The long-term objective of this work is to relate the physiological properties of muscle fibers to their biochemical composition. A special feature of the proposed work is that it will be carried out on single muscle fibers (skeletal) or small bundles of muscle fibers (cardiac). This approach is necessary because it is now known that whole muscles are heterogeneous with respect to their biochemical and structural properties. Previous work in this laboratory has established considerable expertise in the area of muscle fiber physiology. More recent work has advanced this laboratory's capability in the biochemical domain to the level at which is now possible to carry out subsequent biochemical analysis of the same small piece of muscle sample used to obtain physiological measurements. The major problem to be addressed concerns the influence of myosin isozyme heterogeneity, or myosin """"""""polymorphism"""""""", on the contractile properties of muscle samples. There has been a rapid increase in the number of known myosin isozymes, and, furthermore, it is now known that even individual fibers and muscles within a given species can have a broad spectrum of myosin types. Moreover, it is now also known that a considerable """"""""plasticity"""""""" exists in myosin isozymes reflected in a succession of different phenotypes during development and response to altered """"""""loading"""""""". However, a fundamental problem is now revealed concerning the physiological relevance of these various myosin isozymes. In order to solve this crucial problem, it is proposed to carry out physiological measurements on small muscle samples and then subject these same samples to biochemical analysis consisting of both native and SDS gel electrophoresis in order to determine the myosin isozyme pattern present. In this way, it will be possible to correlate directly physiological properties with myosin isozyme content. A further novel and important feature of the proposed work is the intent to use human muscle samples in the proposed work. This is necessary, not only for health relatedness considerations, but also because it is becoming increasingly clear that extrapolation of human muscle properties from animal work is not always possible, as is now apparent from recent work on myosin isozymes in animal and human hearts.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL035032-04
Application #
3348534
Study Section
Physiology Study Section (PHY)
Project Start
1985-03-01
Project End
1990-02-28
Budget Start
1988-03-01
Budget End
1989-02-28
Support Year
4
Fiscal Year
1988
Total Cost
Indirect Cost
Name
Brigham and Women's Hospital
Department
Type
DUNS #
071723621
City
Boston
State
MA
Country
United States
Zip Code
02115
Jiang, Y; Julian, F J (1999) Effects of ramp shortening during linear phase of relaxation on [Ca2+]i in intact skeletal muscle fibers. Am J Physiol 276:C152-60
Claflin, D R; Morgan, D L; Julian, F J (1998) The effect of length on the relationship between tension and intracellular [Ca2+] in intact frog skeletal muscle fibres. J Physiol 508 ( Pt 1):179-86
Vandenboom, R; Claflin, D R; Julian, F J (1998) Effects of rapid shortening on rate of force regeneration and myoplasmic [Ca2+] in intact frog skeletal muscle fibres. J Physiol 511 ( Pt 1):171-80
Morgan, D L; Claflin, D R; Julian, F J (1996) The effects of repeated active stretches on tension generation and myoplasmic calcium in frog single muscle fibres. J Physiol 497 ( Pt 3):665-74
Claflin, D R; Morgan, D L; Stephenson, D G et al. (1994) The intracellular Ca2+ transient and tension in frog skeletal muscle fibres measured with high temporal resolution. J Physiol 475:319-25
Morgan, D L; Claflin, D R; Julian, F J (1991) Tension as a function of sarcomere length and velocity of shortening in single skeletal muscle fibres of the frog. J Physiol 441:719-32
Herland, J S; Julian, F J; Stephenson, D G (1990) Unloaded shortening velocity of skinned rat myocardium: effects of volatile anesthetics. Am J Physiol 259:H1118-25
Morgan, D L; Claflin, D R; Julian, F J (1990) Tension in frog single muscle fibers while shortening actively and passively at velocities near Vu. Biophys J 57:1001-7
Herland, J S; Julian, F J; Stephenson, D G (1990) Halothane increases Ca2+ efflux via Ca2+ channels of sarcoplasmic reticulum in chemically skinned rat myocardium. J Physiol 426:1-18
Claflin, D R; Morgan, D L; Julian, F J (1990) Earliest mechanical evidence of cross-bridge activity after stimulation of single skeletal muscle fibers. Biophys J 57:425-32

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