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1.
Biomed Pharmacother ; 154: 113615, 2022 Oct.
Article in English | MEDLINE | ID: mdl-36057219

ABSTRACT

AIMS: Hospitalization for heart failure treatment (HHF) is an incisive event in the course of HF. Today, the large majority of HHF patients is ≥ 65 years and discharge HF drugs are most often not applied at dose levels acknowledged to provide prognostic benefit. This study therefore aims to investigate the treatment effect size of discharge HF drugs in old HHF patients. METHODS: Drugs are analyzed according to pharmacological class. Individual discharge HF drug dose is reported as percentage of guidelines-recommended target dose. Primary endpoint was 1-year all-cause mortality (ACM) after discharge; the secondary endpoint combined 1-year ACM and first cardiovascular hospitalization within 1 year after discharge. Comparison between 65-80 years and > 80 years old study participants tested the relative treatment effect size as a function of respective age group. RESULTS: The 875 consecutive HHF patients had a median age of 82 years [76-87 years]; 48.6 % were females. Betablocker and diuretic treatment did not change the incidence of endpoints. Inhibition of the renin-angiotensin system (RASi), when compared to no treatment, decreased the incidence of endpoints both at the 1-25 % and the > 25 % target dose level. Antagonists of the mineralocorticoid receptor (MRA), when compared to no treatment, decreased the secondary endpoint at the 1-25 % target dose level but not at the > 25 % target dose level. The relative treatment effect size of RASi or MRA corresponded between the age strata for both endpoints. CONCLUSION: Low-dose RASi and MRA had beneficial effects in these old HHF patients.


Subject(s)
Heart Failure , Renin-Angiotensin System , Aged, 80 and over , Aldosterone , Angiotensins , Female , Heart Failure/drug therapy , Hospitalization , Humans , Male , Renin , Stroke Volume
2.
Pharmacol Res ; 182: 106277, 2022 08.
Article in English | MEDLINE | ID: mdl-35662631

ABSTRACT

BACKGROUND: Pivotal randomized trials demonstrating efficacy, safety and good tolerance, of two new potassium binders (patiromer and sodium zirconium cyclosilicate) led to their recent approval. A major hurdle to the implementation of these potassium-binders is understanding how to integrate them safely and effectively into the long-term management of cardiovascular and kidney disease patients using renin angiotensin aldosterone system inhibitors (RAASi), the latter being prone to induce hyperkalaemia. METHODS: A multidisciplinary academic panel including nephrologists and cardiologists was convened to develop consensus therapeutic algorithm(s) aimed at optimizing the use of the two novel potassium binders (patiromer and sodium zirconium cyclosilicate) in stable adults who require treatment with RAASi and experience(d) hyperkalaemia in a non-emergent setting. RESULTS: Two dedicated pragmatic algorithms are proposed. The lowest intervention threshold (i.e. 5.1 mmol/L or greater) was the one used in the patiromer and sodium zirconium cyclosilicate) pivotal trials, both drugs being indicated to treat hyperkalaemia in a non -emergent setting. Acknowledging the heterogeneity across specialty guidelines in hyperkalaemia definition and thresholds to intervene when facing hyperkalaemia, we have been mindful to use soft language i.e. "it is to consider", not necessarily "to do". CONCLUSIONS: Providing the clinical community with pragmatic algorithms may help optimize the management of high-risk patients by avoiding the risks of both hyper and hypokalaemia and of suboptimal RAASi therapy.


Subject(s)
Heart Diseases , Heart Failure , Hyperkalemia , Renal Insufficiency, Chronic , Adult , Algorithms , Humans , Hyperkalemia/diagnosis , Hyperkalemia/drug therapy , Hypertension, Renal , Nephritis , Potassium , Renal Insufficiency, Chronic/drug therapy , Renin-Angiotensin System
3.
Int J Cardiol ; 258: 321-324, 2018 05 01.
Article in English | MEDLINE | ID: mdl-29459042

ABSTRACT

This report summarises three cases of Churg-Strauss syndrome (CSS) illustrating the diagnostic challenges associated with the cardiac manifestation of this disease. Here, we illustrate the role of cardiac magnetic resonance (CMR) for diagnosis and follow-up of CSS with a focus on new non-contrast T2-weighted imaging sequences for quantification of myocardial scar tissue and quantitative T2 mapping techniques, which allow the detection of myocardial edema.


