expression in comparison to local β-adrenergic receptor density in the failing human heart. Patients with heart failure due to dilated cardiomyopathy were investigated by hydroxyephedrine (HED)-PET to assess the functional activity of uptake1 in vivo. The regional density and affinity of uptake1 carrier proteins were measured by radioligand binding in explanted human hearts at the time of transplantation. Simultaneously, the local density and the affinity of β-adrenergic receptors were quantified by radioligand binding, and βARK-1 levels were determined by Western blotting.


   2. Materials and methods
Top
 Abstract
 1. Introduction
 2. Materials and methods
3. Results
 4. Discussion
 References
 
2.1. Patients and study protocol
The study was performed with nine patients suffering from heart failure (NYHA IV) due to dilated cardiomyopathy who were on the waiting list for heart transplantation (Table 1). All patients suffered from non-ischemic dilated cardiomyopathy. The research protocol was approved by the institutional ethical committee. The investigation conformed with the principles outlined in the Declaration of Helsinki. Each subject gave written informed consent prior to entering the study. Medical therapy consisted of diuretics and enalapril in all cases. None of the patients received β-blockers or β-agonists.


View this table:
[in this window]
[in a new window]

  		Table 1 Clinical data from preoperative cardiac catheterization of the patients with dilated cardiomyopathy included into the studya

 
2.2. Positron emission tomography
A subgroup of four patients was investigated by HED-PET prior to heart transplantation. All PET studies were performed on a Siemens/CTI 951 15-slice whole body tomograph. A detailed description of the synthesis of [11C]hydroxyephedrine (HED) and the course of investigation has been outlined in a previous study [2].

2.3. Human tissue
Tissue samples from the hearts of all nine patients included were taken after explantation. The mean time interval between PET study and transplantation was 3 months. All patients gave written informed consent prior to operation. Cardiac surgery was performed on cardiopulmonary bypass. The whole explanted heart was then placed on ice immediately after removal from the body, allowing a standardized identification of apical and basal areas, and of anterior, inferior, septal and lateral walls. Equal amounts of tissue were cut from the central portion of each anatomically defined segment of the left ventricular wall. After excision, the tissue was cut into small pieces and frozen in liquid nitrogen within 15 min from explantation and stored at –80°C.

2.4. Preparation of cardiac membranes
For preparation of membranes, tissues from each of the nine different regions were cut to pieces with a scalpel, resuspended in ice-cold lysis buffer [5 mmol/l Tris–HCl (pH 7.4), 2 mmol/l EDTA] and homogenized for 30 s in an ultraturrax tissue mincer. The homogenate was centrifuged at 1000xg for 15 min to remove cell debris and nuclei, and the supernatant was centrifuged twice at 100 000xg for 30 min. The resulting membrane pellet was resuspended in a buffer containing 50 mmol/l Tris–HCl (pH 7.5), 100 mmol/l NaCl and 5 mmol/l KCl, and used for radioligand binding. Protein concentration was determined according to Bradford [18].

2.5. Radioligand binding for uptake1
Incubation of membranes with [3H]mazindol (NEN-DuPont) in concentrations ranging from 0.5 to 30 nmol/l was carried out in 50 mmol/l Tris–HCl (pH 7.5), 100 mmol/l NaCl, and 5 mmol/l KCl, with or without 10 µmol/l desipramine to define non-specific binding, for 20 min at 22°C in a volume of 200 µl. On average, 207 µg protein per tube were used. All conditions were chosen as described before [2]. The binding was fully saturable and showed a linear dependence on the amount of membrane protein used. Specific binding depended on the presence of sodium ions and was not detectable in the absence of sodium. Optimum binding was achieved at a concentration of 100 mmol/l NaCl.

2.6. Radioligand binding for β-receptors
The binding assay for β-adrenergic receptors was carried out similarly. The radioligand [3H]CGP 12177 was used in concentrations ranging from 0.05 to 5 nmol/l, and incubation lasted for 60 min. Propranolol (3 µmol/l) was used as an antagonist to determine non-specific binding. In contrast to uptake1 binding, the incubation buffer did not contain NaCl or KCl.

2.7. Termination of the binding assay
The reaction was terminated by filtration through GF/B filters and washing with ice-cold incubation buffer. Filter radioactivity was determined by liquid scintillation counting. Uptake1-carrier or β-receptor density and affinity were determined from Scatchard plots of the counting data. The binding of [3H]mazindol and of [3H]CGP 12177 to membrane preparations from human ventricular were both characterized by low non-specific binding [2].

