补充糖-蛋白质饮料对耐力性运动的影响

肌糖原是人体内重要的能源物质,肌糖原贮量的多少直接影响到长时间耐力性项目的运动能力。通过提高肌糖原的贮备可改善和提高耐力性项目的运动能力,过去通常采用高糖膳食的方法来提高糖原贮备,最新的研究发现,通过在糖饮料中添加蛋白质成分,能够更为有效的增加体内糖原贮备,从而提高耐力性项目的运动成绩。     

Microinjection of synthetic protein kinase inhibitor into single barnacle muscle fibers before and after cyclic AMP

Summary Single muscle fibers from the barnacleBalanus nubilus have been used as a preparation to see if a synthetic 20-residue PKI (5-24)-peptide is able to block or reverse the stimulatory response of the ouabain-insensitive Na efflux to injected cAMP. The results obtained show that this peptide behaves as a powerful inhibitor of the cAMP-mediated response and is also able to partially reverse the sustained stimulation of the Na efflux observed in ouabain-poisoned fibers following the injection of subunit A of cholera toxin.Warmest thanks to Prof. E. H. Fischer and Kurt Diltz for a sample of sPK1. This work received support from NSF, the Graduate School Research Committee and from NIH through a General Research Support Grant to the University of Wisconsin Medical School.     

Native skeletal muscle dihydropyridine receptor exists as a supramolecular triad complexRID="†"ID="†" Research Article

One of the central elements of excitation-contraction coupling, the voltage-sensing dihydropyridine receptor, is believed to exist as a high-molecular-mass complex in the triad junction. Although freeze-fracture electron microscopical analysis suggests a tetrad complex, no direct biochemical evidence exists demonstrating the actual size of the native membrane complex. Using a combination of various two-dimensional gel electrophoresis techniques, we show here that the principal α ₁-subunit of the dihydropyridine receptor and its auxiliary α ₂-subunit form a triad complex of approximately 2800 kDa under native conditions. Established Ca²⁺-ATPase tetramers and calsequestrin monomers were employed for the internal standardization of the gel systems used. Thus, the large voltage-sensing complex appears to be tightly associated, since it does not disintegrate during subcellular fractionation and native electrophoresis procedures. Our findings support the cell biological hypothesis that native dihydropyridine receptor units form a tetrad structure within the transverse tubules. Received 10 October 2000; revised 28 November 2000; accepted 4 January 2001     

Is glycogen a major energy source in avian gizzard smooth muscle contraction?

Summary In comparison to other avian smooth and striated muscles, chicken gizzard contains very low levels of glycogen. This myoglobin-rich muscle seems to derive the energy for its powerful contraction from other sources.Support by the Deutsche Forschungsgemeinschaft (Ste 105/25-2) is gratefully acknowledged.     

In vitro stability and protein composition of thick filaments from insect flight muscles

Thick and thin filaments of synchronous and asynchronous insect flight muscles were separated by density gradient centrifugation. A good release of myofilaments from myofibrils was obtained by sonication of myofibrils in relaxing solution with pH 6.1 (locust), pH 6.4 (honeybee) and pH 6.6 (fleshfly), respectively. Thick filaments but not thin filaments were dissolved, if sucrose gradient centrifugation was used to separate the filaments. Thus, sucrose gradients are the medium of choice if actin filaments are to be purified. Glycerol-containing gradients selectively dissolved myosin filaments from fleshfly muscles. The stability of the myosin filaments of all muscles was sufficient in gradients with 10–30% formamide.     

高维空间中几类可嵌入连续流或半流的自映射

给出了高维空间中几类可嵌入连续流和半流的自映射的特征。     

Serum creatine kinase in marathon runners

Summary Serum creatine phosphokinase (CK) and CK-MB activity were determined in 21 trained runners participating in a marathon race (42.2 km). Enzyme activities immediately after the race increased two to three times compared with activities before the race. The greatest increases were found in the slowest runners, suggesting greater skeletal muscular trauma in the least trained or fit. As these are likely to include the older athletes who are also more likely to suffer acute myocardial injury during strenuous exercise, our findings assume special import in the interpretation of increased CK and CK-MB serum activities of older athletes.Acknowledgments. The authors wish to thank the members and president of the Columbia Track Club for their cooperation.     

Effect of phosphorylation of myosin light chains on interaction of heavy meromyosin with regulated F-actin in ghost fibers

Summary The binding of phosphorylated heavy meromyosin to regulated F-actin in ghost fibers at high Ca²⁺ concentration increases, and at low Ca²⁺ concentration decreases, the anisotropy of intrinsic tryptophan fluorescence of F-actin. The effect is opposite to the effect of the binding of dephosphorylated heavy meromyosin.     

机敏材料用聚合物凝胶

简单介绍了机敏材料的基本概念和主要用途,并对各种聚合物凝胶进行了系统的评述。