Subject(s)
Churg-Strauss Syndrome/diagnostic imaging , Heart Diseases/diagnostic imaging , Magnetic Resonance Imaging, Cine/trends , Adult , Churg-Strauss Syndrome/complications , Female , Follow-Up Studies , Heart Diseases/complications , Humans , Male , Middle Aged
4.
Rev Med Suisse ; 10(432): 1197-200, 1202-3, 2014 May 28.
Article in French | MEDLINE | ID: mdl-24964529

ABSTRACT

Heart transplantation remains the treatment of choice in selected patients with severe heart failure (HF) despite optimal medical therapy. Since long-term survival after HTX is improving, there is a growing need for evidence-based strategies that reduce long-term mortality resulting from both immunological and non-immunological risk. This manuscript summarizes recommendations for treatment of transplant vasculopathy, malignancy after transplantation, and prevention of corticosteroid induced bone disease. Based on actual understanding of cardiovascular risk factors in the population, preservation of renal function, prevention and treatment of hyperlipidemia and diabetes, as well as blood pressure control play an important role in the long-term follow-up after heart transplantation.


Subject(s)
Cardiovascular Agents/therapeutic use , Heart Transplantation/rehabilitation , Immunosuppressive Agents/therapeutic use , Practice Guidelines as Topic , Contraindications , Drug-Related Side Effects and Adverse Reactions/epidemiology , Drug-Related Side Effects and Adverse Reactions/prevention & control , Graft Survival , Heart Failure/therapy , Heart Transplantation/mortality , Heart Transplantation/standards , Humans
5.
Rev Med Suisse ; 9(388): 1148-50, 1152-3, 2013 May 29.
Article in French | MEDLINE | ID: mdl-23789184

ABSTRACT

With the advent of new technologies, experience with long-term mechanical circulatory support (MCS) is rapidly growing. Candidates to MCS are selected based on concepts, strategies and classifications that are specific to this indication. As results drastically improve, supported by stronger scientific evidence, the trend is towards earlier implantation. An adequate pre-implant follow-up is mandatory in order to avoid missing the best window of opportunity for implantation. While on chronic support, the hemodynamic profile of patients with continuous-flow ventricular assist devices is unique and remarkably influenced by the hydration status. Optimal management of these patients from the pre-implant phase to the long-term support phase requires a multidisciplinary approach that is similar to that already long validated for organ transplantation.


Subject(s)
Assisted Circulation/trends , Cardiology/trends , Assisted Circulation/instrumentation , Assisted Circulation/legislation & jurisprudence , Assisted Circulation/methods , Cardiology/instrumentation , Cardiology/legislation & jurisprudence , Cardiology/methods , Coronary Circulation/physiology , Heart Diseases/therapy , Heart-Assist Devices , Humans , Long-Term Care , Models, Biological , Practice Guidelines as Topic , Time Factors
6.
Rev Med Suisse ; 9(368): 28, 30-5, 2013 Jan 09.
Article in French | MEDLINE | ID: mdl-23367700

ABSTRACT

The present review provides a selected choice of clinical research in the field of interventional cardiology, heart failure and cardiac imaging. We also focused on the new guidelines published by the European society of cardiology in 2012.


