Pharmacological studies on thiamine deficiency IV. Blood catecholamine content and blood pressure of thiamine deficient rats

Zusammenfassung Wegen der Senkung des Blut-Katecholamin-Spiegels in unter experimentell erzeugtem Thiaminmangel stehenden Ratten kommt es zu einer Hypotonie. Die Abschwächung der spontanen Freisetzung des Katecholamins aus dem katecholaminspeichernden Gewebe bei Thiaminmangelratten ist als ein Faktor bei der Aminakkumulation bei Thiaminmangel zu denken.     

The effects of intracerebrally injected oxythiamine on free thiamine and thiamine phosphates content of rat brain

Riassunto L'iniezione intracerebrale di 0,6 moli di OTh nel ratto causa duraturi sintomi di ipereccitabilità e, dopo 24 ore, una modesta diminuzione del contenuto cérébrale di Th fosforilata. L'iniezione di 0,15 moli causa soltanto una molto lieve diminuzione del contenuto che compare al quarto giorno dall'iniezione.     

Effect of prolonged hypokinesia on thiamine phosphoric esters content in rat myocardium

Summary Under the effect of prolonged immobilization, the content of thiaminemono-, thiaminedi- and thiaminetriphosphate in rat myocardium decreases.     

Effect of lipophilic cations on thiamine transport system in isolated rat hepatocytes

The effect of lipophilic cations such as triphenylmethylphosphonium, tetraphenylphosphonium and tetraphenylarsonium in addition to dibenzyldimethylammonium on thiamine transport in isolated rat hepatocytes was studied. Lipophilic cations at the concentration 10 microM almost completely inhibited thiamine uptake. Kinetic studies showed that these compounds were competitive inhibitors with a very high affinity. These results suggest that lipophilic cations in addition to quaternary ammonium compounds also share a common binding site for thiamine in isolated rat hepatocytes.     

Action potentials of the guinea pig heart in sodium deficient solutions

Zusammenfassung Es werden Aktionspotentiale vom Meerschweinchenvorhof in Badelösungen verschiedener Na-Konzentrationen mittels intrazellulärer Elektroden registriert. Während das Aktionspotential desVentrikels relativ unempfindlich gegen Veränderungen der Na-Konzentration bleibt^{4, 6}, lässt sich die «Na-Hypothese» für denVorhof anwenden.

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Aided by a grant from the Italian Consiglio Nazionale delle Ricerehe.     

Decrease of norepinephrine in brain and heart of vitamin E deficient rats

Zusammenfassung Viermonatiger Vitamin-E-Mangel bewirkt bei Ratten einen etwa 25 prozentigen Abfall des Noradrenalin-Gehaltes in Gehirn und Herz, der durchdl--Tokopherol rückgängig gemacht wird. Die Abnahme des Noradrenalins erfolgt ohne gleichzeitige Verminderung der Tyrosin-Hydroxylase- und Dopamin--Hydroxylase-Aktivität.     

An electron microscopic observation on diplococcus-shaped vesicles in papillary muscle of rat heart

Zusammenfassung Vesikelartige Gebilde wurden in Papillarmuskeln von Ratten beobachtet. Diese wie Diplokokken aussehenden Doppelvesikel lagen an der Zelloberfläche, innerhalb der transversalen Tubuli und im Zwischenraum der Glanzstreifen. Die Ergebnisse lassen eine enge Beziehung zwischen diesen diplokokkenartigen Vesikeln und den sogenannten Zystisomen vermuten.     

Intercellular pathways in the heart: Direct evidence for low resistance channels

Zusammenfassung In einzelne Zellen von Kaninchen-und Rattenherzen wurde Natriumfluoreszin injiziert, wobei der Farbstoff direkt von Zelle zu Zelle diffundierte, aber nicht merklich auf den Extrazellulärraum übertritt. Daraus wird gefolgert, dass zwischen den Myocardzellen Verbindungswege existieren, von wo aus Impulse weitergeleitet werden können.

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Supported by grants Nos. HL 13517, GM 15991 and GM 16436 from the National Institutes of Health.     

Morphological evidence for calcium storage in the chromatoid body of rat spermatids

Summary Morphological evidence for probable Ca²⁺ storage in the vesicular elements of the rat spermatid chromatoid body is documented using the K-pyroantimonate method, combined with EDTA chelation. Some vesicles are related to the microtubules associated with the chromatoid body. A possible involvement of Ca²⁺ in the intracellular movement and/or structural integrity of the chromatoid body is discussed.     

Morphological evidence for calcium storage in the chromatoid body of rat spermatids

Morphological evidence for probable Ca2+ storage in the vesicular elements of the rat spermatid chromatoid body is documented using the K-pyroantimonate method, combined with EDTA chelation. Some vesicles are related to the microtubules associated with the chromatoid body. A possible involvement of Ca2+ in the intracellular movement and/or structural integrity of the chromatoid body is discussed.     

Myocardial force production and energy turnover in anoxia

ATP turnover of isolated rabbit papillary muscles, contracting isometrically at 20 degrees C, was determined in oxygen and during 40 min of exposure to nitrogen (anoxia). Stimulus frequency was 0.2 hertz (Hz) in oxygen and 0.2 or 1.0 Hz in nitrogen. In oxygen, ATP turnover was determined from oxygen consumption using a P/O2 ratio of 6.3. The time-dependent rate of ATP turnover in nitrogen was found from the production of lactate, and the changes in adenine nucleotides and phosphocreatine, measured in rapidly frozen preparations at different time-points during the anoxic period. A P/lactate ratio of 1.5 was used. In muscles stimulated at 0.2 Hz, twitch force dropped during the anoxic period to 33% while force production of muscles stimulated at 1.0 Hz stopped completely. However, in the latter muscles, resting force rose to 19% of the twitch force in oxygen. The rate of ATP hydrolysis in anoxia depended strongly on stimulus frequency, indicating that it is not solely determined by the glycolytic capacity. In the 0.2 Hz-stimulated muscles the decrease in energy turnover occurred in parallel with the drop in force. However, the rise in resting force in muscles stimulated at 1.0 Hz occurred when ATP turnover was close to zero. It was concluded that anoxia hardly affects the energy required for twitch force production, but that the rise of resting force measured when twitch force had disappeared occurred when the rates of cross-bridge cycling and calcium turnover were very low.     

Histochemical evidence for a somatotopic organization of the rubrospinal projection in the rat

Résumé La technique de l'acétylthiocholine démontrant l'activité de l'acétylcholinesterase fût employée pour indiquer la perte régionale d'enzyme des cellules nerveuse du noyau rouge du rat à la suite d'une lésion du faisceau rubrospinal. Les lesions aux niveaux thoraciques inférieurs du cordon médullaire donnent lieu à une perte d'enzyme des cellules dans la partie ventrale de la moitié caudale du noyau rouge. Cependant, les lésions du faisceau aux niveaux cervicaux du cordon médullaire donne lieu à une perte d'enzyme de la partie ventrale ainsi que de la partie dorsale de la moitié caudale du noyau. On suggère que cela indique une organization somatotopique de la projection rubro-spinale chez le rat.

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Supported by a grant from the Canadian Medical Research Council.