Search results for "HEART"
showing 10 items of 3201 documents
Induction of apoptosis in cardiac myocytes by an A3 adenosine receptor agonist.
1998
The effects of the selective adenosine (ADO) A3 receptor agonist IB-MECA (N6-(3-iodobenzyl)adenosine-5'-N-methylcarboxamide) on cultured newborn rat cardiomyocytes were examined in comparison with ADO, the ADO A1 receptor-selective agonist R-PIA (N6-R-phenylisopropyladenosine), or the ADO A3 selective antagonist MRS 1191 (3-ethyl-5-benzyl-2-methyl-6-phenyl-4-phenylethynyl-1, 4-(+/-)-dihydropyridine-3,5 dicarboxylate), using digital image analysis of Feulgen-stained nuclei. At high concentration, IB-MECA (/=10 microM ) and ADO (200 microM) induced apoptosis; however, R-PIA or MRS 1191 did not have any detectable effects on cardiac cells. In addition, DNA breaks in cardiomyocytes undergoing a…
Glycopyrronium bromide blocks differentially responses mediated by muscarinic receptor subtypes.
1993
To analyse the potency of glycopyrronium bromide in blocking responses mediated via subtypes of muscarinic receptors in vitro, we tried to determine its equilibrium dissociation constants at prejunctional muscarinic receptors inhibiting the twitch response of rabbit vas deferens (presumed M1 type), at M2 (paced at left atria), M3 (guinea pig ileum) muscarinic receptor subtypes and at the muscarinic receptor of the rabbit iris sphincter (not M1-M4, not m5). Glycopyrronium bromide shifted to the right the curve for inhibition of the twitch response induced by the agonist McN-A-343, and the methacholine-induced curves for inhibition of rat atrial contraction, and for tonic contraction of guine…
Induction of Apoptosis in Rat Cardiocytes by A3 Adenosine Receptor Activation and Its Suppression by Isoproterenol
2000
The purpose of the present study was to investigate the mechanisms involved in the induction of apoptosis in newborn cultured cardiomyocytes by activation of adenosine (ADO) A3 receptors and to examine the protective effects of beta-adrenoceptors. The selective agonist for A3 ADO receptors Cl-IB-MECA (2-chloro-N6-iodobenzyl-5-N-methylcarboxamidoadenosine) and the antagonist MRS1523 (5-propyl-2-ethyl-4-propyl-3-(ethylsulfanylcarbonyl)-6-phenylpy rid ine-5-carboxylate) were used. High concentrations of the Cl-IB-MECA (or = 10 microM) agonist induced morphological modifications of myogenic cells, such as rounding and retraction of cell body and dissolution of contractile filaments, followed by…
Desensitization of inhibitory prejunctional alpha 2-adrenoceptors and putative imidazoline receptors on rabbit heart sympathetic nerves.
1993
To find out whether sympathetic nerves of the rabbit heart possess pharmacologically relevant prejunctional imidazoline receptors different from α-autoreceptors, the inhibition by oxymetazoline, aganodine and BDF 6143 (4-chloro-2-[2-imidazoline-2-ylamino]-isoindoline hydrochloride) of endogenous noradrenaline overflow evoked by stimulation of extrinsic postganglionic sympathetic nerves (0.66 Hz, 80 pulses) was investigated. In addition we wanted to find out whether either type of these prejunctional receptors undergoes desensitization upon pre-exposure to respective agonists. The α2-adrenoceptor agonist oxymetazoline inhibited the evoked noradrenaline overflow (2.9 nmol/l, IC50; about 90010…
LED-bed therapy of cardiovascular disorders: a volunteer study
2020
Studies of the physiological response of human half-body illumination by a specially designed bed comprising large number of LEDs emitting in the red and near infrared spectral range were carried out in a group of 32 volunteers comprising healthy subjects and hypertension patients. Blood pressure, heart rate and arterial blood oxygen saturation, as well as the bed surface temperature were continuously monitored during the measurement sessions with and without aluminum foil cover on the bed surface. None of the volunteers exhibited any notable changes in the heart rate and blood oxygenation during the procedures. The LightStim LED-bed session did not produce changes of arterial pressure in n…
Effects of amsacrine (m-AMSA), a new aminoacridine antitumor drug, on the rabbit heart.
