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Walter J Koch

Publications and source records attributed to Walter J Koch.

At least 19 recordsLinked to original sources
PubMed2007

Beta blocker specificity: a building block toward personalized medicine.

Drugs known as beta blockers, which antagonize the beta-adrenergic receptor (beta-AR), are an important component of the treatment regimen for chronic heart failure (HF). However, a significant body of evidence indicates that genetic heterogeneity at the level of the beta(1)-AR may be a factor in explaining the variable responses of HF patients to beta blockade. In this issue of the JCI, Rochais et al. describe how a single amino acid change in beta(1)-AR alters its structural conformation and improves its functional response to carvedilol, a beta blocker currently used in the treatment of HF (see the related article beginning on page 229). This may explain why some HF patients have better responses not only to carvedilol but to certain other beta blockers as well. The data greatly enhance our mechanistic understanding of myocardial adrenergic signaling and support the development of "tailored" or "personalized" medicine, in which specific therapies could be prescribed based on a patient's genotype.

Adrenergic beta-Antagonists↗
PubMed2006

Regulated overexpression of the A1-adenosine receptor in mice results in adverse but reversible changes in cardiac morphology and function.

BACKGROUND: Both the A1- and A3-adenosine receptors (ARs) have been implicated in mediating the cardioprotective effects of adenosine. Paradoxically, overexpression of both A1-AR and A3-AR is associated with changes in the cardiac phenotype. To evaluate the temporal relationship between AR signaling and cardiac remodeling, we studied the effects of controlled overexpression of the A1-AR using a cardiac-specific and tetracycline-transactivating factor-regulated promoter. METHODS AND RESULTS: Constitutive A1-AR overexpression caused the development of cardiac dilatation and death within 6 to 12 weeks. These mice developed diminished ventricular function and decreased heart rate. In contrast, when A1-AR expression was delayed until 3 weeks of age, mice remained phenotypically normal at 6 weeks, and >90% of the mice survived at 30 weeks. However, late induction of A1-AR still caused mild cardiomyopathy at older ages (20 weeks) and accelerated cardiac hypertrophy and the development of dilatation after pressure overload. These changes were accompanied by gene expression changes associated with cardiomyopathy and fibrosis and by decreased Akt phosphorylation. Discontinuation of A1-AR induction mitigated cardiac dysfunction and significantly improved survival rate. CONCLUSIONS: These data suggest that robust constitutive myocardial A1-AR overexpression induces a dilated cardiomyopathy, whereas delaying A1-AR expression until adulthood ameliorated but did not eliminate the development of cardiac pathology. Thus, the inducible A1-AR transgenic mouse model provides novel insights into the role of adenosine signaling in heart failure and illustrates the potentially deleterious consequences of selective versus nonselective activation of adenosine-signaling pathways in the heart.

Animals↗
PubMed2006

Cardiac-specific ablation of G-protein receptor kinase 2 redefines its roles in heart development and beta-adrenergic signaling.

G-protein receptor kinase 2 (GRK2) is 1 of 7 mammalian GRKs that phosphorylate ligand-bound 7-transmembrane receptors, causing receptor uncoupling from G proteins and potentially activating non-G-protein signaling pathways. GRK2 is unique among members of the GRK family in that its genetic ablation causes embryonic lethality. Cardiac abnormalities in GRK2 null embryos implicated GRK2 in cardiac development but prevented studies of the knockout phenotype in adult hearts. Here, we created GRK2-loxP-targeted mice and used Cre recombination to generate germline and cardiac-specific GRK2 knockouts. GRK2 deletion in the preimplantation embryo with EIIa-Cre (germline null) resulted in developmental retardation and embryonic lethality between embryonic day 10.5 (E10.5) and E11.5. At E9.5, cardiac myocyte specification and cardiac looping were normal, but ventricular development was delayed. Cardiomyocyte-specific ablation of GRK2 in the embryo with Nkx2.5-driven Cre (cardiac-specific GRK2 knockout) produced viable mice with normal heart structure, function, and cardiac gene expression. Cardiac-specific GRK2 knockout mice exhibited enhanced inotropic sensitivity to the beta-adrenergic receptor agonist isoproterenol, with impairment of normal inotropic and lusitropic tachyphylaxis, and exhibited accelerated development of catecholamine toxicity with chronic isoproterenol treatment. These findings show that cardiomyocyte autonomous GRK2 is not essential for myocardial development after cardiac specification, suggesting that embryonic developmental abnormalities may be attributable to extracardiac effects of GRK2 ablation. In the adult heart, cardiac GRK2 is a major factor regulating inotropic and lusitropic tachyphylaxis to beta-adrenergic agonist, which likely contributes to its protective effects in catecholamine cardiomyopathy.

