Wiederherstellung des normalen Herzschlages nach elektrisch erzeugtem Kammerflimmern durch Adenosintriphosphorsäure

Summary (1) In the isolated mammalian heart (rabbit, cat, dog) electrically induced ventricular fibrillation is stopped in practically 100% of the cases by adenosin-triphosphoric acid (ATP) in doses of 0.25–20 mg, and the normal rhythm of the heart is permanently restored (as far as the experiment extends).(2) This effect of ATP follows from a primary blocking, which leads to a complete cessation of the activity of the ventricles with diastolic dilatation of the heart.(3) In as much as adenyl acid from yeast and adenosin (in large doses) also stop ventricular fibrillation, the energetic effect of ATP seems to be of no importance in stopping it; it is a specific effect of the adenyl compounds on the bundle ofHis.     

The mechanical and biochemical effects of pentoxifylline on the perfused rat heart

Perfusion of the isolated rat heart at constant heart rate and coronary flow with the inhibitor of cyclic nucleotide phosphodiesterase, pentoxifylline (10(-4) moles/l), produced no significant effect on the maximum rate and the peak of contraction, but increased the maximum rate of relaxation. cAMP level and cAMP-dependent protein kinase activity were increased in the absence of changes in cGMP. The results were identical in hearts of reserpinized rats.     

Über die Steuerung des Ionengleichgewichtes zwischen Zellen und umgebender Flüssigkeit beim isolierten Froschherzen

Summary (1) The isolated frog's heart, repeatedly washed with Ca-free Ringer's solution, stops and, after discontinuing washing, begins to move again in spite of Ca lack. The heart adapts in the same way to the common lack of Ca and K, furthermore to Ringer's solution containing 10–20 times more K than normal.(2) Adaptation was not observed on isolated ventricle driven with electrical current.(3) It is concluded that the isolated frog's heart adapts to the ion composition of the surrounding fluid as a whole, and that the auricle plays an essential role in this process.     

Effect of prostaglandin E2 (PgE2) on the biosynthesis and metabolism of noradrenaline (NA) in the isolated and perfused rabbit heart]

In isolated perfused rabbit heart, Pg E2 at concentrations ranging from 1.10(-8) to 1.10(-4) M has shown no significant action either on the biosynthesis or on the metabolism of NA. But it inhibited NA uptake, nevertheless this action was weak.     

Die Wirkung von Herzglykosiden und Kalzium auf den Kaliumtransport im Herzmuskel

Summary In isolated perfused guinea pig hearts, both strophanthin and calcium produced positive inotropic effects and contracture increasing with the concentration of the drugs. Strophanthin caused a net loss of potassium from the heart to the perfusing fluid whereas calcium did not interfer in the same way with potassium exchange. The data are consistent with the view that the positive inotropic effect of cardiac glycosides depends mainly on the increased intracellular calcium concentration, perhaps due to inhibition of the active potassium and sodium transport.     

Uptake of noradrenaline in high altitude native's heart

Summary Uptake of³H-noradrenaline by the heart was studied with sections of isolated atria obtained from high or lowlanders. In native highlanders, affinity for³H-noradrenaline by human atria is more significant than in lowlanders. Furthermore, the Michaelis Menten constant is lower in high altitude native's heart.     

Zur Pharmakologie von Psilocybin,einem Wirkstoff ausPsilocybe mexicana Heim

Summary The active principle ofPsilocybe mexicana Heim, Psilocybin, is without marked effects on the isolated organs (seminal vesicle, intestine and auricle of the guinea pig; rat uterus) but exerts an actionin vivo which resembles a slight sympathetic stimulation. In unanaesthetized rabbits it produces mydriasis, tachycardia, tachypnea, hyperthermia and hyperglycemia, in unanaesthetized mice mydriasis and piloerection. The EEG (curarized rabbits) after 1–2 mg/kg Psilocybin shows an alerting pattern (disappearance of spindle activity and of slow waves). Spinal reflexes of the cat are predominantly enhanced. However, the motor activity of mice, rabbits and monkeys is unaffected or even slightly depressed. In anaesthetized cats and dogs Psilocybin affects blood pressure and heart rate, the effect depending on dosage and species.     

Inhibitory effect of taurine on decrease in the inotropic action of ouabain at high concentrations in isolated atria

Summary In vitro, taurine was shown to inhibit the decrease in the inotropic effect of ouabain at large doses in the normal and also low K⁺ medium in which this decrease in the inotropism of ouabain was facilitated. This inhibitory effect of taurine was, at least in part, due to the inhibition of the efflux of intracellular K⁺ in the isolated heart.     

Bradykinin-induced stimulation of cardiac parasympathetic ganglia

Summary Bradykinin slows the heart rate of the rabbit isolated heart. It appears to act as a non-nicotine-like stimulant on the cardiac parasympathetic ganglia.We thank Miss L. Späth and Mr E. Schöffel for skilled technical assistance. This study was supported by the Deutsche Forschungsgemeinschaft.     

Quantitative changes in beta-adrenergic responses of isolated atria from hyper- and hypothyroid rats

Concentration-response curves for the chronotropic and inotropic effects of isoprenaline, in the absence and presence of propranolol, were obtained on heart atria isolated from normo- or dysthyroid rats. Hyperthyroidism increased the chronotropic potency and efficacy of the beta-adrenergic agonist. The results are compatible with the view that thyroid hormone increases the density of functional beta-adrenoceptors in cardiac pacemaker tissue.     