2.8. βARK-1 levels
Membrane extracts for Western blotting were prepared simultaneously. Samples containing 100 µg of protein were suspended in Laemmli buffer by gentle shaking for 15 min and electrophoresed on 12%-SDS polyacrylamide gels. The proteins were then blotted onto Amersham Hybond C membranes. Efficiency of transfer was verified by Ponceau red staining of the blots. The blots were blocked by adding 3% non-fat dry milk and 1% ovalbumin in PBS. βARK-1 was detected by probing with the antibody GRK-2 purchased from Santa Cruz Biosystems using chemoluminescent substrate (ECL, Amersham) and Kodak XAR films. To control specificity, the GRK-2 peptide sold by Santa Cruz Biosystems was used. Due to the sequence specificity of the βARK-1 epitope used, this antibody does not cross-react with other GRK isoforms. Blots were analyzed densitometrically using NIH graphics software after digitalized scanning.

2.9. βARK activity
βARK activity was measured in cardiac membranes by testing their capacity to phosphorylate light-activated rhodopsin, as described before [25]. Rod outer segments were prepared from bovine retinae and treated with urea. Tissue samples of 100 mg were taken from the left ventricles of human hearts and placed in 1 ml lysis buffer [25 mmol/l Tris–HCl (pH 7.5), 5 mmol/l EDTA, 5 mmol/l EGTA, 20 mg/ml leupeptin, 20 mg/ml benzamidin, 40 mg/ml phenylmethyl sulfonylfluorid (PMSF)]. The tissue was sonicated and minced in an ultraturrax, then centrifuged at 50 000xg for 30 min. The pellet from this step was resuspended in lysis buffer containing 250 mmol/l NaCl, and again homogenized. This suspension was recentrifuged and purified.

NaCl was added to 50 mmol/l. The preparation was equilibrated with 0.5 ml of 50% DEAE-sephacel (pH 7.0) for 15 min on ice, to be subsequently filtered through a glass wool column. Protein concentration was determined according to Bradford. From each sample, 50 µg was incubated with 500 pmol rhodopsin, 10 mmol/l MgCl2 and 0.3 mmol/l {gamma}-[32P]ATP. The reaction was terminated by diluting with 250 µl ice-cold lysis buffer. All samples were then centrifuged at 11 000xg. Free radioactivity in the supernatant was discarded and the pellet was dissolved in 30 µl 2x Laemmli buffer, and electrophoresed. Rhodopsin bands were cut from the gel, placed in scintillation vials and counted in a β-counter.

2.10. Statistics
Data are expressed as mean values ±S.E.M. For correlation of different parameters, a linear regression between two parameters was calculated, including 95% confidence intervals. A P-value below 0.05 was regarded as significant.


   3. Results
Top
 Abstract
 1. Introduction
 2. Materials and methods
 3. Results
4. Discussion
 References
 
3.1. Uptake1-carrier density
[3H]mazindol radioligand binding to membranes prepared from the different left ventricular regions revealed a marked variation in the density of uptake1 in all nine patients, with lowest values in the apical, infero-apical and basal lateral left ventricular walls. Mean uptake1 densities ranged between 75 and 170 fmol uptake1 sites/mg protein. These results were in accordance with our previous study in a different patient cohort [2]. The affinity of uptake1 (determined as kd-value of [3H]mazindol) showed some, though markedly less, regional variation. kd-Values ranged between 3 nmol/l and 10 nmol/l.

3.2. HED-PET
In the left ventricles of those patients who could be investigated prior to heart transplantation (n=4), HED retention was markedly reduced in the lateral and inferior apical walls. In contrast, PET imaging of perfusion documented nearly normal perfusion of all areas. Again, these results were in accordance with two earlier studies in different study populations [2,3]. For instance, the average flow-corrected HED retention was significantly lower in apical areas (0.81±0.03) than in the basal septal wall (1.14±0.03, P<0.05). Fig. 1 shows the distribution of mean uptake1 densities (ordinate) and flow-corrected HED-PET values (abscissa) throughout the nine different left ventricular regions of the four patients investigated by both methods, demonstrating a close correlation between the two parameters.


Figure 1
View larger version (9K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 1 Correlation of the regional distribution of mean uptake1 densities±S.E.M. (Bmax, abscissa) and mean flow-corrected HED-PET values±standard errors (ordinate) throughout the nine different left ventricular areas of the four patients who could also be investigated by PET prior to transplantation. Uptake1 densities are given as fmol/mg protein, and flow-corrected HED retentions are shown as arbitrary units.

