A study of frog muscle maintained in organ culture

Harris, AJ; Miledi, Ricardo

doi:10.1113/jphysiol.1972.sp009749

Cited by 40 publications

(41 citation statements)

References 25 publications

(28 reference statements)

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“…However, the persistence of m.e.p.p.s after the cessation of e.p.p.s has also been reported in degenerating neuromuscular junctions in the rat (Miledi & Slater, 1970) (Usherwood, 1963(Usherwood, , 1973 and frog muscle maintained in organ culture (Harris & Miledi, 1972). In line with the present results, the frequency of m.e.p.p.s in these degenerating junctions is also not accelerated in K+-rich medium.…”

Section: Non-transmitting Junctionssupporting

confidence: 81%

“…The length of time that neuromuscular transmission is maintained after nerve section depends on many factors, such as temperature, season, diameter of motor axons and the length of nerve left attached to the muscle (Birks et al 1960b;Miledi & Slater, 1970;Harris & Miledi, 1972). Because of this variation, neuromuscular transmission following denervation was monitored for each muscle.…”

Section: Stages Of Denervationmentioning

confidence: 99%

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Electrophysiological and freeze‐fracture studies of changes following denervation at frog neuromuscular junctions.

Ko¹

1981

The Journal of Physiology

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1. Changes which occur at frog neuromuscular junctions following denervation have been studied by combining intracellular recording and freeze‐fracture electron microscopy. 2. Shortly after nerve section, both neuromuscular transmission and intramembrane structures of neuromuscular junctions remain normal. 3. Later, neuromuscular transmission fails, beginning with the disappearance of end‐plate potentials (e.p.p.s) and followed by the disappearance of miniature end‐plate potentials (m.e.p.p.s). The frequency of m.e.p.p.s which persist after cessation of e.p.p.s is not increased dramatically in K+‐rich or hypertonic solutions. 4. Concomitant with the changes of transmission are changes in intramembrane structures. The first sign of these changes in disruption of active zones, which become disorganized, fragmented or vanish. Nerve terminals then disintegrate and eventually are engulfed by Schwann cells. 5. When neuromuscular transmission has failed completely, former sites of the neuromuscular junction are occupied by Schwann cells. These cells develop transverse ridges which lie opposed to junctional folds, just like active zones of nerve terminals. However, the ridges on Schwann cells do not contain organized rows of particles or clusters of any synaptic organelles, even at later stages when Schwann cell m.e.p.p.s commence. 6. It is suggested that the failure of e.p.p.s involves at least an impairment of the transmitter release mechanism at the nerve terminal, which is probably associated with the disruption of active zones. The cessation of m.e.p.p.s is thought to be caused by the engulfment of terminals by Schwann cells.

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Section: Non-transmitting Junctionssupporting

confidence: 81%

Section: Stages Of Denervationmentioning

confidence: 99%

Electrophysiological and freeze‐fracture studies of changes following denervation at frog neuromuscular junctions.

Ko¹

1981

The Journal of Physiology

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“…The experiments to be described were designed to determine whether or not any of these alterations could be attributed to the absence of the neurotransmitter NE from the cell's environment. The approach of organ culture, previously useful for skeletal muscle (Miledi and Trowell, 1962;Harris and Miledi, 1972), was selected to test whether: (1) portal veins denervated in vitro (Aprigliano and Hermsmeyer, 1976) and maintained in organ culture would develop the characteristic denervation changes previously observed, and (2) maintenance of the vessels in a medium containing NE would prevent the appearance of these changes.…”

Section: +mentioning

confidence: 99%

Trophic effect of norepinephrine on the rat portal vein in organ culture.

Abel

Trapani

Aprigliano

et al. 1980

Circulation Research

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SUMMARY Rat portal veins were maintained in organ culture to study the development of characteristic denervation changes and a possible trophic effect of the neurotransmitter norepinephrine (NE). Vessels maintained in organ culture for 2 days showed supersensitivity to NE and Ba 2+, a more rapid rate of relaxation from a Ba 2+ contracture, and partial depolarization of the myovascular cells. All of these changes except the quicker relaxation from Ba 2+ contracture could be prevented by incubating the preparations in a NE-containing medium. This evidence suggests that functional changes in vascular muscle cells are caused by the removal of a trophic influence of NE, but can be prevented by NE replacement. However, the failure of NE in the culture media to prevent the increased rate of relaxation from Ba 2+ contracture found after 2 days in organ culture suggests that NE is not the only trophic influence acting on the portal vein. In addition, incubation of veins in a NE-containing medium produced a marked subsensitivity to the contractile effects of NE, but not Ba 2+, and thus possible desensitization of noradrenergic receptors. The data thus support a trophic role for NE in the rat portal vein.

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“…Overton (1902) pioneered on long-term culture of skeletal muscle and showed that after 12 days of culture, frog muscle was still excitable. Several investigators attempted to improve culture conditions to maintain whole skeletal muscle of different species in culture for longer periods (e.g., Mines, 1910;Miledi & Trowell, 1962;Harris & Miledi, 1972;McDonagh, 1984;Ohira et al, 1989). Although control over the conditions of the muscle preparations was improved compared to the in vivo situation, these preparations were heterogeneous with respect to fibre length, fibre type and local extra-cellular matrix composition.…”

Section: Introductionmentioning

confidence: 99%

Twitch and Tetanic Tension during Culture of Mature Xenopus laevis Single Muscle Fibres

Jaspers¹,

Feenstra²,

Groot³

et al. 2001

Archives of Physiology and Biochemistry

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Investigation of the mechanisms of muscle adaptation requires independent control of the regulating factors. The aim of the present study was to develop a serum-free medium to culture mature single muscle fibres of Xenopus laevis. As an example, we used the culture system to study adaptation of twitch and tetanic force characteristics, number of sarcomeres in series and fibre cross-section. Fibres dissected from m. iliofibularis (n = 10) were kept in culture at a fibre mean sarcomere length of 2.3 mm in a culture medium without serum. Twitch and tetanic tension were determined daily. Before and after culture the number of sarcomeres was determined by laser diffraction and fibre cross-sectional area (CSA) was determined by microscopy. For five fibres twitch tension increased during culture and tetanic tension was stable for periods varying from 8 to 14 days ('stable fibres'), after which fibres were removed from culture for analysis. Fibre CSA and the number of sarcomeres in series remained constant during culture. Five other fibres showed a substantial reduction in twitch and tetanic tension within the first five days of culture ('unstable fibres'). After 7-9 days of culture, three of these fibres died. For two of the unstable fibres, after the substantial force reduction, twitch and tetanic tension increased again. Finally at day 14 and 18 of culture, respectively, the tensions attained values higher than their original values. For stable fibres, twitch contraction time, twitch half-relaxation time and tetanus 10%-relaxation time increased during culture. For unstable fibres these parameters fluctuated. For all fibres the stimulus threshold fluctuated during the first two days, and then remained constant, even for the fibres that were cultured for at least two weeks. It is concluded that the present culture system for mature muscle fibres allows long-term studies within a well-defined medium. Unfortunately, initial tetanic and twitch force are poor predictors of the long-term behaviour of the fibres.

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A study of frog muscle maintained in organ culture

Cited by 40 publications

References 25 publications

Electrophysiological and freeze‐fracture studies of changes following denervation at frog neuromuscular junctions.

Electrophysiological and freeze‐fracture studies of changes following denervation at frog neuromuscular junctions.

Trophic effect of norepinephrine on the rat portal vein in organ culture.

Twitch and Tetanic Tension during Culture of Mature Xenopus laevis Single Muscle Fibres

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