Activation of the contractile mechanism in the anterior byssal retractor muscle of Mytilus edulis.

Sugi, Haruo; Yamaguchi, Tomohiro

doi:10.1113/jphysiol.1976.sp011383

Cited by 53 publications

(19 citation statements)

References 33 publications

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“…ACh-elicited contractions in E l are also more dependent on extracellular calcium than in the ABRM. ACh-elicited contractions in E l fail within one to two minutes in zero calcium (Ram et al, 19841, whereas even after 10 min in zero calcium, ACh-elicited contractions of ABRM can still be obtained (Sugi and Yamaguchi, 1976). Histological studies of ABRM show that calcium in resting fibers is observed at the inner surfaces of the sarcolemma, in vesicles, and in mitochondria, whereas during ACh-elicited contractions calcium becomes diffusely distributed throughout the cytoplasm (Atsumi and Sugi, 1976).…”

Section: Discussionmentioning

confidence: 99%

Regulation of calcium influx into buccal muscles of Aplysia by acetylcholine and serotonin

Ram

Parti

1985

J. Neurobiol.

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Acetylcholine (ACh) causes contraction of Aplysia buccal muscles E1 and I5, and serotonin (5-hydroxytryptamine, 5-HT) enhances ACh-elicited contractions of these muscles. Possible roles of calcium influx in mediating these responses were examined by studying influx of 45Ca++. 5-HT increased calcium influx into both I5 and E1. Maximal influx occurred at 10(-6) M 5-HT and the increased influx could be sustained in the presence of 5-HT for at least 10 min. ACh also caused calcium influx, and calcium influx increased approximately in proportion to log[ACh] from 10(-5) M to 10(-3) M ACh. 5-HT and ACh probably bring about calcium influx by different mechanisms since the effect of ACh was additive to a maximal 5-HT response, and 10(-4) M hexamethonium bromide inhibited the increased influx caused by ACh but did not affect influx caused by 5-HT. Cyclic AMP analogues and forskolin neither caused an increase in calcium influx nor an increase in the influx caused by ACh. The data support a model in which ACh-elicited contractions of I5 and E1 are due primarily to calcium entry across the extracellular membrane, and 5-HT can "load" an intracellular site by a mechanism different from that activated by ACh. The data do not support a role for cyclic AMP in mediating the calcium influx response to 5-HT.

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Section: Discussionmentioning

confidence: 99%

Regulation of calcium influx into buccal muscles of Aplysia by acetylcholine and serotonin

Ram

Parti

1985

J. Neurobiol.

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“…2 and 3) have shown that the LBWM fibers contain a large amount of intracellularly stored Ca, which can be released by a sufficient membrane depolarization or by rapid cooling, so that the contractile mechanism can still be fully activated by 400 mM K when the Ca influx is inhibited with Mn ions or low pH, or by rapid cooling even when the depolarization-Ca release coupling is severed by a prolonged soaking in Cafree medium. In contrast with the LBWM, the Kcontracture tension in MytUus ABRM is markedly reduced by Mn ions or low pH, though the ABRM fibers are also shown to contain the intracellularly stored Ca in an amount enough to fully activate the contractile mechanism (25,28). The LBWM fibers were found to contain abundant SR located mostly near the fiber surface and the surface tubules formed by the extensive invagination of the plasma membrane (9,10).…”

Section: Neuromuscular Junctionmentioning

confidence: 99%

“…The LBWM preparation was mounted horizontally in an acrylite chamber (5 ml), which was divided into three compartments by removable partitions with Vaselinelined slits (25). The central compartment was filled with isotonic sucrose solution, while the two end compartments were filled with the experimental solution and isotonic KC1 solution, respectively; the demarcation potential between the KCl-depolarized and the experimental solution segments of the preparation was recorded with a pair of Ag-AgC1 electrodes.…”

Section: Physiological Studiesmentioning

confidence: 99%

“…The central compartment was filled with isotonic sucrose solution, while the two end compartments were filled with the experimental solution and isotonic KC1 solution, respectively; the demarcation potential between the KCl-depolarized and the experimental solution segments of the preparation was recorded with a pair of Ag-AgC1 electrodes. In the resting preparation, this potential reached a steady level of 20-30 mV within 30-60 min, and the changes in the potential were regarded as a measure of true membrane potential changes (25,27). The isometric tension developed in the experimental solution segment was recorded with a strain gauge (U-gauge, Shinko Tsushin Co., Zushi-shi, Kanagawa-ken, Japan).…”

Section: Physiological Studiesmentioning

confidence: 99%

“…Recent physiological experiments on the anterior byssal retractor muscle (ABRM) of a lamellibranch mollusc, Mytilus edulis, showed that the ABRM contains the intracellularly stored Ca in an amount enough to fully activate the contractile mechanism (24,25). Further ultrastructural and histochemical studies on the ABRM indicated that the Ca localized at the inner surface of the plasma membrane, the SR and the mitochondria is released into the myoplasm during mechanical activity (1,2,22), providing evidence that these intracellular structures are involved in the contractionrelaxation cycle.…”

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confidence: 99%

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Ultrastructural and physiological studies on the longitudinal body wall muscle of Dolabella auricularia. I. Mechanical response and ultrastructure.