 
3.3. β-Adrenergic receptors
Also β-receptor density showed some regional variation, which was, however, clearly less pronounced than the local differences in uptake1. Fig. 2 demonstrates the regional distribution of mean regional β-receptor densities (ordinate) in comparison to the uptake1 densities of the same areas (abscissa) of all nine patients included into the study. The affinity of β-receptors, determined as the kd-value of [3H]CGP 12177, was fairly homogeneous, ranging from 0.2 to 0.8 nmol/l. The average correlation coefficient between β-receptor density and uptake1 density amounted to 0.15 (not significant, see Table 2).


Figure 2
View larger version (9K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 2 Correlation of the regional distribution of mean uptake1 densities±S.E.M. (Bmax, ordinate) and mean β-receptor densities±S.E.M. (Bmax, abscissa) throughout the nine different left ventricular regions of all nine patients. Uptake1 and β-receptor densities are given as fmol/mg protein.

 


View this table:
[in this window]
[in a new window]

  		Table 2 Mean correlation coefficients (r) with 95% confidence intervals and error probabilities (P) for the correlation of flow-corrected HED retention (HED-PET), uptake1 density (uptake1), β-receptor density (β-receptors) and βARK-1 levels in 81 left ventricular regions of nine patients with dilated cardiomyopathy

 
3.4. βARK-1 levels
Fig. 3 shows a typical Western blot of βARK-1 levels in the nine areas of Patient 4. The strong signal at the expected size of 80 kDa could be inhibited by the addition of the specific peptide GRK-2. The mean distribution of local βARK-1 levels in all nine patients and their correlation to the respective presynaptic uptake1 densities can be seen from the data presented in Fig. 4. It is evident that local βARK-1 levels were inversely correlated to the respective changes in uptake1 density (Fig. 4). This finding was obvious in all investigated patients.


Figure 3
View larger version (28K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 3 Western blot of cardiac membranes prepared from the nine different left ventricular regions of Patient 4. The blots were exposed to antibody GRK-2 directed against the C terminus of βARK-1.

 


Figure 4
View larger version (9K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 4 Correlation of the regional distribution of mean uptake1 densities±S.E.M. (Bmax, ordinate) and mean βARK-levels±S.E.M. (Bmax, abscissa) throughout the nine different left ventricular regions of all nine patients. Uptake1 densities are given as fmol/mg protein, βARK-1 levels are indicated as arbitrary units.

 
3.5. βARK activity
In order to control our measurement of βARK-1 expression by using a second, independent method, it would have been preferable to also determine βARK activity in all investigated myocardial areas. Unfortunately, however, we could not obtain sufficient tissue material from each region to study βARK-1 Western blotting signals, receptor binding and βARK activity simultaneously. We therefore generated a standard curve of the correlation between local βARK activity and local βARK-1 expression in several pieces of human myocardium (n=3 patients) which allowed both determinations due to a larger sample size. Fig. 5 shows the excellent correlation between the two parameters in this representative sample. Hence, it can be assumed that the detection of local βARK-1 protein level is sufficiently representative also of the relative βARK activity in the respective myocardial area.


Figure 5
View larger version (8K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 5 Standard curve of the local βARK-1 level (Western blotting, arbitrary units) and the corresponding βARK activity (measured as pmol phosphate/min/mg protein) in five different areas from different patients, of which the sample size allowed both determinations.

 
Finally, all parameters were compared with each other, and correlation coefficients were calculated. Mean correlation coefficients with 95% confidence intervals and P-values based upon the analysis of 81 different areas in nine patients are indicated in Table 2.


   4. Discussion
Top
 Abstract
 1. Introduction
 2. Materials and methods
 3. Results
 4. Discussion
References
 
The present study documents a marked regional variation of uptake1-carrier density and HED retention in the left ventricles of patients with dilated cardiomyopathy, with lowest values in infero-lateral and apical areas. β-Adrenergic receptor density, however, showed less regional variation and was not significantly related to alterations in presynaptic uptake1. In contrast, local βARK-1 levels were inversely related to presynaptic changes. Decreased local uptake1 densities and, hence, increased norepinephrine release, were significantly correlated to elevated regional βARK-1 levels.

