Enhancement of the effectiveness of milrinone to increase force of contraction by stimulation of cardiac beta-adrenoceptors in the failing human heart

1988 ◽  
Vol 66 (19) ◽  
pp. 957-962 ◽  
Author(s):  
M. Böhm ◽  
F. Diet ◽  
B. Kemkes ◽  
E. Erdmann
Keyword(s):  
Human Heart ◽  
Force Of Contraction ◽  
Beta Adrenoceptors ◽  
Stimulation Of

Entrainment and Annihilation of Reentrant Excitation in a Periodically Stimulated Ring of Excitable Media

1997 ◽  
Vol 36 (04/05) ◽  
pp. 290-293
Author(s):  
L. Glass ◽  
T. Nomura
Keyword(s):  
Cardiac Arrhythmias ◽  
Initial Phase ◽  
Human Heart ◽  
Periodic Wave ◽  
Excitable Media ◽  
One Dimensional ◽  
Clinical Observations ◽  
Periodic Stimulation ◽  
Reentrant Excitation ◽  
Stimulation Of

Abstract:Excitable media, such as nerve, heart and the Belousov-Zhabo- tinsky reaction, exhibit a large excursion from equilibrium in response to a small but finite perturbation. Assuming a one-dimensional ring geometry of sufficient length, excitable media support a periodic wave of circulation. As in the periodic stimulation of oscillations in ordinary differential equations, the effects of periodic stimuli of the periodically circulating wave can be described by a one-dimensional Poincaré map. Depending on the period and intensity of the stimulus as well as its initial phase, either entrainment or termination of the original circulating wave is observed. These phenomena are directly related to clinical observations concerning periodic stimulation of a class of cardiac arrhythmias caused by reentrant wave propagation in the human heart.

scholarly journals STUDIES WITH THE ELECTROCARDIOGRAPH ON THE ACTION OF THE VAGUS NERVE ON THE HUMAN HEART

1911 ◽  
Vol 14 (3) ◽  
pp. 217-234 ◽  
Author(s):  
G. Canby Robinson ◽  
George Draper
Keyword(s):  
Vagus Nerve ◽  
Mechanical Stimulation ◽  
Human Heart ◽  
Appreciable Effect ◽  
Vagus Stimulation ◽  
Ventricular Systole ◽  
Constant Change ◽  
The Right ◽  
Stimulation Of

In hearts showing auricular fibrillation mechanical stimulation of the right vagus nerve causes, as a rule, marked slowing or stoppage of ventricular rhythm, without producing any appreciable effect in the electrocardiographic record of the auricular fibrillation. The ventricular pauses are apparently due to the blocking of stimuli from the auricles. The force of ventricular systole is distinctly weakened for several beats after vagus stimulation, and ectopic ventricular systoles have been seen in several instances, apparently the result of the vagus action. There may, in some cases, be lowered excitability of the ventricles, while no constant change is seen in the size of the electrical complexes representing ventricular systole.

Malonate and fluoride effects on metabolism and contraction of electrically stimulated heart strips

1961 ◽  
Vol 200 (4) ◽  
pp. 727-731 ◽  
Author(s):  
Leslie I. Rice ◽  
David A. Berman
Keyword(s):  
Oxygen Consumption ◽  
Glucose Metabolism ◽  
Rat Heart ◽  
Contractile Activity ◽  
Simultaneous Recording ◽  
Force Of Contraction ◽  
Enzyme Systems ◽  
Pyruvate Oxidation ◽  
Oxidation Of Glucose ◽  
Stimulation Of

The effect of malonate and fluoride on the oxidation of C14-labeled substrates by electrically stimulated rat heart strips was investigated in an apparatus which permitted simultaneous recording of oxygen consumption and contractile activity. Malonate stimulated the force of contraction when glucose was the substrate, but not in the presence of pyruvate. Malonate had no significant effect on the rate of oxidation of glucose-1-C14, glucose-6-C14 or pyruvate-2-C14, indicating that its effect on contraction was not related to a) stimulation of glucose metabolism, b) inhibition of the Kreb's cycle, or c) stimulation of the phosphogluconate pathway. Malonate-2-C14 was oxidized by the ventricle strips, and the possibility exists that utilization of malonate as a substrate may account, at least in part, for its stimulation of contraction. The stimulation of contraction by fluoride was accompanied by significant alterations in metabolism. The oxidation of glucose and acetate was inhibited, whereas pyruvate oxidation was stimulated; these findings were interpreted in terms of known actions of fluoride on enzyme systems.