Subject(s)
Cardiology/trends , Administration, Oral , Anticoagulants/administration & dosage , Cardiac Imaging Techniques/methods , Cardiac Imaging Techniques/trends , Cardiac Surgical Procedures/methods , Cardiac Surgical Procedures/trends , Cardiology/methods , Drug Dosage Calculations , Heart Failure/therapy , Humans , Myocardial Infarction/classification , Myocardial Infarction/diagnosis , Stents , Terminology as Topic
7.
Rev Med Suisse ; 7(297): 1212-6, 2011 Jun 01.
Article in French | MEDLINE | ID: mdl-21717695

ABSTRACT

Heart transplantation (HTx) started in 1987 at two university hospitals (CHUV, HUG) in the western part of Switzerland, with 223 HTx performed at the CHUV until December 2010. Between 1987 and 2003, 106 HTx were realized at the HUG resulting in a total of 329 HTx in the western part of Switzerland. After the relocation of organ transplantation activity in the western part of Switzerland in 2003, the surgical part and the early postoperative care of HTx remained limited to the CHUV. However, every other HTx activity are pursued at the two university hospitals (CHUV, HUG). This article summarizes the actual protocols for selection and pre-transplant follow-up of HTx candidates in the western part of Switzerland, permitting a uniform structure of pretransplant follow-up in the western part of Switzerland.


Subject(s)
Heart Transplantation , Patient Selection , Preoperative Care , Algorithms , Follow-Up Studies , France , Heart Failure/surgery , Humans , Language , Preoperative Care/methods , Preoperative Care/standards , Preoperative Care/trends , Randomized Controlled Trials as Topic , Risk Factors , Switzerland , Waiting Lists
9.
Rev Med Suisse ; 6(252): 1211-7, 2010 Jun 09.
Article in French | MEDLINE | ID: mdl-20614757

ABSTRACT

Acute heart failure (AHF) is a frequent medical condition associated with a poor prognosis. Based on systolic blood pressure at presentation, patients with AHF can be classified into 5 clinical profiles enabling a more targeted use of standard medications including diuretics, vasodilators and inotropes. The most recent guidelines underline the importance of a rapid management and the favorable impact of heart failure programs, which reduce morbidity and mortality after an admission for AHF. New therapeutic perspectives include ultrafiltration, vasopressin and adenosine antagonists, relaxin and new inotropes such as istaroxime.


Subject(s)
Heart Failure/therapy , Acute Disease , Adenosine/antagonists & inhibitors , Algorithms , Cardiotonic Agents/therapeutic use , Diuretics/therapeutic use , Drug Therapy, Combination , Etiocholanolone/analogs & derivatives , Etiocholanolone/therapeutic use , Heart Failure/diagnosis , Heart Failure/drug therapy , Heart Failure/physiopathology , Hemodiafiltration , Humans , Oxygen Inhalation Therapy , Practice Guidelines as Topic , Prognosis , Relaxin/therapeutic use , Risk Factors , Treatment Outcome , Vasoconstrictor Agents/antagonists & inhibitors , Vasodilator Agents/therapeutic use , Vasopressins/antagonists & inhibitors
10.
Rev Med Suisse ; 5(205): 1214-6, 1218-20, 2009 May 27.
Article in French | MEDLINE | ID: mdl-19517754

ABSTRACT

Heart transplantation remains the best therapeutic option for the treatment of end-stage heart failure. However, good survival rates can be obtained only if patients are closely monitored, particularly for their immunosuppressive regimens. Currently, a triple-drug regimen usually based on calcineurin-inhibitors (cyclosporin A or tacrolimus), anti-proliferative agents and steroids is used in most recipients. New agents such as the mTOR inhibitors, a more recently developed class of immunosuppressive drugs, can also be used in some patients. The aim of this article is to review currently used immunosuppressive regimens after heart transplantation, and to propose some individualized options depending on specific patient characteristics and recent pharmacological developments in the field.