The mechanical and biochemical effects of pentoxifylline on the perfused rat heart

Summary Perfusion of the isolated rat heart at constant heart rate and coronary flow with the inhibitor of cyclic nucleotide phosphodiesterase, pentoxifylline (10^–4 moles/l), produced no significant effect on the maximum rate and the peak of contraction, but increased the maximum rate of relaxation. cAMP level and cAMP-dependent protein kinase activity were increased in the absence of changes in cGMP. The results were identical in hearts of reserpinized rats.This work was supported by grants from the Consejo Nacional de Investigaciones Cientificas y Técnicas and the Comisión de Investigaciones Científicas. Buenos Aires, Argentina.We thank Hoechst Laboratories for the partial support and Mrs Alicia R. Ramirez and María Prinzo for the excellent technical assistance.     

Quantification of melanin in hepatic and cardiac lipofuscin

Summary Melanin pigment in liver and heart tissue, obtained at autopsy from patients, was isolated and quantified. The quantity of melanin extracted was directly proportional to lipofuscin granule counts. Infrared and electron spin resonance spectrographs of the isolated pigments from liver and heart showed absorption characteristics identical to those of known melanins. The pigment was absent in fetal and neonatal life, increased in brown atrophy of the heart and liver, and diminished in livers with fatty metamorphosis.Supported by USPHS, grant NS 07542, the St. Vincent Hospital Research Foundation and the Dermatopathology Foundation.     

Failure of opioids to affect excitation and contraction in isolated ventricular heart muscle

The opioid agonists morphine (selective for mu-receptors) and ethylketocyclazocine (selective for kappa-receptors), at concentrations evoking strong effects in neuronal structures, did not significantly affect the configuration of the intracellularly recorded action potential and the force of contraction in ventricular heart muscle isolated from guinea pigs, rabbits and man. These results suggest that any changes of heart functions in vivo in response to opioid-like drugs are probably not mediated postsynaptically at the myocardial cell membrane but rather presynaptically, influencing the release of noradrenaline and/or acetylcholine from the nerve terminals.     

Effect of hypoxia on glycolysis in isolated fetal rat heart]

Glycolysis was assessed in the isolated foetal Rat in hypoxia. Measurements were made of glucose uptake, lactate output, C14 glucose incorporation into glycogen and tissular levels of ATP, PCr, glycogen and lactate. Glycolysis was stimulated by hypoxia to a greater extent in the young foetal heart of 16.5 days post coitum than in the foetal heart at term. Thus high energy phosphates were maintained at a higher level in the younger heart. The results are discussed in relation to the high resistance to hypoxia of the foetal heart.     

The influence of prostacyclin (PGI2) on contractile properties of isolated right ventricle of rat heart

The mechanism of the positive inotropic effect of prostacyclin (PGI₂) (2.6×10^?6 mol/l) on the isolated right ventricle of rat heart was studied. Our results show that the positive inotropic effect of prostacyclin is produced indirectly through beta adrenoceptors and slow Ca²⁺ channels, because blockade of slow Ca²⁺ channels with verapamil (10^?6 mol/l) and beta adrenoceptors with propranolol (10^?6 mol/l) abolishes this effect. Alpha adrenoceptors do not mediate the action of PGI₂.     

Dosis-Wirkungs-Beziehungen zwischen Koronardurchfluss und Herzfrequenz für Adenosin

Summary In the isolated guinea-pig heart, it has been found that the amount of adenosine which slows the heart rate is about 100 times greater than the amount which increases coronary flow.     

Über die Reaktion der höheren und tieferen Reizbildungszentren des isolierten Herzens auf Temperatursenkung

Summary In the isolated rabbit heart perfused by the Langendorff method total heart block has been produced by section of the His bundle. The influence of cooling of the perfusion fluid upon higher and lower automatic centers was studied. The sinoauricular pacemaker responded to cooling with a much greater decrease of the heart rate than did the ventricular automatism. The responsiveness of the atrioventricular node to cooling lay between that of the two others.     

Comparative oxidation of erucic and oleic acids by mitochondria isolated from heart auricle of living man]

Mitochondria were isolated from fragments of heart auricles, that were cut off during surgical intracardiac operations. They were incubated with either [14 14C] erucic acid or [10 14C] oleic acid as a control. In the experimental conditions used, the radioactive products soluble in perchloric acid, that are issued from the beta-oxidation reactions in mitochondria, were formed in much lower amounts from erucic acid than from oleic acid. These results show the very low capacity of human heart mitochondria to use directly erucic acid as a substrate for energy requirements, as has been observed before with other animal species. Activation of fatty acids, the preliminary step of their beta-oxidation, was also observed to be very much lower with erucic acid.     

Zur Kenntnis des Muscarins

Summary The alkaloid muscarin was isolated from fly agaric. The analyses of crystallized salts (chloride, tetra-chloroaurate,Reinecke's salt) led to C₉H₂₀O₂N⁺ as the simplest formula. The presence of aldehyde and tri-methyl-ammonium groups, which had been assumed hitherto, could not be proved. The quaternary nature of the nitrogen atom was shown. Pharmacological tests on frog heart, rabbit gut and cats show the purely peripheral parasympathomimetic effect of the smallest doses.     

Adenosine is a sensitive oxygen sensor in the heart

Cardiac adenosine is formed both by an oxygen-sensitive (AMP----adenosine) and by an oxygen-insensitive (S-adenosylhomocysteine----adenosine) pathway. The phasic adenosine release during beta-adrenergic stimulation with isoproterenol is closely linked to coronary venous PO2 (isolated heart) and can be almost fully prevented when diastolic aortic pressure is maintained constant (heart in situ). During pressure autoregulation the transmural gradient of free adenosine is only increased when the autoregulatory reserve is exhausted. The critical PO2 below which adenosine formation is enhanced was found to be 3 mm Hg (isolated cardiomyocytes). Collectively, these data indicate that the formation of adenosine is not primarily coupled to the energy expenditure of the heart but to the supply/demand ratio for oxygen.