Further characterization of the receptors involved in the positive inotropic effect of histamine on rabbit papillary muscle

1986 ◽  
Vol 64 (12) ◽  
pp. 1484-1488 ◽  
Author(s):  
Alejandro Elizalde ◽  
Jesús Perez-Chavez ◽  
José Sánchez-Chapula
Keyword(s):  
Action Potentials ◽  
Positive Inotropic Effect ◽  
Phosphodiesterase Inhibitor ◽  
Adenosine Monophosphate ◽  
Inotropic Effect ◽  
Slow Inward Current ◽  
Force Of Contraction ◽  
Inotropic Effects ◽  
Slow Action Potentials ◽  
Stimulation Of

The effects of histamine on the force of contraction and calcium-dependent action potentials were studied in rabbit ventricular papillary muscles. The positive inotropic effect of histamine seems to be dependent on stimulation of H1 and H2 receptors. The H1 antagonist chlorpheniramine produced a competitive blockade of the positive inotropic effects of histamine. Cimetidine produced a competitive blockade, which was apparent only after blockade of H1 receptors. Histamine increased the maximum upstroke velocity of slow action potentials. This effect can be entirely accounted for by stimulation of H2 receptors. The phosphodiesterase inhibitor 3-isobutyl-methyl-xanthine potentiated the H2 receptor mediated effects of histamine on the force of contraction and slow action potentials. We conclude that rabbit ventricular muscle possesses both H1 and H2 receptors that mediate the positive inotropic effect of histamine. The H2-mediated effect seems to be causally related to an increase in the calcium slow inward current and is probably linked to an enhanced cellular cyclic adenosine monophosphate content. The mechanism of the H1-mediated positive inotropic effect remains unknown.

Halothane Restores the Altered Force-Frequency Relationship in Failing Human Myocardium

1995 ◽  
Vol 82 (6) ◽  
pp. 1456-1462. ◽  
Author(s):  
Ulrich Schmidt ◽  
Robert H. G. Schwinger ◽  
Michael Bohm
Keyword(s):  
Cardiac Surgery ◽  
Human Heart ◽  
Positive Inotropic Effect ◽  
Negative Inotropic Effect ◽  
Human Myocardium ◽  
Inotropic Effect ◽  
Force Frequency ◽  
Beta Adrenoceptors ◽  
Frequency Relationship

Background The terminally failing human myocardium exerts a negative force-frequency relationship (FFR), whereas a positive FFR occurs in nonfailing myocardium. To study the possibility of pharmacologically influencing this defect of the failing human heart, the effect of halothane on the basal FFR and the FFR in the presence of isoproterenol and ouabain was investigated. Methods Experiments were performed on isolated, electrically driven (0.5-2 Hz, 37 degrees C, Ca2+ 1.8 mmol/l) ventricular preparations. Myocardium from human failing and nonfailing hearts was obtained at cardiac surgery. To further characterize the studied myocardium, the positive inotropic effect of isoproterenol and the density of beta-adrenoceptors were measured using the radioligand 125I-CYP. Results Halothane produced a negative inotropic effect. The anesthetic (0.38 mmol/l) reversed the negative FFR in failing myocardium, antagonized the effect of isoproterenol (0.1 mumol/l) on FFR, and restored the FFR in the presence of ouabain. Conclusions Halothane restores the FFR in human failing myocardium possibly by influencing the intracellular Ca2+ homeostasis. These findings provide evidence that pharmacologic interventions, e.g., during anesthesia, may influence contractility also as a result of a depressed or enhanced FFR.

Nonlinear dynamics, chaos and complex cardiac arrhythmias

1987 ◽  
Vol 413 (1844) ◽  
pp. 9-26 ◽  
Keyword(s):  
Cardiac Arrhythmias ◽  
Human Heart ◽  
Complex Dynamics ◽  
One Dimensional ◽  
Clinical Observations ◽  
Stimulation Parameters ◽  
Finite Difference Equations ◽  
Periodic Stimulation ◽  
Stimulation Of

Periodic stimulation of a nonlinear cardiac oscillator in vitro gives rise to complex dynamics that is well described by one-dimensional finite difference equations. As stimulation parameters are varied, a large number of different phase locked and chaotic rhythms is observed. Similar rhythms can be observed in the intact human heart when there is interaction between two pacemaker sites. Simplified models are analysed, which show some correspondence to clinical observations.

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