Subject(s)
Graft Rejection/prevention & control , Heart Transplantation , Immunosuppression Therapy/methods , Immunosuppressive Agents/administration & dosage , Monitoring, Immunologic/methods , T-Lymphocytes/drug effects , Chronic Disease , Clinical Trials as Topic , Cyclosporine/administration & dosage , Drug Therapy, Combination , Glucocorticoids/administration & dosage , Graft Survival/drug effects , Heart Failure/surgery , Humans , Meta-Analysis as Topic , Mycophenolic Acid/administration & dosage , Mycophenolic Acid/analogs & derivatives , Protein Kinases/drug effects , Randomized Controlled Trials as Topic , Sirolimus/administration & dosage , Survival Analysis , TOR Serine-Threonine Kinases , Tacrolimus/administration & dosage , Treatment Outcome
11.
J Heart Lung Transplant ; 28(5): 434-9, 2009 May.
Article in English | MEDLINE | ID: mdl-19416770

ABSTRACT

BACKGROUND: Peak oxygen uptake (peak Vo(2)) is an established integrative measurement of maximal exercise capacity in cardiovascular disease. After heart transplantation (HTx) peak Vo(2) remains reduced despite normal systolic left ventricular function, which highlights the relevance of diastolic function. In this study we aim to characterize the predictive significance of cardiac allograft diastolic function for peak Vo(2). METHODS: Peak Vo(2) was measured using a ramp protocol on a bicycle ergometer. Left ventricular (LV) diastolic function was assessed with tissue Doppler imaging sizing the velocity of the early (Ea) and late (Aa) apical movement of the mitral annulus, and conventional Doppler measuring early (E) and late (A) diastolic transmitral flow propagation. Correlation coefficients were calculated and linear regression models fitted. RESULTS: The post-transplant time interval of the 39 HTxs ranged from 0.4 to 20.1 years. The mean age of the recipients was 55 +/- 14 years and body mass index (BMI) was 25.4 +/- 3.9 kg/m(2). Mean LV ejection fraction was 62 +/- 4%, mean LV mass index 108 +/- 22 g/m(2) and mean peak Vo(2) 20.1 +/- 6.3 ml/kg/min. Peak Vo(2) was reduced in patients with more severe diastolic dysfunction (pseudonormal or restrictive transmitral inflow pattern), or when E/Ea was > or =10. Peak Vo(2) correlated with recipient age (r = -0.643, p < 0.001), peak heart rate (r = 0.616, p < 0.001) and BMI (r = -0.417, p = 0.008). Of all echocardiographic measurements, Ea (r = 0.561, p < 0.001) and Ea/Aa (r = 0.495, p = 0.002) correlated best. Multivariate analysis identified age, heart rate, BMI and Ea/Aa as independent predictors of peak Vo(2). CONCLUSIONS: Diastolic dysfunction is relevant for the limitation of maximal exercise capacity after HTx.


Subject(s)
Diastole/physiology , Exercise Test , Heart Failure/physiopathology , Heart Transplantation/physiology , Postoperative Complications/physiopathology , Ventricular Dysfunction, Left/physiopathology , Adult , Aged , Echocardiography, Doppler , Female , Heart Failure/diagnosis , Humans , Male , Middle Aged , Oxygen/blood , Postoperative Complications/diagnosis , Predictive Value of Tests , Prognosis , Systole/physiology , Ventricular Dysfunction, Left/diagnosis
12.
J Heart Lung Transplant ; 26(6): 622-9, 2007 Jun.
Article in English | MEDLINE | ID: mdl-17543787

