The contractile response and myocardial content of Gi-proteins were examined in cardiac preparations from explanted hearts of four different patients with end-stage heart failure. Three patients had idiopathic dilated cardiomyopathy and one patient had inflammatory heart disease. Preparations from patients with idiopathic dilated cardiomyopathy showed reduced contractile response to the ...

Although a progressive reduction in left ventricular contractility during sustained left stellate ganglion stimulation has been well documented, there have been no reports on the contractile state after nerve stimulation. Left ventricular contractility after cessation of 60 min of electrical (10 V. 10 Hz. 1 msec) left stellate ganglion stimulation ...

Effects of endurance swimming training on myocardial contractility and left ventricular myosin isoenzymes were examined in diabetic rats. A diabetic condition was induced in 15-week-old male Wistar rats, by intravenous injection of streptozotocin (50 mg/kg). Swimming training was carried out for five to six weeks (90 min/day, 6 days/week). In ...

Histamine is known to act as a direct stimulator. In the heart, two types of histamine receptors are present: H1- and H2-receptors. H2-receptors cause an increase in heart rate and contractility as well as coronary vasodilatation, whereas H1-receptors mediate chronotropic effects and coronary vasoconstriction. During anaphylactic states, histamine is released ...

Verapamil is an effective and relatively-safe antihypertensive drug. Serious adverse effects are uncommon and mainly have been related to the depression of cardiac contractility and conduction, especially when the drug is combined with beta-blocking agents. We report a case in which myocardial infarction coincided with the introduction of captopril and ...

Recovery from the cardiac depressant effects of enflurane and halothane was examined in the dog heart-lung preparation (HLP) and in right ventricular muscle isolated from guinea pig hearts. In the HLP. recovery was studied under two conditions: (1) After a two-hour exposure to anesthetic concentrations increasing from 0.36 to 1.2 ...

Experiments were conducted in anesthetized dogs to determine the mechanism primarily responsible for the increase in myocardial contractile function during intravenous infusion of nicotine. Myocardial function was assessed regionally by measuring segment shortening using ultrasonic dimension gauges. The role of cardiac neural stimulation in the absence of direct effects of ...

The ability of the left ventricle to modulate its performance is an important and integral component in the cardiovascular system's adaptive response to increased workload. Abnormalities in ventricular contractility can blunt this response and thus significantly limit the patient's functional capacity. The accurate determination and quantitation of cardiac contractility and ...

Rats were fed a diet containing beta-guanidinopropionic acid (GP), an inhibitor of creatine transport. After 6 to 8 weeks of feeding the myocardial creatine (Cr) and phosphocreatine (PCr) stores were severely depleted while ATP content was normal. Hearts of GP-treated rats perfused according to Neely's working heart model revealed clear ...

Isolated perfused rat hearts were used to compare the effects of the synthetic neuropeptide Y (NPY) and 4-norleucine-NPY on cardiac function. Each peptide exhibited both negative inotropic and chronotropic effects, and also caused coronary vasoconstriction leading to a reduction in coronary flow. A comparison of the IC50 values from dose-response ...

The present study was designed to elucidate metabolic factors related to reoxygenation-induced recovery of cardiac contractile force after a period of hypoxia, from the view point of energy metabolism in the myocardium. Rabbit hearts were perfused for 20 mins under various degrees of hypoxic conditions, followed by 45 mins of ...

Control of the performance of the heart can now be understood in terms of three paradigms: beat-to-beat, length-dependent regulation (Starling's Law of the Heart); short term regulation by biochemical changes within the cardiac cell (excitation-contraction coupling, myocardial contractility); and long term regulation by altered gene expression (molecular biology). The latter ...

The effects of Bay K 8644, aortic constriction, and a placebo on regional myocardial blood flows (RMBFs) and contractile function (RCF) were compared in three groups of open-chest anesthetized dogs during coronary stenosis. Bay K 8644 was investigated in two doses: 0.1 micrograms/kg, which exhibited no systemic hemodynamic effect, and ...

Calcium channel blockers (CCBs) may produce profound myocardial depression. Glucagon antagonized verapamil-induced hypotension and bradycardia in rats; however, glucagon's ability to antagonize other CCBs is unexplored. This study determined: a) if glucagon reverses verapamil-induced depression by a direct cardiac effect, b) if myocardial depression induced by diltiazem and nifedipine (representing ...

Clinical trials in patients with dilated cardiomyopathy (DCM) have shown a wide disparity in the hemodynamic responses to positive inotropic therapy. In addition, the response of the failing left ventricle to positive inotropic agents reflects the net interaction of multiple factors, including the magnitude of contractile abnormality and compensatory mechanisms. ...

Lower intracellular Na+ during beta-adrenergic stimulation provides an increased driving force for Na-Ca exchange, which might attenuate the inotropic response. Since (1) Na+ reduction is coupled to K+ uptake, and (2) K+ uptake lags behind the positive inotropic response to isoproterenol, we could examine the effect of Na-Ca exchange by ...