The finding of a marked local regulation of the presynaptic adrenergic components corroborates the results of our earlier study in a different patient cohort [2], and a study on overall regulation of presynaptic carrier regulation [27]. Also in the present study, we detected clear regional differences in the presynaptic sympathoadrenergic system. However, the analysis of local changes in the postsynaptic sympathetic system revealed a differential regulation of the individual components: local β-adrenergic receptor density varied less and was not significantly linked to presynaptic changes whereas strong increases in βARK-1 levels in areas of low uptake1 indicated strict dependence of βARK-1 levels on sympathoadrenergic activation in human myocardium, and hence, on increased concentrations of receptor agonists. This regulation would be expected since it has been shown in animal models that the chronic administration of β-agonists increases, whereas chronic exposure to β-antagonists decreases βARK levels and activity [5,19]. At present, the mechanisms which trigger cardiac βARK-1 gene transcription have not been fully elucidated. The promotor region and the genomic sequence of βARK-1 have been published, and they do not seem to contain a typical cAMP response element [20].

Receptor regulation by desensitization or down-regulation plays a key role in determining the functional state of the receptor and cellular responsiveness. In the failing myocardium, numerous alterations of the β-adrenergic pathway occur including a down-regulation of β1-adrenergic receptors [6–8], uncoupling of the remaining β-receptors from adenylyl cyclase [7], and increased expression of βARK-1 [8,17], an enzyme that phosphorylates and uncouples agonist-stimulated β-adrenergic receptors.

We have documented that myocardial β-adrenergic receptor density is not significantly linked to the distribution of uptake1 and HED retention in the failing human heart. This observation implies that β-receptor density does not depend very strictly on the respective extent of sympathoadrenergic activation. Pooling of these data with the data from our previous study [2] enabled us to calculate correlations for 17 patients with 154 individual regions. Also in this meta-analysis, we did not detect any significant correlation between β-receptor and uptake1 densities. Therefore, a statistical problem of small sample size does not seem to explain the obvious absence of linkage between the two parameters. In contrast, regional βARK-1 levels appear to be much more clearly determined by local sympathetic drive in human myocardium.

As different theories on the molecular pathogenesis of heart failure have been developed in recent years, several approaches for a molecular intervention to enhance cardiac function have been tested. Components which directly stimulate the β-adrenergic signaling cascade have been over-expressed in the hearts of transgenic mice. These interventions, however, led to the development of phenotypes which were cardiomyopathic and showed dampened contractility, as for example the over-expression of β2-receptors [14] or over-expression of Gs{alpha} [21,22]. In contrast, the approach to ‘resensitize’ the β-adrenergic signaling pathway by inhibiting βARK-1 had quite opposite effects. This concept was tested by over-expressing the βARK inhibitor peptide, ‘βARKmini’, consisting of the carboxyl terminus of βARK-1 [11]. Transgenic mice which over-expressed βARKmini in their hearts showed increased cardiac contractility for their whole lives without any signs of myocardial damage [11]. Additionally, it was reported that βARK-mini-expressing mice are protected against the deterioration of left ventricular function after aortic banding, whereas their wild-type littermates developed severe heart failure under this condition [12]. Also in a transgenic mouse model of heart failure due to disruption of actin filaments [MLP(–/–) mice], leading to severe cardiac structural defects and cardiomyopathy, over-expression of βARKmini prevented the development of heart failure [13]. Additionally, somatic gene transfer of βARKmini to cardiomyocytes led to diminished desensitization of the β-adrenergic pathway [15,16] and corrected the β-adrenergic signaling defects of failing cardiomyocytes by resensitizing the β-adrenergic pathway [15].

Therefore, the regulation of βARK levels and activity might play an important role in the development of heart failure, and might also represent a target for therapeutic interventions. Several β-blockers have been shown to be very effective in the treatment of heart failure [23]. Interestingly, these compounds differ profoundly in their effect on myocardial β-receptor density [24]. Whereas metoprolol up-regulates the reduced β-receptor density of the failing human heart, carvedilol and other β-blockers down-regulate it even further, despite the common capacity of these agents to improve LV myocardial function upon longer therapy [24]. In contrast, all compounds equally decrease cardiac βARK activity [19,26]. It can therefore be hypothesized that the therapeutic effect of β-blockers, such as carvedilol, in treating patients with heart failure might be due to an inhibition of cardiac βARK activity rather than to an interaction with β-receptor density [19].