Adrenergic beta-Agonists↗
PubMed2006

Cardiac S100A1 protein levels determine contractile performance and propensity toward heart failure after myocardial infarction.

BACKGROUND: Diminished cardiac S100A1 protein levels are characteristic of ischemic and dilated human cardiomyopathy. Because S100A1 has recently been identified as a Ca2+-dependent inotropic factor in the heart, this study sought to explore the pathophysiological relevance of S100A1 levels in development and progression of postischemic heart failure (HF). METHODS AND RESULTS: S100A1-transgenic (STG) and S100A1-knockout (SKO) mice were subjected to myocardial infarction (MI) by surgical left anterior descending coronary artery ligation, and survival, cardiac function, and remodeling were compared with nontransgenic littermate control (NLC) and wild-type (WT) animals up to 4 weeks. Although MI size was similar in all groups, infarcted S100A1-deficient hearts (SKO-MI) responded with acute contractile decompensation and accelerated transition to HF, rapid onset of cardiac remodeling with augmented apoptosis, and excessive mortality. NLC/WT-MI mice, displaying a progressive decrease in cardiac S100A1 expression, showed a later onset of cardiac remodeling and progression to HF. Infarcted S100A1-overexpressing hearts (STG-MI), however, showed preserved global contractile performance, abrogated apoptosis, and prevention from cardiac hypertrophy and HF with superior survival compared with NLC/WT-MI and SKO-MI. Both Gq-protein-dependent signaling and protein kinase C activation resulted in decreased cardiac S100A1 mRNA and protein levels, whereas Gs-protein-related signaling exerted opposite effects on cardiac S100A1 abundance. Mechanistically, sarcoplasmic reticulum Ca2+ cycling and beta-adrenergic signaling were severely impaired in SKO-MI myocardium but preserved in STG-MI. CONCLUSIONS: Our novel proof-of-concept study provides evidence that downregulation of S100A1 protein critically contributes to contractile dysfunction of the diseased heart, which is potentially responsible for driving the progressive downhill clinical course of patients with HF.

Animals↗
PubMed2006

S100A1 decreases calcium spark frequency and alters their spatial characteristics in permeabilized adult ventricular cardiomyocytes.

S100A1, a Ca2+-sensor protein of the EF-hand type, exerts positive inotropic effects in the heart via enhanced cardiac ryanodine receptor (RyR2) activity. Here we report that S100A1 protein (0.1microM) interacts with the RyR2 in resting permeabilized cardiomyocytes at free Ca2+-levels comparable to diastolic Ca2+-concentrations ( approximately 150nM). Alterations of RyR2 function due to S100A1 binding was assessed via analysis of Ca2+-spark characteristics. Ca2+-spark frequency, amplitude and duration were all reduced upon perfusion with 0.1microM S100A1 protein by 38%, 14% and 18%, respectively. Most likely, these effects were conveyed through the S100A1 C-terminus (S100A1-ct; amino acids 75-94) as the corresponding S100A1-ct peptide (0.1microM) inhibited S100A1 protein binding to the RyR2 and similarly attenuated frequency, amplitude and duration of Ca2+-sparks by 52%, 8% and 26%, respectively. Accordingly, the sarcoplasmic reticulum (SR) Ca2+-content was slightly increased but the stoichiometry of other accessory RyR2 modulators (sorcin/FKBP12.6) remained unaltered by S100A1. Hence, we propose S100A1 as a novel inhibitory modulator of RyR2 function at diastolic Ca2+-concentrations in rabbit ventricular cardiomyocytes.

