Optimal length, calcium sensitivity and twitch characteristics of skeletal muscles from mdm mice with a deletion in N2A titin

ABSTRACTAll skeletal muscles produce their largest forces at a single optimal length, losing force when stretched or shortened. In vertebrate feeding systems, this fundamental force–length relationship translates to variation in bite force across gape, which affects the food types that can be eaten effectively. We measured the bite force–gape curves of two sympatric species: king salmon (Oncorhynchus tshawytscha) and pink salmon (Oncorhynchusgorbuscha). Cranial anatomical measurements were not significantly different between species; however, peak bite forces were produced at significantly different gapes. Maximum bite force was achieved at 67% of maximum gape for king salmon and 43% of maximum gape for pink salmon. This may allow king salmon to use greater force when eating large or elusive prey. In contrast, pink salmon do not require high forces at extreme gapes for filter feeding. Our results illustrate that the bite force–gape relationship is an important ecophysiological axis of variation.

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Use of dantrolene plus multiple pulses to detect stress-susceptible porcine muscle

Journal of Applied Physiology ◽

10.1152/jappl.1986.60.4.1313 ◽

1986 ◽

Vol 60 (4) ◽

pp. 1313-1320 ◽

Cited By ~ 9

Author(s):

J. G. Quinlan ◽

P. A. Iaizzo ◽

G. A. Gronert ◽

S. R. Taylor

Keyword(s):

Intravenous Administration ◽

Tibialis Anterior ◽

Skeletal Muscles ◽

Contractile Properties ◽

Tension Development ◽

Porcine Muscle ◽

Multiple Pulses ◽

Twitch Characteristics

Twitch characteristics of tibialis anterior muscles in situ were examined in stress-susceptible and normal swine. Three groups of pigs were studied: (1) purebred Pietrain stress-susceptible, (2) purebred Yorkshire normal, and (3) a crossbred (Pietrain-Yorkshire) litter containing both stress-susceptible and normal animals. Purebred and crossbred stress-susceptible pigs provided qualitatively similar results, as did purebred and crossbred normal pigs. Single stimuli produced greater than normal peak tensions and faster rates of tension development in stress-susceptible animals. Multiple stimuli (2–6 pulses at 5-ms intervals) increased peak tensions and rates of tension development, but did not augment differences between normal and stress-susceptible pigs. Intravenous administration of dantrolene reduced peak tensions and rates of tension development in all groups for single and multiple stimuli. However, the reduction was significantly less (P less than 0.01) for stress-susceptible pigs. Multiple stimuli (4–6 pulses) plus dantrolene amplified differences (P less than 0.01) in contractile properties between normal and stress-susceptible skeletal muscles, with stress-susceptible muscles obtaining larger peak tensions and faster rates of tension development. Normal and stress-susceptible pigs may, therefore, be distinguished by these procedures.

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Effects of perchlorate on myofibrillar calcium sensitivity in rat skinned skeletal muscles

Acta Physiologica Scandinavica ◽

10.1046/j.1365-201x.1996.183000.x ◽

1996 ◽

Vol 156 (4) ◽

pp. 447-456

Author(s):

A. KHAMMARI ◽

S. BAUDET ◽

J. NOIREAUD

Keyword(s):

Skeletal Muscles ◽

Calcium Sensitivity

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Distribution of c-protein isoforms in sarcomeres of developing chick skeletal muscle

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010010319x ◽

1988 ◽

Vol 46 ◽

pp. 226-227

Author(s):

D. A. Fischman ◽

J. E. Dennis ◽

T. Obinata ◽

H. Takano-Ohmuro

Keyword(s):

Skeletal Muscles ◽

Thick Filament ◽

Protein Isoforms ◽

Actin Binding ◽

Striated Muscles ◽

C Protein ◽

Sarcomeric Protein ◽

Thick Filaments ◽

Cross Bridges ◽

Bridge Bearing

C-protein is a 150 kDa protein found within the A bands of all vertebrate cross-striated muscles. By immunoelectron microscopy, it has been demonstrated that C-protein is distributed along a series of 7-9 transverse stripes in the medial, cross-bridge bearing zone of each A band. This zone is now termed the C-zone of the sarcomere. Interest in this protein has been sparked by its striking distribution in the sarcomere: the transverse repeat between C-protein stripes is 43 nm, almost exactly 3 times the 14.3 nm axial repeat of myosin cross-bridges along the thick filaments. The precise packing of C-protein in the thick filament is still unknown. It is the only sarcomeric protein which binds to both myosin and actin, and the actin-binding is Ca-sensitive. In cardiac and slow, but not fast, skeletal muscles C-protein is phosphorylated. Amino acid composition suggests a protein of little or no αhelical content. Variant forms (isoforms) of C-protein have been identified in cardiac, slow and embryonic muscles.

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The effect of ionophore A23178 on the α-actinin crosslinks in the z-band of frog skeletal muscle: An EM study

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100142396 ◽

1986 ◽

Vol 44 ◽

pp. 154-155

Author(s):

F.T. Llados ◽

V. Krlho ◽

G.D. Pappas

Keyword(s):

Muscle Damage ◽

Transmitter Release ◽

Skeletal Muscles ◽

Calcium Uptake ◽

Muscle Membrane ◽

Frog Skeletal Muscle ◽

Ach Release ◽

Sustained Action ◽

Calcium Deposits ◽

Intense Stimulation

It Is known that Ca++ enters the muscle fiber at the junctional area during the action of the neurotransmitter, acetylcholine (ACh). Pappas and Rose demonstrated that following Intense stimulation, calcium deposits are found In the postsynaptic muscle membrane, Indicating the existence of calcium uptake In the postsynaptic area following ACh release. In addition to this calcium uptake, when mammal Ian skeletal muscles are exposed to a sustained action of the neurotransmitter, muscle damage develops. These same effects, l.e., Increased transmitter release, calcium uptake and finally muscle damage, can be obtained by Incubating the muscle with lonophore A23178.

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