Sugi¹,

Suzuki²

1978

The Journal of Cell Biology

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The physiological properties of mechanical response and the ultrastructure in the longitudinal body wall muscle (LBWM) of the opisthobranch mollusc Dolabella auricularia were studied to obtain information about excitation-contraction coupling in somatic smooth muscles responsible for smooth and slow body movement of molluscans. The contracture tension produced by 400 mM K was not affected by Mn ions (5-10 mM) and low pH (up to 4.0), but was reduced by procaine (2 mM). The K-contracture tension was not readily eliminated in a Ca-free solution containing ethylene glycol-bis(/3-aminoethyl ether)N,N,N',N'-tetraacetate (EGTA). A large contracture tension was also produced by rapid cooling of the surrounding fluid from 20 ~ to 5~176 even when the preparation showed no mechanical response to 400 mM K after prolonged (more than 2 h) soaking in the Ca-free solution. These results indicate that the LBWM fibers contain a large amount of intracellularly stored Ca which can be effectively released by membrane depolarization. The fibers were connected with each other, forming the gap junctions, the desmosomes, and the intermediate junctions. The sarcoplasmic reticulum (SR) consisted of vesicular and tubular elements, and was mostly located near the fiber surface. The plasma membrane showed marked tubular invaginations of 600-800 A in diameter, with many branches (surface tubules), extending inwards for -2/xm. These surface tubules were closely apposed to the SR, and the bridgelike structures analogous to those in the triadic junction of vertebrate skeletal muscle were observed in the space between the surface tubules and the SR. It is suggested that the influence of membrane depolarization is transmitted inwards along the surface tubules to cause the release of Ca from the SR.KEY WORDS molluscan smooth muscle mechanical response excitation-contraction coupling ultrastructure cell junctions sarcoplasmic reticulum It is generally accepted that, in vertebrate faststriated muscle, the contraction-relaxation cycle is regulated by the release of Ca from, and uptake J. CELL BIOLOGY 9 The Rockefeller University Press 9

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Comparative characteristic of Mytilus muscle cells developed in vitro and in vivo

2003

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The mussel cells from premyogenic larval stages are capable of differentiation into smooth muscle cells in vitro. However, the behavior and protein composition of these cells are not completely identical to those of smooth muscle cells of adult mussels. In this study we compared some properties of mussel muscle cells forming from cells of trochophore (premyogenic larval stage) in vitro with those of muscle cells of veliger and adult mussel. We found a substantial difference between the contractile apparatus protein composition of veliger muscle and cultivated cells. Myorod, one of the molecular markers of the phenotype of mollusc smooth muscle cells (Shelud'ko et al., 1999, Comp Biochem Physiol 122:277-285), is not a constituent of the contractile apparatus of veliger muscle. At the same time the protein composition of contractile apparatus in cultivated cells was similar to that of adult Mytilus muscles. There were only few quantitative differences between them. The contractile activity of cultivated cells was changing in time. The kinetic parameters of first spontaneous contractions were similar to those of phasic contractions, while their period was close to that of tonic contractions. After 50-55 hrs cultivation the cells produced both phasic and tonic contractions, but the character of contractile activity of cultivated cells was regulated after six days of cultivation only. However, there were no muscle cells in vitro, whose contractile activity was similar to that of veliger muscle cells. So, we concluded that properties of muscle cells forming from premyogenic larval mussel cells in culture are similar to those of muscle cells of the adult mussel, but not of veliger.

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Activation of the contractile mechanism in the anterior byssal retractor muscle of Mytilus edulis.

Cited by 53 publications

References 33 publications

Regulation of calcium influx into buccal muscles of Aplysia by acetylcholine and serotonin

Regulation of calcium influx into buccal muscles of Aplysia by acetylcholine and serotonin

Ultrastructural and physiological studies on the longitudinal body wall muscle of Dolabella auricularia. I. Mechanical response and ultrastructure.

Comparative characteristic of Mytilus muscle cells developed in vitro and in vivo

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