Animals↗
PubMed2006

Pharmacological- and gene therapy-based inhibition of protein kinase Calpha/beta enhances cardiac contractility and attenuates heart failure.

BACKGROUND: The conventional protein kinase C (PKC) isoform alpha functions as a proximal regulator of Ca2+ handling in cardiac myocytes. Deletion of PKCalpha in the mouse results in augmented sarcoplasmic reticulum Ca2+ loading, enhanced Ca2+ transients, and augmented contractility, whereas overexpression of PKCalpha in the heart blunts contractility. Mechanistically, PKCalpha directly regulates Ca2+ handling by altering the phosphorylation status of inhibitor-1, which in turn suppresses protein phosphatase-1 activity, thus modulating phospholamban activity and secondarily, the sarcoplasmic reticulum Ca2+ ATPase. METHODS AND RESULTS: In the present study, we show that short-term inhibition of the conventional PKC isoforms with Ro-32-0432 or Ro-31-8220 significantly augmented cardiac contractility in vivo or in an isolated work-performing heart preparation in wild-type mice but not in PKCalpha-deficient mice. Ro-32-0432 also increased cardiac contractility in 2 different models of heart failure in vivo. Short-term or long-term treatment with Ro-31-8220 in a mouse model of heart failure due to deletion of the muscle lim protein gene significantly augmented cardiac contractility and restored pump function. Moreover, adenovirus-mediated gene therapy with a dominant-negative PKCalpha cDNA rescued heart failure in a rat model of postinfarction cardiomyopathy. PKCalpha was also determined to be the dominant conventional PKC isoform expressed in the adult human heart, providing potential relevance of these findings to human pathophysiology. CONCLUSIONS: Pharmacological inhibition of PKCalpha, or the conventional isoforms in general, may serve as a novel therapeutic strategy for enhancing cardiac contractility in certain stages of heart failure.

Animals↗
PubMed2006

Alpha2-adrenergic receptor subtype-specific activation of NF-kappaB in PC12 cells.

In the present study we sought to investigate the signal transduction mechanisms that underlie the alpha2-adrenergic receptor (AR)-induced, subtype-specific neuronal differentiation of PC12 cells. Alpha2-ARs induced NF-kappaB transcriptional activity and p21(waf-1) gene transcription in the same subtype-specific manner (alpha2A<alpha2B<alpha2C) as the neuronal differentiation induced by these receptors. Following pretreatment with the MEK1 inhibitor PD98059, the NF-kappaB response to epinephrine becomes uniform with loss of subtype specificity. In contrast, there is complete abolishment of epinephrine-induced transcription by NF-kappaB after pretreatment with the PI3-K inhibitor LY294002. These data imply that induction of transcription by NF-kappaB is PI-3K-dependent; however, the subtype-specific induction of transcription by NF-kappaB is ERK1/2-dependent. Taken together, these results suggest that the three alpha2-adrenoceptors promote an interaction between PI-3K and ERK1/2 in a subtype-specific way, leading to subtype-specific induction of transcription by NF-kappaB and p21(waf-1) gene transcription, which might underlie the subtype-specific differentiation of PC12 cells induced by these receptors.

Animals↗
PubMed2006

Chronic beta-adrenergic receptor stimulation induces cardiac apoptosis and aggravates myocardial ischemia/reperfusion injury by provoking inducible nitric-oxide synthase-mediated nitrative stress.

