RESUMEN
It has been shown that a step-like superprecipitation of actomyosin is determined by parallel processes of two types of superprecipitation: "immediate", which is characterized by a rapid one-step increase in turbidity, and "spontaneous", when slow increase growth of turbidity follows a clear phase. It is suggested that this phenomenon is based on heterogeneous nature of particle sizes in the original suspension, which, under certain conditions, leads to "constriction" of larger particles and "clearing" of smaller ones.
Asunto(s)
Actomiosina/química , Animales , Precipitación Química , Cinética , Músculos/química , Conejos , RatasRESUMEN
Increase in the asymmetry of light scattering diagram of myofibril suspensions resulting from their relaxation was shown to be not associated with essential alterations of the myofibrillar size. Optical changes caused by relaxation appear to be conditioned by the inner rearrangement of the myofibrillar structure.
Asunto(s)
Luz , Miofibrillas , Dispersión de Radiación , Animales , Modelos Teóricos , Conejos , SuspensionesRESUMEN
Aggregation of contracted myofibrils was studied as a function of experimental conditions at myofibril contraction. The aggregation rate increased at higher concentrations of suspensions and at increased ionic strength of the medium to achieve the maximum at 0.1 M KCL in the last case. The aggregate sizes grow with an increase of ionic strength and concentration of MgATP and reduce with addition of F-actin. Aggregation of myofibrils develops only in the case of their complete or significant contraction. It was suggested that aggregation is stimulated by dehydration of myofibril at contraction.
Asunto(s)
Contracción Muscular , Miofibrillas , Actinas/farmacología , Adenosina Trifosfato/farmacología , Técnicas In Vitro , Miofibrillas/efectos de los fármacos , Concentración OsmolarRESUMEN
Aggregation of contracted myofibrils was shown to be responsible for spontaneous: slow reduction of optical density of myofibril suspension on the final stage of their contraction. This effect faded with an increase in light wavelength, with increased angle of view of the photocell and diminished sizes of myofibrils.
Asunto(s)
Contracción Muscular , Miofibrillas/fisiología , Óptica y Fotónica , Actomiosina/metabolismo , Adenosina Trifosfato/metabolismo , Adenosina Trifosfato/farmacología , Animales , Técnicas In Vitro , Cinética , Contracción Muscular/efectos de los fármacos , Miofibrillas/efectos de los fármacos , Conejos , Espectrofotometría UltravioletaRESUMEN
An angle diagram of light scattering of myofibril suspensions was extremely asymmetric in the range of 0.05 to 10 degrees. The extent of asymmetry increased at relaxation and sharply decreased at contraction of myofibrils. Angle diagrams for myofibril light scattering calculated according to the approximate formulae of Mie theory, were close to those obtained in the experiment. It was shown that a high extent of asymmetry of calculated diagrams is determined by a low refractive index of myofibrils rather than by great dimensions of myofibrils. It is supposed that changes in the shape of scattering diagram and in other optical characteristics of myofibril and actomyosin suspensions associated with changes in their functional states depend mostly upon changes in the inner arrangement of particles rather than in their dimensions.