ABSTRACT

BACKGROUND: Activation of the cytokine and the complement system is associated with disease progression in severe congestive heart failure (CHF). Magnitude and prognostic relevance of cytokine and complement activation remain uncertain in patients with moderate CHF. OBJECTIVES: Measurement of cytokine and complement activation in patients with moderate CHF and testing whether C-reactive protein (CRP) can serve as a surrogate marker of their activation, adding independent prognostic information when co-measured with B-type natriuretic peptide (BNP). METHODS: The 118 study participants were separated into three groups based on pre-determined CRP and BNP levels: Group I (n = 27; CRP > 5 mg/liter, BNP > or = 200 pg/ml); Group II (n = 46; CRP < or = 5 mg/liter, BNP > or = 200 pg/ml); and Group III (n = 45; CRP < or = 5 mg/liter, BNP < 200 pg/ml). RESULTS: Mortality was high in Group I (30%; log-rank p < 0.001) but low in Groups II and III (2% and 4%, respectively; log rank, p = 0.7). No differences were observed for left ventricular ejection fraction (LVEF) and left ventricular end-diastolic diameter (LVEDD) between Groups I and II (31 +/- 16 vs 32 +/- 14% and 66 +/- 16 vs 65 +/- 11 mm, respectively), whereas in Group III LVEF was higher (42 +/- 17%, p = 0.002) with smaller LVEDD (57 +/- 13 mm, p = 0.012). Cytokine sCD14 and tumor necrosis factor (TNF)-alpha levels were not different between the three groups. However, interleukin-6 levels (9.75 +/- 8.17 pg/ml, p = 0.001) and the terminal complement complex C5b-9 (109.9 +/- 68 ng/ml; p = 0.04) were elevated in Group I, both correlating with CRP (interleukin-6: r = 0.5, p < 0.001; C5b-9: r = 0.41, p = 0.001). CONCLUSIONS: CRP may be used as a surrogate parameter for interleukin-6 and complement activation in moderate CHF. CRP in combination with BNP identifies a high-risk group with a tendency for poor outcome not discriminated by cardiac function.


Subject(s)
Complement System Proteins/physiology , Cytokines/blood , Heart Failure/physiopathology , Adult , Aged , Biomarkers/blood , Bone Morphogenetic Proteins/blood , C-Reactive Protein/metabolism , Chronic Disease , Disease Progression , Female , Follow-Up Studies , Heart Diseases/classification , Heart Failure/blood , Humans , Male , Middle Aged , Time Factors
13.
Am J Transplant ; 6(4): 775-82, 2006 Apr.
Article in English | MEDLINE | ID: mdl-16539635

ABSTRACT

Previous studies demonstrated that impaired left ventricular (LV) relaxation in cardiac allografts limits exercise tolerance post-transplant despite preserved systolic ejection fraction (EF). This study tested in human cardiac allografts whether the isovolumic relaxation time (IVRT), which provides the basis for most of diastolic LV filling, relates with gene expression of regulatory proteins of calcium homeostasis or cardiac matrix proteins. Gene expression was studied in 31 heart transplant recipients (25 male, 6 female) 13-83 months post-transplant with LVEF >50%, LV end-diastolic pressure <20 mmHg, normal LV mass index and without allograft rejection or significant cardiac pathology. IVRT related with the other diastolic parameters e-wave velocity (r = -0.46; p = 0.01), e/a-wave ratio (r = -0.5; p < 0.01) but not with heart frequency (r = -0.16; p = 0.4). No relation of IVRT was observed for immunosuppression, mean rejection grade or other medication. IVRT was not related with gene expression of desmin, collagen I, phospholamban, the Na+-Ca2+ exchanger, the ryanodine receptor or interstitial fibrosis but correlated inversely with SERCA2a (r = -0.48; p = 0.02). Prolonged IVRT is associated with decreased SERCA2a expression in cardiac allografts without significant other pathology. Similar observations in non-transplanted patients with diastolic failure suggest that decreased SERCA2a expression is an important common pathomechanism.


Subject(s)
Calcium-Transporting ATPases/genetics , Diastole/genetics , Down-Regulation/genetics , Heart Transplantation , Ventricular Dysfunction, Left/diagnosis , Adult , Aged , Calcium-Binding Proteins/genetics , Collagen Type I/genetics , Desmin/genetics , Exercise Tolerance/genetics , Gene Expression , Humans , Male , Middle Aged , Myocardium/metabolism , Myocardium/pathology , Ryanodine Receptor Calcium Release Channel/genetics , Sarcoplasmic Reticulum Calcium-Transporting ATPases , Sodium-Calcium Exchanger/genetics , Ventricular Dysfunction, Left/genetics
14.
Eur J Heart Fail ; 7(6): 1057-8, 2005 Oct.
Article in English | MEDLINE | ID: mdl-16227144

ABSTRACT

Pre-eclampsia occurs in 2-5% of pregnancies of healthy women. Here, we present a rare case of pre-eclampsia with overt acute heart failure, which was the primary manifestation of systemic lupus erythematosus with cardiac and renal involvement.


