Search results for "Inotrope"

The ineffectiveness of the NO-cyclic GMP signaling pathway in the atrial myocardium

1995

1. This study was performed to determine whether nitric oxide (NO) has direct effects on force of contraction (Fc) in atrial myocardium from rats, rabbits, guinea-pigs, frogs, and man. 2. Glyceryl trinitrate, isosorbide dinitrate, 3-morpholino-sydnonimine hydrochloride (SIN-1), and S-nitroso-N-acetylpenicillamine (SNAP) did not significantly reduce Fc in the various preparations investigated, either given alone or after stimulation of alpha- or beta-adrenoceptors. 3. SNAP did not change the time course of contractions in rat, guinea-pig and human preparations. 4. 8-Bromo-guanosine-3':5'-cyclic monophosphate (8-Br-cyclic GMP) produced a negative inotropic effect in rat, guinea-pig and human …

RELATIONSHIP BETWEEN THEOPHYLLINE UPTAKE AND INOTROPIC EFFECT IN THE GUINEA-PIG HEART

1974

1 The time course of the positive inotropic effect of theophylline was compared with the time course of the uptake and release of [(3)H]-theophylline in guinea-pig isolated, electrically driven hearts perfused by the Langendorff method.2 Formation of theophylline metabolites could not be detected under the experimental conditions used.3 Theophylline entered myocardial tissue very rapidly in two different phases. The first process (half-time 21 s) amounted to 93% and the second (half-time 5 min 50 s) to 7% of the total uptake. The development of the positive inotropic effect of theophylline was about four times faster than even the rapid component of the uptake of the drug into the myocardiu…

4-Aminopyridine antagonizes the inhibitory effect of pentobarbital on acetylcholine release in the heart

1980

Effects of pentobarbital on acetylcholine (ACh) release, force of contraction and nervous conduction were studied in isolated heart preparations and in cervical vagus nerves, respectively. 4-Aminopyridine and tetracaine were used as pharmacological tools to eludicate the mode of action of pentobarbital. 1. 4-Aminopyridine (10−4 M) markedly increased the overflow of ACh from the isolated chicken heart evoked by electrical stimulation (1–50 Hz, 1 ms, 40 V) of the cervical vagus nerves. This effect of 4-aminopyridine was highest at low frequencies of stimulation (+ 226% at 1 Hz) and declined with increasing frequencies to reach a minimum augmentation of 22% at 30 Hz. 2. Pentobarbital and tetra…

EFFECTS OF D-600 AND ITS OPTICAL ISOMERS ON FORCE OF CONTRACTION IN CAT PAPILLARY MUSCLES AND GUINEA-PIG AURICLES

1977

Abstract 1 (--)-D-600 and (+)-D-600 exerted concentration-dependent negative inotropic effects in papillary muscles from cats, the potency of (--)-D-600 being about 100 times greater than that of (+)-D-600. The action was more pronounced at high than at low frequencies of stimulation. Time to peak force, relaxation time and therefore also total duration of contraction were not significantly affected by the drugs. 2 The negative inotropic effects of both drugs were not reversible after washing in drug-free solution for 60 min at all concentrations tested. 3 The same negative inotropic effects were seen in guinea-pig left auricles with the racemic mixture of both isomers. 4 Uptake measurement…

Using FFR to Detect Ischemia in Myocardial Bridge Lesions

2016

Beyond atherosclerosis, a number of other phenomena may result in cardiac ischemia. Among these, extracoronary compression due to myocardial bridges may cause a dynamic stenosis and typical angina. The assessment of the hemodynamic relevance and the treatment of such lesions have unique characteristics that are due to the fact that extracoronary compression from myocardial bridges is mostly a systolic phenomenon and is dependent on the inotropic state. The consequence is that other hyperemic stimuli, such as dobutamine, may be more adequate to unveil ischemia in these settings.

Die positiv inotrope Wirkung von Theophyllin, Adrenalin und Strophanthin am Papillarmuskel bei Sch�digung durch Dinitrophenol, Azid, Chinin und Barbi…

1960

Über «therapeutische» und «toxische» Digitoxigeninwirkungen auf elektrophysiologische Messgrössen des Meerschweinchenvorhofs

1963

‘Therapeutic’ concentrations of digitoxigenin (10−7−3× 10−7 g/ml), producing positive inotropic effects, did not alter resting and action potentials of electrically driven guinea-pig auricles. However, ‘toxic’ concentrations of digitoxigenin (5 × 10−7−10−8 g/ml), producing arrhythmias and contracture of the myocardium, had a marked influence upon resting and action potentials and conduction velocity.

�ber den Einflu� von Mangan-Ionen auf die positiv inotrope Wirkung von Adrenalin, Theophyllin und Digitoxigenin an isolierten Meerschweinchenvorh�fen

1969

The influence of bivalent manganese ions (Mn++) on the positive inotropic effect of adrenaline, theophylline, and digitoxigenin was studied in isolated, electrically driven left guinea-pig auricles in phosphate-free Tyrode's solutions with different extracellular calcium concentrations ([Ca]e; 0.45; 1.8; 7.2 mM).

Über die Abhängigkeit der Acetylcholinwirkung von der äusseren Ca-Konzentration bei isolierten Meerschweinchenvorhöfen

1966

In the left auricles of guinea-pigs, Ca-ions have an antagonistic effect on the negative inotropic action of ACh. This effect is independent of the degree of shortening of the action potential by ACh.

Die Wirkung von Theophyllin, Coffein und Theobromin auf Kontraktionskraft, Erregbarkeit, Refrakt�rzeit und Spontanfrequenz des isolierten Herzmuskels…

1956

In the electrically driven papillary muscle of the cat's right ventricle theophylline, caffeine and theobromine exerted a positive inotropic action. Log. dose-effect regression lines for the three drugs were parallel; the effect of theophylline was significantly greater than those of caffeine and theobromine. The range of concentrations used was 1/32–1/2 mM/1.