The present study provides evidence that inducible nitric-oxide synthase (iNOS)-mediated nitrative stress plays a pivotal role in chronic beta-adrenergic receptor (AR) stimulation-induced cardiac damage. In mice, 14 days of isoproterenol (ISO) stimulation via an osmotic minipump induced an up-regulation of iNOS as evidenced by increases in mRNA, protein expression, and immunochemical staining of myocardial iNOS. Serum level of C-reactive protein, an inflammatory mediator, was also markedly increased. Under chronic ISO stimulation, the up-regulated iNOS produced a significantly increased amount of nitric oxide (NO) and its byproduct, peroxynitrite, in the circulation and heart and subsequently resulted in an accelerated myocardial apoptosis. Forty-minute myocardial ischemia (MI) and 24-h reperfusion (R) further increased NO production and peroxynitrite formation and resulted in an enlarged infarct size in mice receiving chronic ISO stimulation. However, the treatment with a selective iNOS inhibitor [N-(3-(aminomethyl) benzyl)acetamidine] (1400W) or the use of a genetic modified animal (iNOS-knockout mice) markedly reduced iNOS-mediated production of NO and formation of peroxynitrite and consequently significantly decreased myocardial apoptosis and infarct size, showing a crucial link between iNOS-mediated nitrative stress and myocardial injury. In conclusion, chronic beta-AR stimulation up-regulates iNOS expression and increases NO production in the heart, which subsequently markedly enhances formation of reactive nitrogen species/peroxynitrite in the heart, thereby eliciting myocardial apoptosis and potentiating MI/R injury.

Adrenergic beta-Agonists↗
PubMed2006

Lymphocyte levels of GRK2 (betaARK1) mirror changes in the LVAD-supported failing human heart: lower GRK2 associated with improved beta-adrenergic signaling after mechanical unloading.

BACKGROUND: In human heart failure, increased expression of G protein-coupled receptor kinases (GRKs) causes the loss of beta-adrenergic receptor (betaAR) signaling and function. Mechanical unloading with a left ventricular assist device (LVAD) promotes reverse remodeling, which includes restoration of betaAR responsiveness. We tested the hypothesis that LVAD support of the failing human heart alters the expression and activity of GRKs and we sought to determine whether changes in myocardial GRKs could be tracked in lymphocytes. METHODS AND RESULTS: Paired samples of human LV tissue (n = 12) and blood were obtained at the time of LVAD implantation (heart failure) and subsequent cardiac transplantation (LVAD). betaAR signaling was quantified by receptor density and adenylyl cyclase activity. Immunoblotting and real-time reverse transcription polymerase chain reaction were used to measure GRK2 and GRK5 protein and mRNA levels. Rhodopsin phosphorylation was used to assess total GRK activity. Consistent with reverse remodeling, betaAR density and signaling were restored to nonfailing levels after LVAD support. GRK2 protein levels were significantly reduced 55% after LVAD support and GRK2 mRNA was similarly reduced. In contrast, GRK5 protein and mRNA levels were unchanged. Total myocardial GRK activity was reduced similar to the drop in GRK2 expression. In lymphocytes, GRK2 protein levels were decreased after LVAD support and there was a significant positive correlation between myocardial and lymphocyte GRK2 levels in both heart failure and LVAD samples. CONCLUSION: The changes in myocardial GRK2 expression and activity that are mirrored in lymphocytes provide a possible mechanism for the restoration of betaAR signaling and reverse remodeling after mechanical unloading in the failing heart. Moreover, lymphocytes may provide a surrogate marker of myocardial GRK2 in these patients.

Adult↗
PubMed2005

Ischemic neoangiogenesis enhanced by beta2-adrenergic receptor overexpression: a novel role for the endothelial adrenergic system.