Subject(s)
Heart Failure/diagnosis , Infant, Premature , Lupus Erythematosus, Systemic/diagnosis , Pre-Eclampsia/diagnosis , Pregnancy Outcome , Acute Disease , Adult , Biopsy, Needle , Diagnosis, Differential , Echocardiography, Doppler , Female , Humans , Immunohistochemistry , Infant, Newborn , Maternal Age , Parity , Postpartum Period , Pregnancy , Risk Assessment , Severity of Illness Index
16.
Gene Ther ; 7(3): 232-40, 2000 Feb.
Article in English | MEDLINE | ID: mdl-10694800

ABSTRACT

Catheter-based percutaneous transluminal gene delivery (PTGD) into the coronary artery still falls behind the expectations of an efficient myocardial gene delivery system. In this study gene delivery was applied by selective pressure-regulated retroinfusion through the coronary veins to prolong adhesion of replication defective adenovirus within the targeted myocardium. Adenoviral vectors consisted either of luciferase (Ad.rsv-Luc) or beta-galactosidase (Ad.rsv-betaGal) reporter gene under control of an unspecific promotor derived from the Rous sarcoma virus (RSV). In this pig model, selective retrograde gene delivery into the anterior cardiac vein during a brief period of ischemia substantially increased reporter gene expression in the targeted myocardium (LAD region) compared with antegrade delivery as a control. Repeated retrograde delivery during two periods of brief ischemia resulted in a more homogeneous transmural expression predominantly observed in cardiomyocytes (X-gal-staining). In the nontargeted myocardium (CX region) there was no evidence for adenoviral transfection. From our data we infer that selective pressure-regulated retroinfusion is a promising approach for efficient percutaneous transluminal gene delivery to the myocardium. Gene Therapy (2000) 7, 232-240.


Subject(s)
Adenoviridae/genetics , Coronary Vessels/chemistry , Gene Transfer Techniques , Genetic Vectors/genetics , Myocardium/chemistry , Animals , Immunohistochemistry , Infusions, Intravenous , Myocardial Ischemia/genetics , Myocardium/metabolism , Polymerase Chain Reaction , Swine , Time Factors , Transfection/genetics , beta-Galactosidase/metabolism
17.
Circulation ; 100(2): 155-63, 1999 Jul 13.
Article in English | MEDLINE | ID: mdl-10402445

ABSTRACT

BACKGROUND: Left ventricular diastolic dysfunction is a major cause of cardiac allograft failure. Multimeric L-type calcium channels (alpha1-, alpha2/delta-, and beta-subunits) are essential for excitation/contraction coupling in the heart. Their gene expression was studied in allografts that developed diastolic heart failure. METHODS AND RESULTS: mRNA levels of calcium channel subunits were measured by competitive reverse transcriptase-polymerase chain reaction in microbiopsy samples from the interventricular septum. Size and tissue variabilities between biopsy samples were assessed by determination of cardiac calsequestrin mRNA levels. In the cardiac allografts studied, mRNA levels in microbiopsy samples were considered to represent left ventricular gene expression, because septal and left ventricular gene expression in Northern blots was equivalent, and left ventricles contracted homogeneously. Biopsy samples (n=72) were taken from allografts with normal left ventricular end-diastolic pressure (LVEDP; 8 to 13 mm Hg; n=30), moderately elevated LVEDP (14 to 18 mm Hg; n=26), and elevated LVEDP (19 to 28 mm Hg; n=16). Increased LVEDP was related to slowed diastolic relaxation determined by the time constant tau (r2=0.86), whereas systolic performance (dP/dt; ejection fraction) was preserved. With increasing LVEDP, mRNA levels of the pore-forming alpha1c-subunit (n=15) and of the regulatory alpha2/delta-subunit (n=17) remained unchanged but decreased exponentially (r2=-0.83) for the regulatory beta-subunit (n=40). Compared with cardiac allografts with normal LVEDP (n=15), beta-subunit mRNA level was reduced by 75% at elevated LVEDP (n=9; P=0.012). In an explanted, diastolically failing cardiac allograft, beta-subunit expression was reduced correspondingly by 72% and 76% on the mRNA level in septal and left ventricular myocardium and by 80% on the protein level. CONCLUSIONS: The downregulated expression of the calcium channel beta-subunit might contribute to altered calcium handling in diastolically failing cardiac allografts.


