The origin of the instantaneous elasticity in single frog muscle fibres

Summary High-speed cinematographic recordings of single tetanized muscle fibres during a quick decrease in length revealed that the shortening was mostly localized at the fibre segment nearest the released end of the fibre, indicating that the instantaneous elasticity may not originate from the elasticity of the cross-bridges.We wish to thank Dr H. Hashizume of the Engineering Research Institute, Tokyo University for providing facilities to use the ultra high-speed cinecamera, and Mr T. Tsuno, Mr Y. Nakamura and Miss S. Gomi for their technical assistance.     

The origin of the instantaneous elasticity in single frog muscle fibres.

High-speed cinematographic recordings of single tetanized muscle fibres during a quick decrease in length revealed that the shortening was mostly localized at the fibre segment nearest the released end of the fibre, indicating that the instantaneous elasticity may not originate from the elasticity of the cross-bridges.     

Birefringence signals and tension development in single frog muscle fibres at short stimulus intervals

Summary The early large birefringence signal and mechanical activity were studied together in isolated single fibres of frog skeletal muscle with double stimulation at short stimulus intervals (2–60 msec) at room temperature and at 4–6°C. In all fibres tested, extra tension and additional birefringence signal in response to the second stimulus appeared simultaneously and suddenly upon increasing the stimulus interval. The shape of the stimulus-interval versus tension-development curve makes it highly improbable that subthreshold calcium release occurs at shorter stimulus intervals; therefore, tension development reliably reflects Ca-release in these experiments. In contrast to the report by Suarez-Kurtz and Parker, birefringence signal and calcium release are shown not to be dissociated by double stimulation. This result supports the hypothesis that the early large birefringence signal is an intrinsic indicator of calcium release from the sr during EC-coupling in skeletal muscle.     

Electron microscope and optical diffraction studies on glycerol-extracted insect flight muscle fibres relaxed by pyrophosphate

Zusammenfassung Elektronenmikroskopische Aufnahmen von einfacher Filament-Lagen Mg-Pyrophosphaterschlaffter Fasern der dorsolongitudinalen Flugmuskulatur vonLethocerus spec. gleichen weitgehend dem Bild ATP-erschlaffter Muskeln. Optische Transformationen scheinen dagegen die Charakteristika von ATP-erschlafften Fasern und solchen, die sich im Rigor mortis befinden, zu kombinieren. Die Überführung der Fasern aus einer Mg-Pyrophosphat- in eine Rigor-Lösung stellte das Rigor-Muster wieder her.

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Supported by a short term fellowship of the EMBO to one of us (G.B.).

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Acknowledgment. We are greatly indebted to Dr.Louise N. Johnson, P. Eagle andL. J. Stumpp, Oxford, Dept. of Zoology, for their help with the optical diffraction measurements, to Mrs.Hiltrud Gülker for her expert technical assistance and to Prof.Pringle and Dr.R. T. Tregear for their hospitality and many helpful discussions and criticism.     

Birefringence signals and tension development in single frog muscle fibres at short stimulus intervals.

The early large birefringence signal and mechanical activity were studied together in isolated single fibres of frog skeletal muscle with double stimulation at short stimulus intervals (2-60 msec) at room temperature and at 4--6 degrees C. In all fibres tested, extra tension and additional birefringence signal in response to the second stimulus appeared simultaneously and suddenly upon increasing the stimulus interval. The shape of the stimulus-interval versus tension-development curve makes it highly improbable that subthreshold calcium release occurs at shorter stimulus intervals; therefore, tension development reliably reflects Ca-release in these experiments. In contrast to the report by Suarez-Kurtz and Partker, birefringence signal and calcium release are shown not to be dissociated by double stimulation. This result supports the hypothesis that the early large birefringence signal is an intrinsic indicator of calcium release from the sr during EC-coupling in skeletal muscle.     

Effect of glycerol treatment on sodium and potassium in isolated muscle fibres of the frog

Summary The sodium concentration in single frog muscle fibres vacuolated by glycerol treatment was significantly higher than in devacuolated fibres. Intracellular potassium concentration did not show any significant change. It is concluded that the transverse tubular system forms vacuoles with a high NaCl concentration upon glycerol removal.     