1983
There is emerging clinical evidence that amsacrine (m-AMSA) administration may be associated with cardiotoxic effects such as severe, even fatal, ventricular arrhythmias and impairment of the inotropic performance of the heart. Information on the cardiac effects of m-AMSA in animals is scanty. Studies on mice, dogs, and monkeys have not evidenced the cardiotoxicity of the compound. The data presented in this paper show that m-AMSA causes acute ECG alterations in normal rabbits and a dose-related negative inotropic effect on the isolated rabbit heart, suggesting that this species may be a useful model for the study of the cardiac actions of this antiblastic.
Application of C1-Esterase Inhibitor During Reperfusion of Ischemic Myocardium
2001
Background—Complement activation during reperfusion of ischemic myocardium augments myocardial injury, and complement inhibition with C1-esterase inhibitor (C1-INH) at the time of reperfusion exerts marked cardioprotective effects in experimental studies. Application of C1-INH in newborns, however, was recently reported to have dangerous and even lethal side effects. This study addresses the essential role of dosage in studies using C1-INH.Methods and Results—Cardioprotection by C1-INH was examined in a pig model with 60 minutes of coronary occlusion followed by 120 minutes of reperfusion. C1-INH was administered intravenously 5 to 10 minutes before coronary reperfusion without heparin at a…
New insights into the role of matrix metalloproteinases in heart angiogenesis induced by exercise
2008
Angiogenesis induced by exercise has been observed in both cardiac and skeletal muscle and plays a fundamental role in maintaining tissue function adequate to the increase in metabolic requests. Mechanical and haemodynamic forces are strong starters of angiogenic process via regulation of secondary mediators such as vascular endothelial growth factor (VEGF). A crucial step of vessel sprouting is the degradation of the basement membrane and remodelling of the extracellular matrix (ECM) by matrix metalloproteinases (MMPs). It has long been accepted that MMPs are involved in the angiogenesis, but the exact mechanisms are not well characterized. Cryptic fragments and neo-epitopes released by pr…
Endothelial Leptin Receptor Deletion Promotes Cardiac Autophagy and Angiogenesis Following Pressure Overload by Suppressing Akt/mTOR Signaling.
2019
Background: Cardiac remodeling is modulated by overnutrition or starvation. The adipokine leptin mediates energy balance between adipose tissue and brain. Leptin and its receptors are expressed in the heart. Methods and Results: To examine the importance of endothelial leptin signaling in cardiac hypertrophy, transverse aortic constriction was used in mice with inducible endothelium-specific deletion of leptin receptors (End.LepR-KO) or littermate controls (End.LepR-WT). End.LepR-KO was associated with improved left ventricular function (fractional shortening, 28.4% versus 18.8%; P =0.0114), reduced left ventricular dilation (end-systolic inner left ventricular diameter, 3.59 versus 4.08 m…
A recommended practical approach to the management of target therapy and angiogenesis inhibitors cardiotoxicity: an opinion paper of the working grou…
2016
The US National Cancer Institute estimates that cardiotoxicity (CTX) from target therapy refers mostly to four groups of drugs: epidermal growth factor receptor 2 inhibitors, angiogenic inhibitors, directed Abelson murine leukemia viral oncogene homolog inhibitors, and proteasome inhibitors. The main cardiotoxic side-effects related to antiepidermal growth factor receptor 2 therapy are left ventricular systolic dysfunction and heart failure. Angiogenesis inhibitors are associated with hypertension, left ventricular dysfunction/heart failure, myocardial ischemia, QT prolongation, and thrombosis. Moreover, other agents may be related to CTX induced by treatment. In this study, we review the g…