Contractile filaments in cells of regenerating tendon

Summary An extensive cytoplasmic fibrillar system has been observed in fibroblast-like cells of regenerating tendon. It consists of bundles of actin filaments, which often show a cross-striated appearance due to electron dense bodies occurring throughout their length. The functional role of this contractile apparatus seems to be related to the process of movement and orientation of the newly formed cells and to the retraction of the regenerating tendon.Work was supported by grant C. N. R. n. 75.01224.04–115.5479 from Consiglio Nazionale delle Ricerche, Italy.The authors are grateful to Dr G. F. Bottazzo, Dept. Immunology, Middlesex Hospital, London, for carrying out the absorption experiments with purified actin and to Miss M. Rita Nicotra, Miss Laura M. Vassallo and Mr Mario Termine for their technical assistance.     

Tension and structure in crustacean fast and slow muscle fibres

Résumé Les fibres de l'abdomen du homard pourvues de longues striations ont développé une plus grande tension par unité de surface, en coupe transversale, que les fibres munies de striations courtes.     

Ultra-structural specificity in regenerating smooth muscle

Zusammenfassung Elektronenmikroskopisch wird erstmals die Regeneration von glatten Muskelzellen in vivo beschrieben und festgestellt, dass diese Zellen entgegen der herrschenden Auffassung keine Differenzierung durchmachen, bevor sie sich teilen.

---

---

I thank Prof.D. Allbrook, of this Department, for his guidance in the preparation of this paper. This work is supported by the National Health and Medical Research Council of Australia.     

Induced myotonia in fast and slow muscles of the rat

Zusammenfassung Nach chronischer Applikation von 25-Azacholesterol kann auch in den langsamen Muskelfasern Myotonie erzeugt werden.     

Differential response of myosin — ATPase activity and contraction properties of fast and slow rabbit muscles following denervation

Zusammenfassung Nachweis unterschiedlicher Kontraktionsgeschwindigkeiten bei schnellen und langsamen Kaninchenmuskeln sowie entsprechende Unterschiede in der Myosin-ATPase-Aktivität und im Spektrum niedermolekularer Proteine nach Denervation werden gezeigt.

---

---

We are indepted to MissA. Krejová and Mrs.A. Herbrychová for their valuable and skillfull technical assistance.     

Effects of the spinal cord section and of subsequent denervation on the mechanical properties of fast and slow muscles

Summary The Soleus muscle of the rat, 3–6 months old, becomes significantly faster than in the controls, if the spinal cord is cut at birth. Mechanical properties of Extensor Digitorum Longus (EDL) muscle are not altered by spinal cord section. In cordotomized animals Soleus muscle always remains slower than EDL muscle. Denervation, performed 3–6 months after birth, has the same slowing effects in the Soleus and EDL muscles, both in cordotomized and in the control animals.     

Effects of the spinal cord section and of subsequent denervation on the mechanical properties of fast and slow muscles.

The Soleus muscle of the rat, 3--6 months old, becomes significantly faster than in the controls, if the spinal cord is cut at birth. Mechanical properties of Extensor Digitorum Longus (EDL) muscle are not altered by spinal cord section. In cordotomized animals Soleus muscle always remains slower than EDL muscle. Denervation, performed 3--6 months after birth, has the same slowing effects in the Soleus and EDL muscles, both in cordotomized and in the control animals.     

The effect of the venom of the digger wasp Philanthus on the fast and slow excitatory and the inhibitory system in the locust muscle

Zusammenfassung Es wird gezeigt, dass das Gift der Wespe Philanthus triangulum F. bei der Heuschrecke eine reversible Muskellähmung bewirkt, die auf einer Blockierung der Axon-Muskel-Synapse der «schnellen» Faser beruht. Die Synapse der langsamen und hemmenden Faser wird offenbar nicht beeinflusst.

---

---

This work has been supported in part by the European Research Office, United States Army, Frankfurt am Main, Germany.

---

Acknowledgments: I am indebted to Prof. Dr. C.van der Meer for his constant help and criticism and to Dr. R. T.Simon Thomas for providing the wasps. I wish to thank Mr. E.Engels for all the technical work.     

Biochemical efficiency and intrinsic shortening speed in selected vertebrate fast and slow muscles

Summary The biochemical efficiency was measured in iodoacetate N₂ and NaCN-treated muscles by dividing the work done by the amount of phosphoryl creatine hydrolysed when contracting at their optimum velocity. An inverse relationship was found between the intrinsic speed of shortening (V_max) of the muscles and their mechanochemical efficiency.     