In summary, marked regional variations of both, density of uptake1 and of βARK-1 levels were observed in failing human hearts. These differences were comparable to those measured by HED-PET. In contrast, regional density of β-receptors did not show a similar correlation to the other parameters.


   Acknowledgements
 
The help of Kai Kronsbein, biotechnologist, and that of PET technicians and radiochemists P. Watzlowik and J. Nevere is gratefully appreciated. This work was supported by a grant of the Deutsche Forschungsgemeinschaft (Un 103/3-2).


   References
Top
 Abstract
 1. Introduction
 2. Materials and methods
 3. Results
 4. Discussion
 References
 

  1. Bristow M.R., Minobe W., Rasmussen R., et al. β-Adrenergic neuroeffector abnormalities in the failing human heart are produced by local rather than systemic alterations. J Clin Invest (1992) 89:803–815.[Web of Science][Medline]
  2. Ungerer M., Hartmann F., Karoglan M., et al. Regional in vivo and in vitro characterization of autonomic innervation in cardiomyopathic human heart. Circulation (1998) 97:174–180.[Abstract/Free Full Text]
  3. Hartmann F., Ziegler S., Nekolla S., et al. Regional patterns of myocardial sympathetic denervation in dilated cardiomyopathy. An analysis using 11C-hydroxyephedrine and positron emission tomography. Heart (1999) 81(3):262–270.[Abstract/Free Full Text]
  4. Hadcock J.R., Malbon C.C. Down-regulation of β-adrenergic receptors: agonist-induced reduction in receptor mRNA levels. Proc Natl Acad Sci USA (1988) 85:5021–5025.[Abstract/Free Full Text]
  5. Iaccarino G., Lefkowitz J.R., Koch W.R. Reciprocal regulation of myocardial βARK1 by β-adrenergic agonists and antagonists. Circulation (1997) 96(suppl_I):I495.
  6. Bristow M.R., Anderson F.L., Port D.P., et al. Differences in β-adrenergic neuroeffector mechanisms in ischemic versus idiopathic dilated cardiomyopathy. Circulation (1991) 84:1024–1039.[Abstract/Free Full Text]
  7. Böhm M., Gierschik P., Jakobs K.H., et al. Increase of Gi{alpha} in human hearts with dilated but not ischemic cardiomyopathy. Circulation (1990) 82:1249–1265.[Abstract/Free Full Text]
  8. Ungerer M., Böhm M., Elce J.S., Erdmann E., Lohse M.J. Altered expression of β-adrenergic receptor kinase (βARK) and β1-adrenergic receptors in the failing human heart. Circulation (1993) 78:454–463.
  9. Ping P., Anzai T., Goa M., Hammond K. Adenylyl cyclase and G protein receptor kinase expression during development of heart failure. Am J Physiol (1997) 273:H707–H717.[Web of Science][Medline]
  10. Choi D.J., Koch W.J., Hunter J.H., Rockman H.A. Mechanism of β-adrenergic receptor desensitization in cardiac hypertrophy is increased β-adrenergic receptor kinase. J Biol Chem (1997) 272:17223–17229.[Abstract/Free Full Text]
  11. Maurice J.P., Kypson A.P., Skaer C.A., Koch W.J. β-Adrenergic signaling characteristics in an infarct heart failure model. Circulation (1997) 96(suppl 1):293.[Web of Science]
  12. Koch W.J., Rockman H.A., Samama P., et al. Cardiac function in mice overexpressing the β-adrenergic receptor kinase or a βARK inhibitor. Science (1995) 268:1350–1353.[Abstract/Free Full Text]
  13. Rockman H.A., Choi D.J., Akhter S.A., et al. Control of myocardial contractile function by the level of β-adrenergic receptor kinase 1 in gene-targeted mice. J Biol Chem (1998) 273:18180–18184.[Abstract/Free Full Text]
  14. Rockman HA, Chien KR, Choi DJ et al. Expression of β-adrenergic receptor kinase 1 inhibitor prevents the development of myocardial failure in gene-targeted mice. Proc Acad Natl Sci USA 1998;7000–7005.
  15. Drazner M.H., Peppel K.C., Dyer S., Grant A.O., Koch W.J., Lefkowitz R.J. Potentiation of β-adrenergic signaling by adenoviral-mediated gene transfer in adult rabbit ventricular myocytes. J Clin Invest (1997) 2:288–296.
  16. Laugwitz KL, Kronsbein K, Schmitt M et al. Characterization and inhibition of β-adrenergic receptor kinase in intact myocytes. Cardiovasc Res 35:324–333.
  17. Ungerer M, Parutti G, Böhm M et al. Expression of β-arrestins and β-adrenergic receptor kinases in the failing human heart. Circ Res 74:206–213.
  18. Bradford MM. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein dye binding. Anal Biochem 72:248–254.
  19. Ping P., Gelzer-Bell R., Roth D.A., Kiel D., Insel P.A., Hammond H.K. Reduced β-adrenergic receptor activation decreases G-protein expression and β-adrenergic receptor kinase activity in porcine heart. J Clin Invest (1995) 95:1271–1280.[Web of Science][Medline]
  20. Penn B.B., Benovic J.L. Structure of the human gene encoding the human β-adrenergic receptor kinase. J Biol Chem (1994) 169:14924–14930.
  21. Iwase M., Bishop S.P., Uechi M., et al. Adverse effects of chronic endogenous sympathetic drive induced by cardiac Gs overexpression. Circ Res (1996) 78:517–524.[Abstract/Free Full Text]
  22. Iwase M., Uechi M., Vatner D.E., et al. Cardiomyopathy induced by cardiac Gs{alpha} overexpression. Am J Physiol Heart Circ (1997) 41:H585–589.
  23. Packer M., Bristow M.R., Cohn J., et al. The effect of carvedilol on morbidity and mortality in patients with chronic heart failure. New Engl J Med (1996) 334:1349–1355.[Abstract/Free Full Text]
  24. Gilbert E.M., Abraham W.T., Olsen S., et al. Comparative hemodynamic, left ventricular functional, and antiadrenergic effects of chronic treatment with metoprolol versus carvedilol in the failing heart. Circulation (1996) 94:2817–2835.[Abstract/Free Full Text]
  25. Ungerer M., Kessebohm K., Kronsbein K., Lohse M.J., Richardt G. Activation of β-adrenergic receptor kinase during myocardial ischemia. Circ Res (1996) 79:455–460.[Abstract/Free Full Text]
  26. Iaccarino G., Tomhave D., Lefkowitz R.J., Koch W.J. Reciprocal in vivo regulation of myocardial G protein-coupled receptor kinase expression by β-adrenergic receptor stimulation and blockade. Circulation (1998) 98(17):1783–1789.[Abstract/Free Full Text]
  27. Böhm M., LaRosee K., Schwinger R.H.G., Erdmann E. Evidence for reduction of norepinephrine uptake sites in the failing human heart. J Am Coll Cardiol (1995) 25:146–153.[Abstract]

Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 JNMHome page
C. Kusmic, S. Morbelli, C. Marini, M. Matteucci, C. Cappellini, E. Pomposelli, P. Marzullo, A. L'Abbate, and G. Sambuceti
Whole-Body Evaluation of MIBG Tissue Extraction in a Mouse Model of Long-Lasting Type II Diabetes and Its Relationship with Norepinephrine Transport Protein Concentration
J. Nucl. Med., October 1, 2008; 49(10): 1701 - 1706.
[Abstract] [Full Text] [PDF]

Home page
 J. Appl. Physiol.Home page
J. G. Burniston, L.-B. Tan, and D. F. Goldspink
{beta}2-Adrenergic receptor stimulation in vivo induces apoptosis in the rat heart and soleus muscle
J Appl Physiol, April 1, 2005; 98(4): 1379 - 1386.
[Abstract] [Full Text] [PDF]

Home page
 Cardiovasc ResHome page
H. Luss, M. Schafers, J. Neumann, D. Hammel, C. Vahlhaus, H. A Baba, F. Janssen, H. H Scheld, O. Schober, G. Breithardt, et al.
Biochemical mechanisms of hibernation and stunning in the human heart
Cardiovasc Res, December 1, 2002; 56(3): 411 - 421.
[Abstract] [Full Text] [PDF]

Home page
 Eur Heart JHome page
A. L'Abbate and G. Sambuceti
Studying the neuronal side of the synaptic cleft. A tool for investigating the paradox of sympathetic nervous system and heart failure in dilated cardiomyopathy
Eur. Heart J., September 1, 2001; 22(17): 1521 - 1522.
[PDF]

This Article
Right arrow Abstract Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (12)
Right arrowRequest Permissions
Right arrow Disclaimer
Google Scholar
Right arrow Articles by Ungerer, M.
Right arrow Articles by Schwaiger, M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ungerer, M.
Right arrow Articles by Schwaiger, M.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?