Photodynamic effect of dye on frog muscle fibre using microelectrodes

Zusammenfassung Kurarisierte und nichtkurarisierte Frosch-Sartorii zeigten einen veränderlichen Grad der Depolarisation, wenn sie mit Bengalrot (1:25 000) gefärbt und durch scharf zentriertes Licht einer 300-Watt-Tungsten-Lampe beleuchtet wurden. Die Depolarisation wurde niemals im äusseren Natrium und ohne Sauerstoff beobachtet.     

Studies on muscle fibre splitting in skeletal muscle

Summary Autoradiographic, stereological and histological studies have been carried out to determine the origin of muscle fibre splitting which supposedly occurs during muscle hypertrophy. The results obtained clearly indicate that the supposedly split fibres are a transient response probably derived from satellite cells and are not derived from pre-existing fibres by true splitting. Similarly, increases in muscle fibre size are not achieved by recruitment of satellite structures as indicated by lack of myonuclear recruitment.Acknowledgment. This work was carried out with the aid of a grant from the Medical Research Council of Great Britain. The authors are grateful for the excellent technical assistance of Miss H. Caulton, M.J. Wild and M. Fenner.     

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 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 intracellular potassium ions on active sodium efflux in frog sartorius muscle

Zusammenfassung Radioaktive Untersuchungen zeigen. dass intrazelluläre K⁺-Ionen den aktiven Na⁺-Austausch hemmen.     

Contraction of frog stomach muscle and frog heart in electrolyte-free solutions

Zusammenfassung Der Verlust der Reizbarkeit bei Froschherz- und Magenmuskulatur auf verschiedenen Temperaturstufen verläuft parallel mit einem Adenosintriphosphat-Verlust, was andeutet, dass das Nichtfunktionieren in natriumfreier Lösung von einem Adenosintriphosphat-Verlust abhängig ist.     

Sexual dimorphism in contraction properties and fibre of the flexor carpi radialis muscle of the frog (Rana temporaria L.)

Zusammenfassung Es wird ein Sexualdimorphismus beim Daumenbeugemuskel (m. flexor carpi radialis) des Frosches (Rana temporaria L.) mit Bezug auf das Kontraktionsverhalten, wie auch in histochemischer Richtung, festgestellt. Kontraktions- und Relaxationszeit sind bei männlichen Muskeln veralaugsamt mit entsprechender ATPase-Aktivität. Saionbedingte, geschlechtstypische Testosteronkonzentrationen stehen damit im Zusammenhang.     

Some ultrastructural observations on the denervated skeletal muscle of frog

Summary The frog skeletal muscle resists atrophy for a long time after denervation. If, however, the entry of the nerve is prevented for more than 3.5 months, small muscle portions, sometimes containing nucleus, are sequestered from the parent muscle fibre. The basal lamina does not dissociate from these detached muscle portions.     

Some ultrastructural observations on the denervated skeletal muscle of frog.

The frog skeletal muscle resists atrophy for a long time after denervation. If, however, the entry of the nerve is prevented for more than 3.5 months, small muscle portions, sometimes containing nucleus, are sequestered from the parent muscle fibre. The basal lamina does not dissociate from these detached muscle portions.     

Hypophysectomy exerts a radioprotective effect on frog lens

Summary Exposure to X-rays usually causes cataracts in frogs. These cataracts are always preceded by misalignment of the structures called meridional rows (MR). When cell division is completely halted by hypophysectomy, however, irradiation no longer disturbs the orientation of the MR. Since the MR are the structures formed as lens epithelial cells differentiate into lens fibres it is reasonable to propose that radiocataractogenesis depends upon a mitosis-driven formation of pathological fibres from epithelial cells that have been rendered abnormal by exposure to X-rays.This research was supported by: NIH grant No. EY 02492-02 (HR); NIH grant No. EY 02648-02 (BVW).     

Colchicine inhibition of ADH effect on frog skin permeability

Summary ADH and AMPc enhance both thiourea unidirectional fluxes in frog skin. This effect is completely abolished by colchicine pretreatment. The ADH increase of thiourea discharge with or without colchicine led us to suppose that colchicine does not directly affect ADH action on outer membrane permeability, but exerts its effects on a site which is limiting for the ADH action on transepithelial permeability.The present work has been supported by C.N.R., Rome.     

Colchicine inhibition of ADH effect on frog skin permeability

ADH and AMPc enhance both thiourea unidirectional fluxes in frog skin. This effect is completely abolished by colchicine pretreatment. The ADH increase of thiourea discharge with or without colchicine led us to suppose that colchicine does not directly affect ADH action on outer membrane permeability, but exerts its effects on a site which is limiting for the ADH action on transepithelial permeability.     

Catalase activity in skeletal muscle of varying fibre types

Summary Slow oxidative skeletal muscles of rats and hamsters exhibit significantly greater catalase activity than fast oxidative muscles. Furthermore, regions of a single muscle may vary significantly.     

Contraction of frog stomach muscle and heart in non-ionic solutions

Zusammenfassung Herz und Magenmuskulatur des Frosches verlieren in halb-isotoner Rohrzuckerlösung innert 1 h alles Natrium. Trotzdem bleibt die spontane Kontraktilität erhalten. Natrium ist also für die Erregbarkeit dieser Muskeln nicht Voraussetzung.     

Membrane constants and sodium conductance of a single muscle fibre

Riassunto Nella singola fibra muscolare di cavia a 38°C sono state determinate, applicando la «square pulse analysis», la resistenza, la costante di tempo, la costante di spazio e la capacità della membrana a riposo. È stato inoltre possibile calcolare la massima conduttanza per il sodio,gn a, che è risultata di 35,3 mmho/cm².