Carnitine, certain of its derivatives, and the amino acid metabolite, taurine, when administered independently in prior studies have been shown to improve cardiac mechanic and/or metabolism. The purpose of these studies is to test a new compound, propionylcarnitine taurine (PCT), which potentially combines these actions, in a therapeutic trial to ...

Finding opiate receptors in the heart, definition of their role in contractility and blood flow regulation (2) as well as our previous data on the decrease of Leu-enkephalins contents in the blood of patients with myocardial infarction (5) are the theoretical prerequisites for the elucidation of the role of Leu-enkephalins ...

Overt cardiac failure usually presents with constant clinical features as consequences of the reduced pump action, associated with an increased adrenergic drive, independent of the underlying disease. However, the study of left ventricular function, before and during the phase of cardiac insufficiency, shows that different pathophysiological mechanisms are responsible for ...

Transient coronary occlusion (15 minutes) does not result in irreversible myocardial injury but is associated with a depression of contractile function sustained for several hours to days ("stunned myocardium"). The defect in the contractile process responsible for this phenomenon has been suggested to be causally related to a reduced energetic ...

The effect of halothane on myocardial contractility was studied in isolated right ventricular muscle preparations from newborn and adult rabbits. Right ventricular strips were mounted in oxygenated Krebs' solution and stimulated with supramaximal voltages at 1.0 Hz, while isometric force of contraction was continuously recorded. Halothane (0.4, 0.7, and 1.1%) ...

To elucidate possible mechanisms by which coenzyme Q10 enhances reoxygenation-induced recovery of cardiac contractile force after hypoxia, rabbit hearts were subjected to hypoxic perfusion for 20 min, followed by 45 min-reoxygenation with or without pretreatment with coenzyme Q10. Hypoxia induced a decline in cardiac contractile force, a decrease in myocardial ...

Ro 5-4864 (chlorodiazepam) increased coronary flow in isolated retrograde perfused Langendorff rat heart preparations without affecting heart rate and left ventricular contractility (dP/dt). On the other hand Ro 5-4023 (clonazepam) produced very little effect. PK 11195 which has been shown to inhibit the binding of Ro 5-4864 to cardiac muscle ...

The potential existence of a specific uremia-associated myocardial depressant factor was explored by evaluating nine pediatric subjects (3 to 21 years) without evidence of coronary artery disease or long-standing hypertension 1) before entering a dialysis program, 2) while undergoing a long-term dialysis regimen, and 3) after successful renal transplantation. Myocardial ...

Ultrasound examinations have been performed on 15 cosmonauts who have remained in orbit for flights ranging from 2.5 to 8 months in duration. Soviet researchers have combined hemodynamic assessments with parallel attempts to develop improved ultrasound techniques and equipment for use onboard space stations. These techniques and equipment are reviewed, ...

We have studied the action of nifedipine and nisoldipine on the contractile activity of human isolated coronary arteries and human isolated auricular and ventricular muscles. Nisoldipine depressed dose dependently the spontaneous rhythmic contractions displayed by the coronary artery preparations and at 1 nM abolished these contractions. Nisoldipine was twenty times ...

Despite the recent interest in contrast-enhanced echocardiography as a means of defining myocardial perfusion, the effects of echo contrast agents on left ventricular (LV) contractility in humans remains poorly defined. This is particularly relevant because intracoronary injection of contrast agents used for angiographic visualization of coronary arteries produces significant alterations ...

In the present paper, two experimental models of heart failure, namely hereditary cardiomyopathy in hamsters (BIO 14.6) and cardiac insufficiency due to mild (0.06 microM) isoprenaline overload of rabbit isolated perfused hearts, were compared in terms of resulting alterations at the level of the functionally isolated contractile system of detergent/glycerol ...

Some clinical studies that were performed for the purpose of assessing the potential cardiotoxicity of mitoxantrone (DHAD) have shown that repeated administrations of the drugs in some patients cause a mild impairment of cardiac functions and morphological changes in the myocardial cells qualitatively similar to those elicited by anthracyclines. Since ...

At present, the most widely used inhalational anaesthetics are the halogenated, inflammable vapours halothane, enflurane, isoflurane and the gas nitrous oxide. The anaesthetic effect of these agents is related to their tension or partial pressure in the brain, represented at equilibrium by the alveolar concentration. The minimum alveolar concentration for ...

We have evaluated the effects of nifedipine and verapamil on rate of left ventricular relaxation in 26 patients having coronary arterial disease with normal ejection fraction and normal left ventricular contractility. None of the patients had myocardial infarction. All patients showed normal contractile indices and abnormally high values of T ...

PN 200-110 (isradipine) is a new dihydropyridine calcium antagonist with selective actions on the heart as well as the peripheral circulation. It selectively inhibits the sinus node but not atrioventricular conduction and its negative inotropic action is minimal, about 20 times weaker than its negative chronotropic effect. This in vitro ...

The functional significance of alterations in contractile proteins was investigated in the chronically overloaded left ventricle of Goldblatt rats and spontaneously hypertensive rats (SHRs). Congestive cardiac insufficiency occurring in late stages of pressure overload is associated with impaired contractility, as well as significant structural dilatation. Only in the event of ...

