Chronotropic changes due to pericardial distension in isolated frog hearts perfused in situ

Résumé On a démontré que la distension péricardiale produit des changements chronotropiques dans le cur de grenouille isolé en perfusion. Sur 26 curs, l'accélération cardiaque (18 a 148%) se produit dans 12 avec un volume de fluide péricardique atteignant 4 ml. Dans les 14 curs restant nous avons observé une bradycardie, des irrégularities de conduction, un blocage cardiaque et une arythmie. On en conclut que ces effects chronotropiques et les variations du paramètre d'impulsion sont dues aux changements dans l'activité du «pacemaker».     

Formation of gigantic mitochondria in hypoxic isolated perfused rat hearts

Zusammenfassung Herzen gesunder, erwachsener Ratten wurden mit Krebs-Henseleit-Bikarbonatlösung durchströmt (95% O₂5% CO₂). Bei künstlich herbeigeführter Hypoxie (95% N₂5% CO₂) erschienen die Herzmitochondrien innerhalb von 7 min bedeutend vergrössert und zu 25% miteinander verschmolzen.     

Fructose-1,6-diphosphate reduces acute ECG changes due to doxorubicin in isolated rat heart

Doxorubicin (DXR) (0.17 x 10(-4) M) induces an acute cardiotoxicity in isolated rat heart; there is a progressive widening of the S alpha T segment, with a decrease in force derivatives and in the coronary flow. Concurrent perfusion with fructose-1,6-diphosphate (FDP) (10(-5)-10(-4) M) dose-dependently reduces the S alpha T enlargement but fails to affect the reduction in force derivatives and coronary flow. The target of cardiac protection by FDP might be the ionic mechanisms underlying the action potential configuration.     

The resistance of in situ perfused lymph trunks and lymph nodes to flow

Résumé Les ganglions lymphatiques perfusés sur place résistent à l'élévation du débit lymphatique; cette résistance peut favoriser le dévéloppement de l'dème local.     

Facilitation of synaptic transmission by diazepam in a perfused frog cerebellum

Summary The action of diazepam on the parallel fibres-Purkinje cell synapse was studied in a perfused frog cerebellum. Diazepam facilitates the excitatory input to Purkinje cells and hence increases the inhibition produced by Purkinje cells activity.Supported by a grant from the Israel Center of Psychobiology.This work is part of M. D. Thesis by Y. B. N.     

RNA polymerase activities in the isolated perfused rat liver

Summary The routine procedure for the isolation of rat liver induces a significant fall in RNA polymerase I and II activities which are rapidly restored to the control levels during perfusion.     

Influence of nocloprost on the vascular responses to various stimuli in the isolated perfused rabbit kidney

Nocloprost, a new synthetic prostanoid, elicited a vasodilator action when given through the renal artery of the isolated perfused rabbit kidney. Lower concentrations of the compound inhibited the pressor response to sympathetic stimulation or to angiotensin II, but potentiated the pressor effect of exogenous noradrenaline. These results were taken as an evidence that nocloprost prevents the release of neurotransmitter by a presynaptic mechanism.     

Influence of nocloprost on the vascular responses to various stimuli in the isolated perfused rabbit kidney

Summary Nocloprost, a new synthetic prostanoid, elicited a vasodilator action when given through the renal artery of the isolated perfused rabbit kidney. Lower concentrations of the compound inhibited the pressor response to sympathetic stimulation or to angiotensin II, but potentiated the pressor effect of exogenous noradrenaline. These results were taken as an evidence that nocloprost prevents the release of neurotransmitter by a presynaptic mechanism.This work was supported by a grant from the Turkish Scientific and Technical Research Council (TAG-578). Nocloprost is the gift of Dr E. Schillinger, Head of Biochemical Pharmacology, Schering AG Research Laboratories, Berlin, FRG.     

The oxidation-reduction state of pyridine nucleotide in isolated frog gastric mucosa

Zusammenfassung In Magenschleimhaut des Frosches wird das Nicotinamid-adenin-dinucleotid nur im oxydierten Zustand gefunden. Die Absonderung der Säure in der Schleimhaut scheint von der Konzentration des reduzierten Pyridinnucleotids abhängig zu sein.

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This work was supported by a grant from the Smith Kline and French Foundation.     

Chemically mediated cell-to-cell contractile activation in isolated frog atrial cardiac cells

Summary A dying single frog atrial cardiac cell liberates an unknown substance which diffuses away from the dying cell and activates contractile activity in other isolated intact single cardiac cells within the vicinity of the dying cell.This investigation was supported by US Public Health Service, National Institutes of Health Grant HL 18943 and a Kansas Heart Association Grant-In-Aid.We wish to thank Dr Alan Chapman of the Department of Anatomy for doing the scanning electron microscopy of the cardiac cells.     

The effects of salicylate and aspirin on the activity of phosphorylase a in perfused hearts of rats

Summary Sodium salicylate and aspirin are known to have a glycogenolytic effect as judged by either the glycogen level or lactate production in perfused hearts of rats. In this work it was possible to demonstrate that phosphorylase a level was increased in the hearts subjected to the action of these drugs.