Subject(s)
Calcium Channels/metabolism , Cardiac Output, Low/metabolism , Heart Transplantation , Myocardium/metabolism , Postoperative Complications , Adult , Aged , Calcium Channels/genetics , Calcium Channels, L-Type , Calsequestrin/genetics , Diastole , Female , Graft Rejection/metabolism , Heart Septum/metabolism , Heart Ventricles , Humans , Male , Middle Aged , Protein Isoforms/genetics , Protein Isoforms/metabolism , RNA, Messenger/metabolism , Reverse Transcriptase Polymerase Chain Reaction
18.
EMBO J ; 18(9): 2323-9, 1999 May 04.
Article in English | MEDLINE | ID: mdl-10228147

ABSTRACT

Cardiac pacemaking is produced by the slow diastolic depolarization phase of the action potential. The hyperpolarization-activated cation current (If) forms an important part of the pacemaker depolarization and consists of two kinetic components (fast and slow). Recently, three full-length cDNAs encoding hyperpolarization-activated and cyclic nucleotide-gated cation channels (HCN1-3) have been cloned from mouse brain. To elucidate the molecular identity of cardiac pacemaker channels, we screened a human heart cDNA library using a highly conserved neuronal HCN channel segment and identified two cDNAs encoding HCN channels. The hHCN2 cDNA codes for a protein of 889 amino acids. The HCN2 gene is localized on human chromosome 19p13.3 and contains eight exons spanning approximately 27 kb. The second cDNA, designated hHCN4, codes for a protein of 1203 amino acids. Northern blot and PCR analyses showed that both hHCN2 and hHCN4 are expressed in heart ventricle and atrium. When expressed in HEK 293 cells, either cDNA gives rise to hyperpolarization-activated cation currents with the hallmark features of native If. hHCN2 and hHCN4 currents differ profoundly from each other in their activation kinetics, being fast and slow, respectively. We thus conclude that hHCN2 and hHCN4 may underlie the fast and slow component of cardiac If, respectively.


Subject(s)
Biological Clocks , Ion Channel Gating , Ion Channels/metabolism , Muscle Proteins , Myocardium/metabolism , Chromosomes, Human, Pair 19 , Cloning, Molecular , Cyclic Nucleotide-Gated Cation Channels , Electrophysiology , Heart Atria , Heart Ventricles , Humans , Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels , Ion Channels/genetics , Kinetics , Molecular Sequence Data , Potassium Channels , Sequence Analysis, DNA , Tissue Distribution
19.
J Mol Cell Cardiol ; 31(1): 283-96, 1999 Jan.
Article in English | MEDLINE | ID: mdl-10072735

