Methionine enkephalin as a possible neuromodulator of regional cerebral blood flow

Summary In swine, cerebral blood flow was documented by a left ventricular injection of radiolabeled 15-micron spheres. Utilizing this procedure, the effect of the putative neurotransmitter methionine-enkephalin on regional cerebral blood flow was systemically evaluated. Our results revealed that a peripheral infusion of methionine enkephalin into miniature swine significantly increased cerebral blood flow in the basal ganglia, cerebellum, pons, inferior parietal cortex, superior parietal cortex and frontal cortex. Non-significant increases were observed in the hippocampus, occipital cortex and medulla oblongata while no effect on blood flow was observed in the pituitary gland. Significance of these results reside in the potential role of methionine enkephalin as a modulator of blood flow to the brain.     

Influence of diazoxide on regional blood flow in rats

Zusammenfassung Der Einfluss von Diazoxid auf die Organdurchblutung der Ratten wurde mittels⁸⁶Rb untersucht. Eine signifikante Durchblutungssteigerung des Herzens (128% der Kontrollwerte) und der Schilddrüse (139%) konnte bis 150 sec nach i.v. Injektion von 5 mg Diazoxid nachgewiesen werden. Die Durchblutung der Milz hingegen sank rasch auf 45% der Kontrollwerte, wobei nach 150 sec Normalisierung eintrat.     

Methionine enkephalin inhibits the bursting activity of the Br-type neuron inHelix pomatia L.

Summary The present study demonstrates that methionine enkephalin can inhibit the normal bursting activity pattern of the RPal or Br-type neuron and this inhibition can be blocked by prior treatment with naloxone, the selective opiate antagonist. The study demonstrates indirectly the presence of opiate-like receptors inHelix pomatia.Acknowledgments. This work was funded by grant RR 08171 Division of Research Resources and NIMH, and a National Academy of Sciences Travel grant and a Hungarian Academy of Sciences research support award to G.B.S. We also gratefully acknowledge thoughtful comments from Dr J. Salanki.     

Methionine enkephalin inhibits the bursting activity of the Br-type neuron in Helix pomatia L

The present study demonstrates that methionine enkephalin can inhibit the normal bursting activity pattern of the RPal or Br-type neuron and this inhibition can be blocked by prior treatment with naloxone, the selective opiate antagonist. The study demonstrates indirectly the presence of opiate-like receptors in Helix pomatia.     

Cardiac output and regional blood flow studies in golden hamsters

Summary A method is described for the acute catheterization of the left ventricle of the heart and descending aorta combined with the use of the radioactive microsphere technique to study hemodynamic parameters in anaesthetized hamsters. The hemodynamic parameters studied include mean blood pressure, cardiac output, percentage distribution of cardiac output and regional blood flows in different organs.     

Dopamine and cerebral cortical blood flow in the rat

Summary Dopamine topically applied to the cerebral cortex (1–20 g/ml) or administered i.v. (0.5–64 g/kg/min) has no effects on cerebral cortical blood flow in the rat.     

The blood flow of the cerebral cortex determined by radioactive krypton85

Zusammenfassung Der radioaktive indifferente Luftbestandteil Krypton⁸⁵ (in Ringer-Flüssigkeit) wird in die Arteria carotis communis injiziert und die Radioaktivität über der freigelegten Gehirnoberfläche verfolgt. Die Methode ergibt reproduzierbare quantitativecorticale Perfusionswerte und eignet sich auch für andere Gewebe.     

The effect of polysaccharide-protein complex isolated fromCandida albicans on regional blood flow in rats

Summary After i.v. administration to rats of polysaccharide-protein complex, isolated fromCandida albicans, a decrease of cardiac output was observed from 20 sec to 240 min postinjection, followed by a recovery at 360 min. Concomitantly the regional blood flow was maintained in heart and lungs, moderately decreased in intestine, liver and adrenals and markedly reduced in skin, muscle, spleen and kidney.     

The effect of LSD-25 upon the cerebral blood flow and EEG in cats

Zusammenfassung Es wurde gezeigt, dass LSD-25 (d-Lysergsäure-diäthylamid) in Dosen von 30 bis 100 /kg Körpergewicht bei dernichtnarkotisierten Katze (encéphaleisolé) meistens cine Erhöhung des zerebralen Gefässwiderstandes herbeiführte. In die Carotis injiziert, gab LSD-25 in denselben Dosen nach vorübergehender, halbseitiger Aktivierung eine Depression des Elektroenzephalogrammes. Kleinere Dosen gaben im EEG eine Aktivierung oder waren ohne Wirkung.     

The effect of polysaccharide-protein complex isolated from Candida albicans on regional blood flow in rats.

After i.v. administration to rats of polysaccharide-protein complex, isolated from Candida albicans, a decrease of cardiac output was observed from 20 sec to 240 min postinjection, followed by a recovery at 360 min. Concomitantly the regional blood flow was maintained in heart and lungs, moderately decreased in intestine, liver and adrenals and markedly reduced in skin, muscle, spleen and kidney.     

Proposed effects of brain noradrenaline on neuronal activity and cerebral blood flow during REM sleep

Summary We propose that the observed increases of both neuronal activity and cerebral blood flow seen throughout the brain during REM sleep may be effects of decreased central noradrenaline release.     

Relationships between cerebral transit time of non-diffusible indicators and cerebral blood flow. A comparative study with krypton85 and radioalbumin

Riassunto Il flusso sanguigno cerebrale è stato misurato con il metodo della clearance regionale del Kr⁸⁵. I valori del flusso sono stati confrontati con le misure del tempo medio di transito di radioalbumina nella stessa regione cerebrale. È stata dimostrata una correlazione significativa tra le due serie di misure, e sono stati calcolati i limiti fiduciali e di tolleranza per la regressione.

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This work has been supported by a Research Grant of the Consiglio Nazionale delle Ricerche.     

Effect of arterial oxygen tension on cerebral blood flow at different levels of arterial PCO2

Zusammenfassung Die Wirkung des arteriellen O₂-Partialdruckes auf die Durchblutung des Grosshirns, Kleinhirns und Hirnstammes bei normalen und erhöhten CO₂-Partialdrucken im arteriellen Blut wird an der anaesthesierten Katze untersucht. Die Wirkung des PaO₂ ist von der Höhe des PaCO₂ abhängig.     

Proposed effects of brain noradrenaline on neuronal activity and cerebral blood flow during REM sleep.

We propose that the observed increases of both neuronal activity and cerebral blood flow seen throughout the brain during REM sleep may be effects of decreased central noradrenaline release.     

Humoral autoregulation of blood flow and blood pressure

Zusammenfassung Vasoaktive Substanzen im arteriellen Blut können charakteristische Reaktionen des lokalen Strömungswiderstandes hervorrufen. Die einfachsten Beispiele dieser humoralen Autoregulation können durch intraarterielle Infusion von Acetylcholin (Autoregulation der Strömung) oder Noradrenalin (Autoregulation des Drucks) demonstriert werden. Es wird angenommen, dass der humoralen Autoregulation Bedeutung bei der normalen und pathologischen Kreislaufregulation zukommt.

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Supported by NIH grant No. HE 11747.

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The experiments were performed in the Division of Biomedical Engineering, University of Virginia, Charlottesville, USA.