The effects of chronic alcohol ingestion in mice on contractile properties of cardiac and skeletal muscle: a comparison with normal and dehydrated-malnourished controls.

In vitro isometric contractile tension was measured in heart and skeletal muscle in 3 groups of mice: 1. a control group, 2. a group maintained for 27 weeks on 20% alcohol, and 3. a group whose fluid intake was restricted to the extent equaling that which occurred in the alcohol treated animals. Results showed a reduction in cardiac twitch tension in both the alcohol and fluid restricted group, as compared to normal controls. We therefore consider that dehydration per se may play an important role in the etiology of alcoholic cardiomyopathy.     

Effect of growth hormone and thyroxine on the contractile properties of dystrophic muscle

Résumé Chez des souris ayant une dystrophie musculaire, l'injection d'hormone d'accroissement et de thyroxine n'a pas d'effet. On l'a observé en mesurant la tension maximum de la secousse, le degré de reláchement et les courbes de fatigue dans des lambeaux étroits du muscle abdominal excisé.     

Tritiated water (HTO) and inulin spaces in isolated skeletal and cardiac muscles: influence of contractile activity

Summary In isolated cardiac and skeletal muscle inulin space increased significantly after isometric contractions: no significant change (in myocardium) or a less pronounced increase (in skeletal preparations) was found following isotonic responses. The HTO space was uninfluenced by the contractile activity.This work war partially supported by C.N.R., Italy, through grant No. 74.00266.     

Effect of histamine on the diameter of skeletal muscle fibers in mice

Résumé Des souris reçurent des injections intrapéritonéales de bichlorure d'histamine. Le diamètre moyen des fibres musculaires s'en trouva nettement réduit et des modifications histologiques furent notées chez les souris traitées.

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Supported by grant HD-00221, National Institutes of Health, U.S. Public Health Service. I wish to gratefully acknowledge the technical assistance of MissF. Vaughan.     

The phosphorylases system of the cardiac muscle of normal and reserpinized rats poisoned with 2,4-dinitrophenol

Résumé L'effet du DNP dans la glycogénolyse du cur du rat a été étudié en mesurant le taux de phosphorilasea, phosphorilase totale et phosphorilaseb-quinase. On a obtenu des résultats semblables à ceux qui ont été observés pendant l'anoxie. L'occurrence possible de deux mêchanismes d'accélération de la glycogénolyse («push» et «pull»), dans les animaux emploisonés par le DNP, est discutée.

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Acknowledgment. The authors wish to express their gratitude to Mr.A. F. Leite, J. Guimarães Filho, MissZimar Faria andMiss Samira Abdouch for the efficient technical assistance.     

The effects of secretin on urinary volume and electrolytes in normal subjects and patients with chronic pancreatic disease

Zusammenfassung Injektion von Sekretin ruft bei normalen Versuchspersonen Diuresis und Vermehrung der Natrium- und Alkali-Ausscheidung hervor. Diese Wirkungen sind vermindert bei Patienten mit chronischer Pankreaserkrankung. Der mögliche Mechanismus und die praktische Bedeutung dieser Beobachtungen werden diskutiert.

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Supported successively by grants from the Royal Free Hospital Endowment Fund.     

The effects of acute and chronic morphine on regional distribution of cardiac output in brain

Both acute and chronic administration of morphine resulted in an increase in the percent cardiac output received by brain. However, various brain regions were affected differently by the drug treatments. The greatest increases in percent cardiac output received after chronic administration of morphine occurred in pons and cerebellum, while the greatest increases after acute administration occurred in cortex and midbrain. The changes found are in contrast with earlier studies which suggest that morphine has no effect on cerebral blood flow.     

The effects of acute and chronic morphine on regional distribution of cardiac output in brain

Summary Both acute and chronic administration of morphine resulted in an increase in the percent cardiac output received by brain. However, various brain regions were affected differently by the drug treatments. The greatest increases in percent cardiac output received after chronic administration of morphine occurred in pons and cerebellum, while the greatest increases after acute administration occurred in cortex and midbrain. The changes found are in contrast with earlier studies which suggest that morphine has no effect on cerebral blood flow.     

A comparison of ultrastructural localization of carnitine acetyltransferase activity in mouse liver mitochondria with that in cardiac muscle

Résumé En microscopie électronique l'etuee de la carnitine acétyltransférase a montré une même localisation dans les mitochondries du foie et du muscle cardiaque de souris. La grande différence d'activité que décèlent les méthodes biochimiques entre ces deux types de mitochondries peut donc être attribuée simplement à la présence 'und nombre beaucoup plus grand de crêtes dans les mitochondries du muscle cardiaque.

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Supported by grants from Medical Research Council of Canada and the Muscular Dystrophy Association of Canada.

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Dr.T. Makita is a recipient of post-doctoral fellowship from the Muscular Dystrophy Association of Canada.

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The authors wish to express their appreciation to Dr.P.-E. Messier, MissesAndrée Aubin, Cécile Venne, Heather Stephens and Mr.J.-P. Marcil for their assistance in preparation of this communication.     

The influence of the extracellular potassium concentration on the glycoside effects upon contractile force and action potential duration of the guinea-pig papillary muscle

Zusammenfassung Eine Verringerung der extrazellulären Kaliumkonzentration im Bereich zwischen 9,6 und 2,4 mM führt zu einer Zunahme der positiv inotropen Glykosidwirkung am Meerschweinchenpapillarmuskel; die Wirkung des Adrenalins wird nicht beeinflusst. Die Vergrösserung der inotropen Wirkung geht parallel einer starken Zunahme der Verkürzung der Aktionspotentialdauer, besonders in Höhe des Plateaus (30% Repolarisation).     

The effect of tetrodotoxin on the sypaptic and extrasynaptic membrane in frog skeletal muscle

Summary Tetrodotoxin resistant sodium channels have been shown to operate in frog muscle membrane, which are responsible for local action potentials. These channels are located mainly in synaptic regions, and their distribution on the membrane is controlled by neurotrophic factors.     

The effect of tetrodotoxin on the synaptic and extrasynaptic membrane in frog skeletal muscle

Tetrodotoxin resistant sodium channels have been shown to operate in frog muscle membrane, which are responsible for local action potentials. These channels are located mainly in synaptic regions, and their distribution on the membrane is controlled by neurotrophic factors.     

The electrophysiological effects of ionophore X-537A on cardiac Purkinje fibres

Summary Using classical microelectrode techniques in canine cardiac Purkinje fibres, calcium ionophore X-537A was shown to shorten the action potential, hyperpolarizing the membrane and lowering the plateau, suggesting that intracellular calcium controls membrane permeability to potassium in this preparation.This work was supported by grant No. HL 05726 from the U.S. Public Health Service, National Heart Institute, Bethesda, Md.I thank Dr.N. Krasnow for his valuable advice in carrying out this work.     

The potent tremorgenic neurotoxins lolitrem B and aflatrem: A comparison of the tremor response in mice

Summary Tremor dose-response curves were determined for mice dosed with the ryegrass neurotoxin lolitrem B, and the tremorgenic mycotoxin aflatrem. A family of characteristic curves was revealed for each tremorgen, with lolitrem B eliciting a sustained tremor response persisting for over 24 h.