Distribution and function of sodium channel subtypes in human atrial myocardium.

Voltage-gated sodium channels composed of a pore-forming α subunit and auxiliary β subunits are responsible for the upstroke of the action potential in cardiac muscle. However, their localization and expression patterns in human myocardium have not yet been clearly defined. We used immunohistochemical methods to define the level of expression and the subcellular localization of sodium channel α and β subunits in human atrial myocytes.

A collagen α2(I) mutation impairs healing after experimental myocardial infarction.

Collagen breakdown and de novo synthesis are important processes during early wound healing after myocardial infarction (MI). We tested the hypothesis that collagen I, the main constituent of the extracellular matrix, affects wound healing after MI. The osteogenesis imperfecta mouse (OIM), lacking procollagen-α2(I) expression, represents a model of the type III form of the disease in humans.

Long-term reduction of mortality in the 4-year follow up of tirofiban therapy in elective percutaneous coronary interventions (TOPSTAR) trial.

Background: TOPSTAR was a randomized, placebo-controlled trial studying the effects of adding the glycoprotein IIb/IIIa inhibitor tirofiban to conventional treatment with aspirin and clopidogrel in patients undergoing elective percutaneous coronary interventions (PCI). TOPSTAR demonstrated a lower periprocedural troponin release and a reduced 6-month mortality risk following PCI. The present study analyzed the corresponding long-term effects.

Protective effects of sphingosine-1-phosphate receptor agonist treatment after myocardial ischaemia-reperfusion.

Aims: Several experimental studies have demonstrated protection against cardiac ischaemia-reperfusion injury achieved by pre-treatment with exogenous sphingosine-1-phosphate (S1P). We tested the hypothesis that pharmacological S1P receptor agonists improve recovery of function when applied with reperfusion.

Methods And Results: Isolated rat cardiomyocytes were stimulated with exogenous S1P, the selective S1P1 receptor agonist SEW2871, or the S1P1/3 receptor agonist FTY720.

Evidence for a negative inotropic effect of obesity in human myocardium?

Objective: The present study was performed as an attempt to analyze the relationship between body weight and human myocardial performance. As overweight is frequently associated with hypertension, stenosis of epimyocardial coronary arteries and other factors that influence myocardial performance, the experimental model of isolated human atrial myocardium was selected. Atrial contractile performance does neither depend on the extent of stenosis of epicardial coronary arteries nor on the degree of hypertension and its secondary pathology.

Lack of iNOS impairs endothelial function in endothelin-1 transgenic mice.

Background: Endothelin-1 (ET-1) is one of the most potent biologic vasoconstrictors. Nevertheless, transgenic mice overexpressing ET-1 exhibit normal blood pressure. We hypothesized that in states of ET-1 overproduction, the lack of counterregulatory mediators such as nitric oxide (NO), produced by the inducible NO synthase (iNOS), may critically impair endothelial function and may result in blood pressure elevation.

Multi-slice cardiac computed tomography reveals anomalous origin of the right coronary artery between the great arteries.

We report a case of a 72-year-old man whose multi-slice cardiac computed tomography revealed an anomalous origin of the right coronary artery between the great arteries.

Conditional neuronal nitric oxide synthase overexpression impairs myocardial contractility.

The role of the neuronal NO synthase (nNOS or NOS1) enzyme in the control of cardiac function still remains unclear. Results from nNOS(-/-) mice or from pharmacological inhibition of nNOS are contradictory and do not pay tribute to the fact that probably spatial confinement of the nNOS enzyme is of major importance. We hypothesize that the close proximity of nNOS and certain effector molecules like L-type Ca(2+)-channels has an impact on myocardial contractility.

The estrogen receptor-alpha agonist 16alpha-LE2 inhibits cardiac hypertrophy and improves hemodynamic function in estrogen-deficient spontaneously hypertensive rats.

Objective: Cardiac mass increases with age and with declining estradiol serum levels in postmenopausal women. Although the non-selective estrogen receptor-alpha and -beta agonist 17beta-estradiol attenuates cardiac hypertrophy in animal models and in observational studies, it remains unknown whether activation of a specific estrogen receptor subtype (ERalpha or ERbeta) might give similar or divergent results. Therefore, we analyzed myocardial hypertrophy as well as cardiac function and gene expression in ovariectomized, spontaneously hypertensive rats (SHR) treated with the subtype-selective ERalpha agonist 16alpha-LE2 or 17beta-estradiol.