Effects of barium on separately recorded fast and slow PIII responses in bullfrog retina

Investigation of Ba2+ effects on fast and slow PIII responses in isolated bullfrog retina revealed that Ba2+ suppressed slow PIII completely with little effect on fast PIII. A light-induced [K+]0 decrease in the photoreceptor layer was observed in spite of Ba2+ perfusion, indicating the suppressive action of Ba2+ on the K+ conductance of the Müller cell membrane.     

Effects of barium on separately recorded fast and slow PIII responses in bullfrog retina

Summary Investigation of Ba²⁺ effects on fast and slow PIII responses in isolated bullfrog retina revealed that Ba²⁺ suppressed slow PIII completely with little effect on fast PIII. A light-induced [K⁺]₀ decrease in the photoreceptor layer was observed in spite of Ba²⁺ perfusion, indicating the suppressive action of Ba²⁺ on the K⁺ conductance of the Müller cell membrane.Acknowledgment. This work was supported by research grant from the Ministry of Education, Science and Culture of Japan and Kinki University research grant 55–103. The author wishes to thank Prof. I. Hanawa at Kobe University for his valuable discussions.     

Myosin heavy chains in fast skeletal muscle of chick embryo

Summary The peptide map obtained by electrophoresis after digestion of purified myosin heavy chains from pectoralis muscle of embryonic chicken with theStaphylococcus aureus V8 protease, produces a peptide pattern very similar but not identical to that of adult fast myosin. In fact, some components that are present in a small amount in the map of slow adult myosin are visible in the embryonic pattern.Acknowledgments. I wish to acknowledge the enthusiastic encouragement of Dr Ugo Carraro and the help of Prof. Stefano Schiaffino's group and of Dr Marcello Cantini for embryonic tissue isolation. The skillful technical assistance of Mr Silvio Belluco is also gratefully acknowledged. This work was supported in part by a grant of Muscular Dystrophy Association of America to Prof. Massimiliano Aloisi.     

Differential effects of disuse preceding denervation on the onset and development of fibrillation in fast and slow muscles

Summary Section of the sciatic nerve, performed after a week of muscular disuse, is followed by fibrillation earlier in the soleus (S) than in the anterior tibialis (AT) muscle of the rat. The subsequent development of fibrillation, which is different in the control denervated S as compared with the control denervated AT, tends to become similar in the disused-denervated muscles.This work was aided, in part, by a grant from U. I. L. D. M. (Unione Italiana Lotta alla Distrofia Muscolare), Sezione di Trieste.     

Differential binding of vitamin E to sarcoplasmic reticulum from fast and slow muscles of the rabbit

Summary The distribution of [³H]-tocopherol between the intracellular membranes of fast white and slow red muscles was studied in vivo. In vitro experiments confirmed a higher incorporation of the vitamin into the reconstructed sarcoplasmic reticulum membranes from slow muscle.This work was supported by funds from the Consiglio Nazionale delle Ricerche to the C.S. Biologia e Fisiopatologia Muscolare and to the Istituto di Patologia Generale, Università di Bologna, and in part by a grant from the Muscular Dystrophy Association to Prof. Aloisi.     

On the origin of the Mg++-activated ATPase of muscle mitochondrial preparations

Riassunto Nelle preparazioni mitocondriali di muscolo è presente una notevole attività ATPasica stimolata dal Mg⁺⁺, anche se i mitocondri sono intatti e ben fosforilanti. Questa attività ATPasica, stimolata da Mg⁺⁺, appare essere inibita dall'aggiunta di Ca⁺⁺. Poichè questo comportamento è tipico della attività ATPasica associata ai microsomi, gli autori concludono che l'attività ATPasica stimolata da Mg⁺⁺ delle preparazioni mitocondriali di muscolo è molto probabilmente espressione di un inquinamento delle preparazioni stesse da parte di frammenti originanti dal reticolo sarcoplasmico.     

Effect of lidoflazine on norepinephrine,angiotensin and serotonin responses in isolated smooth muscle preparations

Résumé Les effets de la lidoflazine ont été étudiés sur les bandelettes aortiques isolées du lapin et les bandelettes gastriques isolées du rat. La lidoflazine antagonise significativement la sérotonine sur ces 2 préparations sans altérer leurs réponses à l'angiotensine et à la noradrénaline.