The vascular versus myocardial selectivity of three structurally different calcium antagonists, felodipine, diltiazem, and verapamil, was studied in vitro. The model used was an isolated portal vein preparation and a paced (3 Hz) papillary muscle of the left ventricle of the rat, examined in the same organ bath. In previous ...

Using polycardiography, right and left ventricular dynamics were studied in 22 healthy women in the 30th--40th week of physiological pregnancy and 75 patients with different forms of late toxaemia. It was found that late toxaemia is accompanied by deep changes in the phase structure of the right ventricular systole, corresponding ...

Previous work from this laboratory has demonstrated that the colon, particularly the left colon, is the major site of persistent postoperative ileus after both minimal and more extensive abdominal operations. Inhalation anesthetics have been implicated in the past as a possible cause of altered postoperative bowel function, but direct evidence ...

The ability to induce alcoholic cardiomyopathy has been tested in a variety of animal species. Myocardial alterations consistent with subclinical heart disease have been produced in many of these studies through a direct effect of ethanol or its metabolites upon the heart or a neurohumoral mechanism. In the rat most ...

The mitochondrial activity as the energy producing step during biological oxidation was observed at rest and its regulation by the energy consuming auxotonic contractile work, depending on the preload, afterload and beat rate in isolated superfused left guinea pig atria. The mitochondrial activity was measured by (1) continuous determination of ...

The radionuclide right ventricular ejection fraction (RVEF) determined by means of Krypton-81m represents a simple, noninvasive, and accurate procedure to quantify the right ventricular contractility. This procedure was applied to 25 young patients with cystic fibrosis. The RVEF tended to decrease with the progression of the lung disease, as assessed ...

The authors studied total and segmental contractility of the left ventricular (LV) myocardium in patients with acute myocardial infarction with single and multiple coronary artery (CA) disease. The group included 75 patients with acute transmural myocardial infarction; coronary arteriography was performed in 56 of them. All patients underwent echocardiography (sector ...

Systemic vascular resistance (SVR) is a frequently used clinical index of left ventricular afterload. However, SVR may not adequately assess left ventricular afterload (i.e., ventricular internal fiber load during systole) since it reflects only peripheral vasomotor tone. In contrast, left ventricular end-systolic wall stress (sigma es) reflects the combined effects ...

Cardiac myolysis was observed in guinea pigs sensitized with vesicular stomatitis virus (VSV), following challenge with this antigen. The phenomenon developed within 1 h of challenge, appearing as islands in the myocardium. The speed and focal nature of the damage point to obstruction of blood flow as a cause of ...

The cardiotoxic potential of the phenothiazine neuroleptic thioridazine and five of its metabolites, including two stereoisomeric forms of thioridazine 5-sulfoxide (ring sulfoxide), was characterized in the isolated perfused rat heart. Hearts from male Sprague-Dawley rats were perfused using a modified Langendorff technique. After a 30-min control period, hearts were perfused ...

Myocardial intracellular pH was measured in a perfused rainbow trout, Salmo gairdneri, with DMO (5,5-dimethyl-2,4-oxazlidinedione), to test the hypothesis that catecholamines promote active regulation of myocardial pH in order to protect contractility during a respiratory acidosis comparable to that observed after exercise. Under control conditions (extracellular pH = 8.0; PCO2 ...

To determine the factors conditioning the variability of positive inotropic response after intravenous acute amrinone administration, 14 patients with chronic cardiac failure were studied by quantitative M-mode and cross-sectional echocardiography. Six patients had idiopathic dilated cardiomyopathy and 8 patients had severe chronic aortic insufficiency. Myocardial contractility (evaluated as peak arterial ...

This study was carried out to investigate the possible contribution of endogenous prostaglandin (PG) production to failure of contractile recovery following reperfusion of hypoperfused isolated rat hearts. A 90% reduction in coronary flow rate for 60 min resulted in a time-dependent depression of contractile force and an elevation in resting ...

The purpose of this study was to characterize by pharmacological means the inotropic action of prostaglandin D2 (PGD2) in the guinea-pig heart. In the whole heart perfused at constant pressure, PGD2 (0.01-10 micrograms) reduced coronary flow rate and decreased left ventricular contractile force in a dose-dependent manner. When the coronary ...

Adequate cardiovascular function depends on the control of venous tone as well as cardiac contractility, heart rate, vascular resistances, and an adequate blood volume. Venous tone is a major determinant of cardiac preload, a clinically important factor influencing cardiac function, especially during cardiac failure. In this review, vascular capacitance, venous ...

Hyperthyroidism has been reported to affect all of the major determinants of left ventricular performance in a manner that would augment ventricular shortening characteristics. The hypothesis tested in this study is that reduced afterload in conjunction with increased preload and heart rate, rather than augmented contractility, accounts for much of ...

Defibrotide, a simple strand polydeoxyribonucleotide of mammalian origin with a molecular weight of 20,000 daltons, given intravenously to the rabbit before and after production of left ventricular infarction, prevents the alteration of the contractile response to postsynaptic adrenergic stimulation tested in isolated perfused heart preparations 3 days after coronary artery ...