Variable extent of clopidogrel responsiveness in patients after coronary stenting.

Clopidogrel is an effective and specific inhibitor of ADP-induced platelet aggregation. After metabolic activation, the active clopidogrel metabolite irreversibly impairs the human platelet P2Y12 ADP receptor. Gialpha-protein activation and inhibition of vasodilator-stimulated phosphoprotein (VASP) phosphorylation are two key elements of the P2Y12 receptor pathway suitable for quantitation of clopidogrel effects.

Administration of testosterone is associated with a reduced susceptibility to myocardial ischemia.

This study investigated the impact of testosterone on myocardial ischemia-reperfusion injury and corresponding intracellular calcium ([Ca2+]i) metabolism. Nonorchiectomized mature male Wistar rats were randomly assigned to placebo, a single dose of testosterone undecanoate, or 5alpha-dihydrotestosterone. In a further series, orchiectomized rats were treated with placebo.

Cytokine response after percutaneous coronary intervention in stable angina: effect of selective glycoprotein IIb/IIIa receptor antagonism.

Background: It is unclear whether modulation of inflammatory markers by glycoprotein IIb/IIIa receptor inhibition after percutaneous coronary intervention (PCI) is caused by an interaction with the alpha(v)beta3 and alpha(M)beta2 receptor or it correlates with ischemic events during PCI. This study investigates the inflammatory profile after elective, nonacute PCI and whether and how administration of the glycoprotein IIb/IIIa receptor antagonist tirofiban modulates the postinterventional inflammatory myocardial response.

Methods: The time course of inflammatory parameters (C-reactive protein [CRP], interleukin-1 [IL-1], interleukin-6 [IL-6], and tumor necrosis factor alpha [TNF-alpha]) of patients receiving peri- and postinterventional placebo (n = 46) or tirofiban infusion (n = 50) was analyzed by use of enzyme-linked immuno assays.

Cannabinoids acting on CB1 receptors decrease contractile performance in human atrial muscle.

Cannabinoids elicit hypotension mainly via activated CB(1) receptors and show complex cardiovascular actions. Effects on human heart muscle have not been studied yet. Isolated human atrial heart muscle preparations were stimulated by electrical field with 1 Hz to contract isometrically at optimal length and were challenged with the endogenous cannabinoid arachidonyl ethanolamide (anandamide), the metabolically stable analogue R-methanandamide, and the potent synthetic CB(1) receptor agonist HU-210.

Increased myocardial oxygen consumption by TNF-alpha is mediated by a sphingosine signaling pathway.

The present study investigated the effect of tumor necrosis factor (TNF)-alpha on myocardial energy metabolism as estimated by myocardial oxygen consumption (MVo(2)). MVo(2) of electrically stimulated isolated trabeculae of right ventricular Wistar rat myocardium was analyzed using a Clark-type oxygen probe. After the initial data collection in the absence of TNF-alpha, measurements were repeated after TNF-alpha stimulation.

Functional properties and [Ca(2+)](i) metabolism of creatine kinase--KO mice myocardium.

One major function of the creatine kinase system is to maintain energy demand of myofibrillar contraction processes. Loss of the CK-system led to adaptations in skeletal muscle. To analyze the impact on myocardial function contractile parameters and intracellular calcium metabolism of transgenic mice lacking mitochondrial CK (ScCKmit(-/-)) alone or both mitochondrial and cytoplasmic ScCK (CK(-/-)) were investigated compared to wild type at various workload conditions using isolated intact muscle fibers.

Effect of additional temporary glycoprotein IIb/IIIa receptor inhibition on troponin release in elective percutaneous coronary interventions after pretreatment with aspirin and clopidogrel (TOPSTAR trial).

Objectives: The Troponin in Planned PTCA/Stent Implantation With or Without Administration of the Glycoprotein IIb/IIIa Receptor Antagonist Tirofiban (TOPSTAR) trial investigated: 1) the amount of troponin T (TnT) release after nonacute, elective percutaneous coronary intervention (PCI) in patients pretreated with aspirin and clopidogrel; and 2) the effect of additional glycoprotein (GP) IIb/IIIa receptor inhibiton on postinterventional TnT release.

Background: No data are available yet as to whether additional administration of a GP IIb/IIIa receptor antagonist might be beneficial in patients undergoing elective PCI already pretreated with aspirin and clopidogrel.

Methods: After bolus application of the study medication (tirofiban [T] or placebo [P]), PCI was performed followed by an 18-h continuous infusion of T/P.