Beta2-adrenergic receptors (beta2ARs) are widely expressed, although their physiological relevance in many tissues is not yet fully understood. In vascular endothelial cells, they regulate NO release and vessel tone. Here we provide novel evidence that beta2ARs can regulate neoangiogenesis in response to chronic ischemia. We used in vivo adenoviral-mediated gene transfer of the human beta2AR to the endothelium of the rat femoral artery and increased beta2AR signaling resulting in ameliorated angiographic blood flow and hindlimb perfusion after chronic ischemia. Histological analysis confirmed that beta2AR overexpression also produced benefits on capillary density. The same maneuver partially rescued impaired angiogenesis in spontaneously hypertensive rats (SHR), whereas gene delivery of the G-protein-coupling defective mutant Ile164 beta2AR failed to provide ameliorations. Stimulation of endogenous and overexpressed beta2AR on endothelial cells in vitro was found to regulate cell number by inducing proliferation and [3H]-thymidine incorporation through means of extracellular receptor-activated kinase and vascular endothelial growth factor. The beta2AR also has novel effects on endothelial cell number through stimulation of proapoptosis and antiapoptosis pathways involving p38 mitogen-activated protein kinase and PI3-kinase/Akt activation. Therefore, beta2ARs play a critical role in endothelial cell proliferation and function including revascularization, suggesting a novel and physiologically relevant role in neoangiogenesis in response to ischemia.

Animals↗
PubMed2005

S100A1 gene therapy preserves in vivo cardiac function after myocardial infarction.

Myocardial infarction (MI) represents an enormous clinical challenge as loss of myocardium due to ischemic injury is associated with compromised left ventricular (LV) function often leading to acute cardiac decompensation or chronic heart failure. S100A1 was recently identified as a positive inotropic regulator of myocardial contractility in vitro and in vivo. Here, we explore the strategy of myocardial S100A1 gene therapy either at the time of, or 2 h after, MI to preserve global heart function. Rats underwent cryothermia-induced MI and in vivo intracoronary delivery of adenoviral transgenes (4 x 10(10) pfu). Animals received saline (MI), the S100A1 adenovirus (MI/AdS100A1), a control adenovirus (MI/AdGFP), or a sham operation. S100A1 gene delivery preserved global in vivo LV function 1 week after MI. Preservation of LV function was due mainly to S100A1-mediated gain of contractility of the remaining, viable myocardium since contractile parameters and Ca(2+) transients of isolated MI/AdS100A1 myocytes were significantly enhanced compared to myocytes isolated from both MI/AdGFP and sham groups. Moreover, S100A1 gene therapy preserved the cardiac beta-adrenergic inotropic reserve, which was associated with the attenuation of GRK2 up-regulation. Also, S100A1 overexpression reduced cardiac hypertrophy 1 week post-MI. Overall, our data indicate that S100A1 gene therapy provides a potential novel treatment strategy to maintain contractile performance of the post-MI heart.

Adenoviridae↗
PubMed2005

Elevated myocardial and lymphocyte GRK2 expression and activity in human heart failure.

AIMS: The G protein-coupled receptor kinase-2 (GRK2 or beta-ARK1) regulates beta-adrenergic receptors (beta-ARs) in the heart, and its cardiac expression is elevated in human heart failure (HF). We sought to determine whether myocardial levels and activity of GRK2 could be monitored using white blood cells, which have been used to study cardiac beta-ARs. Moreover, we were interested in determining whether GRK2 levels in myocardium and lymphocytes may be associated with beta-AR dysfunction and HF severity. METHODS AND RESULTS: In myocardial biopsies from explanted failing human hearts, GRK activity was inversely correlated with beta-AR-mediated cAMP production (R(2)=-0.215, P<0.05, n=24). Multiple regression analysis confirmed that GRK activity participates with beta-AR density to regulate catecholamine-sensitive cAMP responses. Importantly, there was a direct correlation between myocardial and lymphocytes GRK2 activity (R(2)=0.5686, P<0.05, n=10). Lymphocyte GRK activity was assessed in HF patients with various ejection fractions (EFs) (n=33), and kinase activity was significantly higher in patients with lower EFs and was higher with increasing NYHA class (P<0.001). CONCLUSION: Myocardial GRK2 expression and activity are mirrored by lymphocyte levels of this kinase, and its elevation in HF is associated with the loss of beta-AR responsiveness and appears to increase with disease severity. Therefore, lymphocytes may provide a surrogate for monitoring cardiac GRK2 in human HF.