ABSTRACT

The purpose of the present study was to investigate the expression and functional relevance of sarcolemmal L-type Ca2+-channels in failing and non-failing human myocardium. The protein expression of sarcolemmal L-type Ca2+-channels was determined with 3H-(+)-PN 200-110-binding experiments and Western blot analysis using a specific antibody against the alpha1-subunit in membrane preparations of ventricular and atrial myocardium from both failing (n = 15) and non-failing hearts (n = 8). The gene expression of the ion conducting pore of the L-type Ca2+-channel was examined with Northern blot technique in human failing and non-failing RNA. For normalization the RNA expression of calsequestrin was used. In electrically driven ventricular papillary muscle strips and auricular trabeculae, the responses to nifedipine and Ca2+ as parameters of myocardial function were studied. The protein expression as measured by 3H-(+)-PN 200-110-binding (Bmax) and Western Blot analysis with calsequestrin as reference was similar in left ventricular failing and non-failing myocardium. However, both were reduced in atrial compared to ventricular tissue in failing and non-failing hearts. The KD remained unchanged. Calsequestrin levels were unaltered in failing and non-failing hearts. The gene expression of the alpha1-subunit was similar in human failing and non-failing hearts. The L-type Ca2+-channel antagonist nifedipine reduced force of contraction with the same potency and efficiency in ventricular failing and non-failing myocardium. In contrast, the potency of nifedipine was higher in atrial than in ventricular tissue. Consistently, atrial myocardium from patients with dilated cardiomyopathy was more sensitive towards Ca2+ than those of the control group. In conclusion, the altered Ca2+-homeostasis in failing human myocardium may be less due to changes in sarcolemmal L-type Ca2+-channel expression or function than due to an altered intracellular Ca2+-handling.


Subject(s)
Calcium Channels/physiology , Myocardium/metabolism , Adolescent , Adult , Aged , Binding Sites/physiology , Blotting, Northern , Blotting, Western , Calcium/metabolism , Calcium Channel Blockers/metabolism , Calcium Channels, L-Type , Calsequestrin/pharmacology , Cardiomyopathy, Dilated , Dihydropyridines/analysis , Dihydropyridines/metabolism , Dose-Response Relationship, Drug , Female , Heart/physiology , Heart Failure , Humans , Male , Middle Aged , Nifedipine/pharmacology , Tissue Distribution
20.
Circulation ; 98(10): 969-76, 1998 Sep 08.
Article in English | MEDLINE | ID: mdl-9737516

ABSTRACT

BACKGROUND: The role of the L-type calcium channel in human heart failure is unclear, on the basis of previous whole-cell recordings. METHODS AND RESULTS: We investigated the properties of L-type calcium channels in left ventricular myocytes isolated from nonfailing donor hearts (n= 16 cells) or failing hearts of transplant recipients with dilated (n=9) or ischemic (n=7) cardiomyopathy. The single-channel recording technique was used (70 mmol/L Ba2+). Peak average currents were significantly enhanced in heart failure (38.2+/-9.3 fA) versus nonfailing control hearts (13.2+/-4.5 fA, P=0.02) because of an elevation of channel availability (55.9+/-6.7% versus 26.4+/-5.3%, P=0.001) and open probability within active sweeps (7.36+/-1.51% versus 3.18+/-1.33%, P=0.04). These differences closely resembled the effects of a cAMP-dependent stimulation with 8-Br-cAMP (n= 11). Kinetic analysis of the slow gating shows that channels from failing hearts remain available for a longer time, suggesting a defect in the dephosphorylation. Indeed, the phosphatase inhibitor okadaic acid was unable to stimulate channel activity in myocytes from failing hearts (n=5). Expression of calcium channel subunits was measured by Northern blot analysis. Expression of alpha1c- and beta-subunits was unaltered. Whole-cell current measurements did not reveal an increase of current density in heart failure. CONCLUSIONS: Individual L-type calcium channels are fundamentally affected in severe human heart failure. This is probably important for the impairment of cardiac excitation-contraction coupling.


Subject(s)
Calcium Channels/physiology , Cardiomyopathies/physiopathology , Cardiomyopathy, Dilated/physiopathology , Heart/physiology , Myocardial Ischemia/physiopathology , 8-Bromo Cyclic Adenosine Monophosphate/pharmacology , Calcium Channels, L-Type , Cells, Cultured , Cyclic AMP/physiology , Heart/physiopathology , Heart Ventricles , Humans , Ion Channel Gating , Kinetics , Membrane Potentials , Probability , Reference Values , Time Factors
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