The length-tension diagram of single muscle fibres of the crayfish

Zusammenfassung An isolierten Muskelfasern vonAstacus fluviatilis wurde mittels Kaliumkontraktur die Spannung-Sarkomerlängenrelation untersucht. Maximale Faserspannung wird bei einer Sarkomerlänge von 10,5 entwickelt. Werden Fasern zu einer Sarkomerlänge von 16,5 gedehnt, so ist die Spannung nicht mehr messbar. Diese Sarkomerlänge ist etwas grösser als diejenige (14.45), die aus der Länge der dicken Filamente (3.95) und der optimalen Länge hervorgeht.     

Increase in muscle fibres in the lateralis muscle (white portion) of Mugilidae (Pisces,Teleostei)

Summary A cycle of postlarval growth is described in the white portion of the lateralis muscle of Mugilidae. The cycle was identified histochemically by the myosin-ATPase reaction.This work was supported by a CNR grant (Oceanografia e fondi marini project).     

The origin of the series elastic component in single crayfish muscle fibres

Summary High-speed cinematographic studies on the length changes of single tetanized crayfish muscle fibres during a step decrease in length revealed a fairly uniform distribution of a highly compliant series elastic component along the fibre length, suggesting that it mainly originates from some structures in each sarcomere other than the cross-bridges.We wish to thank Dr H. Hashizume of the Engineering Research Institute, Tokyo University for providing facilities to use the ultra high-speed cine-camera, and Mr T. Tsuno, Mr Y. Nakamura and Miss S. Gomi for their technical assistance.     

Simultaneous measurement of velocities of adjacent sacromere length changes in single muscle fibres

Zusammenfassung Messmethode für die Sarkomerenlänge der gestreiften Einzelmuskelfaser. Bei elektrischer Reizung verkürzen sich benachbarte Sarkomere ja nach Ausgangslänge und benachbarte Z-Linien bewegen sich mit verschiedenen Geschwindigkeiten selbst unter «isometrischen» Bedingungen.

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This study was supported in part by a grant from the China Medical Board (Grant No. 72-281) and also by a grant from the Higher Degree and Research Committee of the University of Hong Kong. We wish also to express our gratitude to Prof.K. K. Cheng for his encouragement in this study.     

Tension transients in glycerol-extracted fibres of insect fibrillar muscle(Lethocerus maximus)

Zusammenfassung Mit Wasser-Glyzerin extrahierte fibrilläre Muskelfasern (Fasermodelle) vonLethocerus maximus zeigen im ATP-Bad nach plötzlicher Dehnung das Phänomen der Dehnungsaktivierung, gefolgt von einer gedämpften, temperaturabhängigen isometrischen Oszillation der Kontraktionsspannung. Die Frequenz entspricht offenbar der Eigenfrequenz zyklisch tätiger « KontraktionsbrÜcken » zwischen Aktin und Myosin.

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Supported by Grant No. RU 154/1 of the Deutsche Forschungsgemeinschaft.     

The origin of the series elastic component in single crayfish muscle fibres.

High-speed cinematographic studies on the length changes of single tetanized crayfish muscle fibres during a step decrease in length revealed a farily uniform distribution of a highly compliant series elastic component along the fibre length, suggesting that it mainly originates from some structures in each sarcomere other than the cross-bridges.     

Electron diffraction and electron microscopy studies on the crystalline component of enamel of theOdontaspis (selachii)

Résumé L'auteur constate que dans la dent du Requin du genreOdontaspis l'ultrastucture de la substance qui recouvre la dentine est morphologiquement très semblable à celle de l'émail de la dent humaine. Par diffraction électronique le composant cristallin de l'émail du Requin a été déterminé comme étant del'apatite. Ces résultats montrent que le revêtement externe de la dent d'Odontaspis peut être considéré comme un véritable émail.     

The effect of vinblastin and vincristin on single nerve fibres

Summary The perfusion of the node of Ranvier with vinblastin or vincristin reduces the amplitude of the action potential within a few seconds. Vincristins is 10fold more active than vinblastin. Upon withdrawal, the effect is promptly reversible and it is antagonized by acetylcholine.