Aged↗
PubMed2005

Improved myocardial beta-adrenergic responsiveness and signaling with exercise training in hypertension.

BACKGROUND: Cardiac responses to beta-adrenergic receptor stimulation are depressed with pressure overload-induced cardiac hypertrophy. We investigated whether exercise training could modify beta-adrenergic receptor responsiveness in a model of spontaneous hypertension by modifying the beta-adrenergic receptor desensitizing kinase GRK2 and the abundance and phosphorylation of some key Ca2+ cycling proteins. METHODS AND RESULTS: Female spontaneously hypertensive rats (SHR; age, 4 months) were placed into a treadmill running (SHR-TRD; 20 m/min, 1 h/d, 5 d/wk, 12 weeks) or sedentary group (SHR-SED). Age-matched Wistar Kyoto (WKY) rats were controls. Mean blood pressure was higher in SHR versus WKY (P<0.01) and unaltered with exercise. Left ventricular (LV) diastolic anterior and posterior wall thicknesses were greater in SHR than WKY (P<0.001) and augmented with training (P<0.01). Langendorff LV performance was examined during isoproterenol (ISO) infusions (1x10(-10) to 1x10(-7) mol/L) and pacing stress (8.5 Hz). The peak LV developed pressure/ISO dose response was shifted rightward 100-fold in SHR relative to WKY. The peak ISO LV developed pressure response was similar between WKY and SHR-SED and increased in SHR-TRD (P<0.05). SHR-TRD showed the greatest lusitropic response to ISO (P<0.05) and offset the pacing-induced increase in LV end-diastolic pressure and the time constant of isovolumic relaxation (tau) observed in WKY and SHR-SED. Improved cardiac responses to ISO in SHR-TRD were associated with normalized myocardial levels of GRK2 (P<0.05). SHR displayed increased L-type Ca2+ channel and sodium calcium exchanger abundance compared with WKY (P<0.001). Training increased ryanodine receptor phosphorylation and phospholamban phosphorylation at both the Ser16 and Thr17 residues (P<0.05). CONCLUSIONS: Exercise training in hypertension improves the inotropic and lusitropic responsiveness to beta-adrenergic receptor stimulation despite augmenting LV wall thickness. A lower GRK2 abundance and an increased phosphorylation of key Ca2+ cycling proteins may be responsible for the above putative effects.

Adrenergic beta-Agonists↗
PubMed2005

Level of beta-adrenergic receptor kinase 1 inhibition determines degree of cardiac dysfunction after chronic pressure overload-induced heart failure.

BACKGROUND: Heart failure is characterized by abnormalities in beta-adrenergic receptor (betaAR) signaling, including increased level of myocardial betaAR kinase 1 (betaARK1). Our previous studies have shown that inhibition of betaARK1 with the use of the Gbetagamma sequestering peptide of betaARK1 (betaARKct) can prevent cardiac dysfunction in models of heart failure. Because inhibition of betaARK activity is pivotal for amelioration of cardiac dysfunction, we investigated whether the level of betaARK1 inhibition correlates with the degree of heart failure. METHODS AND RESULTS: Transgenic (TG) mice with varying degrees of cardiac-specific expression of betaARKct peptide underwent transverse aortic constriction (TAC) for 12 weeks. Cardiac function was assessed by serial echocardiography in conscious mice, and the level of myocardial betaARKct protein was quantified at termination of the study. TG mice showed a positive linear relationship between the level of betaARKct protein expression and fractional shortening at 12 weeks after TAC. TG mice with low betaARKct expression developed severe heart failure, whereas mice with high betaARKct expression showed significantly less cardiac deterioration than wild-type (WT) mice. Importantly, mice with a high level of betaARKct expression had preserved isoproterenol-stimulated adenylyl cyclase activity and normal betaAR densities in the cardiac membranes. In contrast, mice with low expression of the transgene had marked abnormalities in betaAR function, similar to the WT mice. CONCLUSIONS: These data show that the level of betaARK1 inhibition determines the degree to which cardiac function can be preserved in response to pressure overload and has important therapeutic implications when betaARK1 inhibition is considered as a molecular target.

Adenylyl Cyclases↗
PubMed2005

Distinct subcellular location of the Ca2+-binding protein S100A1 differentially modulates Ca2+-cycling in ventricular rat cardiomyocytes.

Calcium is a key regulator of cardiac function and is modulated through the Ca2+-sensor protein S100A1. S100 proteins are considered to exert both intracellular and extracellular functions on their target cells. Here we report the impact of an increased intracellular S100A1 protein level on Ca2+-homeostasis in neonatal ventricular cardiomyocytes in vitro. Specifically, we compare the effects of exogenously added recombinant S100A1 to those resulting from the overexpression of a transduced S100A1 gene. Extracellularly added S100A1 enhanced the Ca2+-transient amplitude in neonatal ventricular cardiomyocytes (NVCMs) through a marked decrease in intracellular diastolic Ca2+-concentrations ([Ca2+]i). The decrease in [Ca2+]i was independent of sarcoplasmic reticulum Ca2+-ATPase (SERCA2a) activity and was probably the result of an increased sarcolemmal Ca2+-extrusion through the sodium-calcium exchanger (NCX). At the same time the Ca2+-content of the sarcoplasmic reticulum (SR) decreased. These effects were dependent on the uptake of extracellularly added S100A1 protein and its subsequent routing to the endosomal compartment. Phospholipase C and protein kinase C, which are tightly associated with this subcellular compartment, were found to be activated by endocytosed S100A1. By contrast, adenoviral-mediated intracellular S100A1 overexpression enhanced the Ca2+-transient amplitude in NVCMs mainly through an increase in systolic [Ca2+]i. The increased Ca2+-load in the SR was based on an enhanced SERCA2a activity while NCX function was unaltered. Overexpressed S100A1 colocalized with SERCA2a and other Ca2+-regulatory proteins at the SR, whereas recombinant S100A1 protein that had been endocytosed did not colocalize with SR proteins. This study provides the first evidence that intracellular S100A1, depending on its subcellular location, modulates cardiac Ca2+-turnover via different Ca2+-regulatory proteins.

Animals↗
PubMed2005

Catheter-mediated subselective intracoronary gene delivery to the rabbit heart: introduction of a novel method.

BACKGROUND: Recent studies suggest that gene therapy using replication-deficient adenoviruses will benefit treatment of cardiovascular diseases including heart failure. A persistent hurdle is the effective and reproducible delivery of a transgene to the myocardium with minimal iatrogenic morbidity. In this study, we sought to design a relatively non-invasive percutaneous gene delivery system that would maximize cardiac transgene expression and minimize mortality after intracoronary adenovirus injection. METHODS: Adult rabbits received a left circumflex coronary artery (LCx) infusion of 5x10(11) total viral particles of an adenovirus containing the marker transgene beta-galactosidase (Adeno-betaGal) via either a continuous infusion method utilizing an oxygenated, normothermic, physiologic pH Krebs solution driven by a Langendorff apparatus (n=12) or a timed bolus and set concentration at a constant infusion rate to the LCx (n=12). Six rabbits underwent global transgene delivery via an invasive method involving intraventricular delivery and aortic root cross-clamping. The efficacy of transgene expression via these three distinct delivery methods was determined in the left ventricle at 5 days by histological staining and colorimetric quantification assay. RESULTS: While the open-chest, aortic cross-clamping method provides the highest level of gene expression throughout the heart, the morbidity of this procedure is clinically prohibitive. Percutaneous LCx delivery of Adeno-betaGal using the Langendorff apparatus was associated with the lowest morbidity and mortality while still supporting significant myocardial gene expression. CONCLUSIONS: Percutaneous delivery of an adenovirus solution using a continuous infusion of oxygenated Krebs solution via a Langendorff apparatus appears to be a gene delivery modality offering the best compromise of gene expression and clinical utility to maximize any potential therapeutic outcome.

Adenoviridae↗