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Witalińaki W, Labuda H. Extraocular muscles in the lamprey,
Lampetra fluviatils
L. II. Motor end plates. J Zool (1987) 2009. [DOI: 10.1111/j.1469-7998.1985.tb04933.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- W. Witalińaki
- Institute of Zoology, Jagiellonian University, Kraków, Poland
| | - H. Labuda
- Institute of Zoology, Jagiellonian University, Kraków, Poland
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Mathiesen I, Rimer M, Ashtari O, Cohen I, McMahan UJ, Lømo T. Regulation of the size and distribution of agrin-induced postsynaptic-like apparatus in adult skeletal muscle by electrical muscle activity. Mol Cell Neurosci 1999; 13:207-17. [PMID: 10328882 DOI: 10.1006/mcne.1999.0744] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
We compared actylcholine receptor (AChR) aggregates induced by neural agrin released from transfected muscle fibers with AChR aggregates induced by transplanted axons in extrajunctional regions of denervated rat soleus muscles. Both neural agrin and transplanted axons induced multiple, irregularly distributed AChR aggregates on muscle fibers. Direct electrical muscle stimulation of transfected muscles for up to 10 weeks removed all agrin-induced AChR aggregates (the losers) except one (the winner) on many fibers. Axon-induced AChR aggregates underwent comparable selection of winners and losers. The results suggest that agrin and acetylcholine-driven muscle activity provided by transplanted axons are sufficient to elicit in a denervated adult muscle fiber processes that regulate the size and distribution of ectopic neuromuscular junctions.
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Affiliation(s)
- I Mathiesen
- Department of Physiology, University of Oslo, Norway
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Desaulniers P, Lavoie PA, Gardiner PF. Endurance training increases acetylcholine receptor quantity at neuromuscular junctions of adult rat skeletal muscle. Neuroreport 1998; 9:3549-52. [PMID: 9858357 DOI: 10.1097/00001756-199811160-00001] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The aim of the study was to test the hypothesis that a 16 week endurance training program would alter the abundance of endplate-associated nicotinic acetylcholine receptors (nAChR) in various rat skeletal muscles. We found a 20% increase in endplate-specific [125I]alpha-bungarotoxin binding in several muscles of trained rats, accompanied by equal susceptibility of toxin binding to the inhibitory effect of D-tubocurarine in sedentary and trained muscles. We conclude that the neuromuscular junction adaptations that occur with increased chronic activation include an increase in nAChR number. Results of experiments designed to determine nAChR turnover also suggest that this effect is mediated by an alteration in the receptor's metabolic state. The potential implications and mechanisms of this adaptation are discussed.
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Affiliation(s)
- P Desaulniers
- Département de Kinésiologie, Université de Montréal, Québec, Canada
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Roy RR, Wilson R, Edgerton VR. Architectural and mechanical properties of the rat adductor longus: response to weight-lifting training. Anat Rec (Hoboken) 1997; 247:170-8. [PMID: 9025996 DOI: 10.1002/(sici)1097-0185(199702)247:2<170::aid-ar3>3.0.co;2-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND The primary objective of this study was to determine the effects of an 8 week weight-lifting program on the mechanical, histochemical, and architectural properties of the rat adductor longus muscle, a predominantly slow adductor muscle. METHODS The weight-lifting program was progressive such that the rats were performing three bouts of ten lifts with 300% body weight load every other day during the last 3 weeks of training. The in situ mechanical properties, fiber type composition, and architectural characteristics of the muscle were determined in control and weight-trained rats. Intramuscular electromyographic recordings were used to verify the recruitment of the adductor longus during the lifting task. RESULTS The adductor longus was composed predominantly of slow fibers (approximately 80% slow oxidative) and had a relatively simple architectural design, i.e., one motor end-plate band near the center of the muscle, virtually no angle of pinnation of the fibers from the line of pull, and a fiber length:muscle length ratio of 0.72. The mean fiber type composition and fiber size, the total fiber number, and the mean physiological cross-sectional area of the adductor longus were similar in the two groups of rats. The mean body weight of weight-lifting rats was significantly less than control. The weight of the adductor longus relative to body weight and its fatigue resistance were higher and the maximum rate of shortening was slower in weight-lifting than in control rats. No other mechanical property was significantly affected by the training program. CONCLUSIONS The results indicate that approximately 1 minute of over-load every other day by physiological recruitment of motor units can induce remodeling of the adductor longus of growing rats; i.e., the trained muscles were slower and less fatigable than control. Given that the effects on the architectural or force-generating properties of the muscles were small, the marked improvement in the ability to lift heavier loads as the training progressed appears to be more attributable to neurally related than to muscle-related phenomena.
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Affiliation(s)
- R R Roy
- Brain Research Institute, University of California, Los Angeles 90095-1761, USA
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Pasino E, Buffelli M, Arancio O, Busetto G, Salviati A, Cangiano A. Effects of long-term conduction block on membrane properties of reinnervated and normally innervated rat skeletal muscle. J Physiol 1996; 497 ( Pt 2):457-72. [PMID: 8961187 PMCID: PMC1160996 DOI: 10.1113/jphysiol.1996.sp021780] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
1. Do motoneurons regulate muscle extrajunctional membrane properties through chemical (trophic) factors in addition to evoked activity? We addressed this question by comparing the effects of denervation and nerve conduction block by tetrodotoxin (TTX) on extrajunctional acetylcholine (ACh) sensitivity and action potential resistance to TTX in adult rats. 2. We applied TTX to sciatic or tibial nerves for up to 5 weeks using an improved blocking technique which completely suppresses conduction but avoids nerve damage. 3. Reinnervation by TTX-blocked axons had no effect on the high ACh sensitivity and TTX resistance induced by nerve crush. 4. Long-lasting block of intact nerves (up to 38 days) induced extrajunctional changes as pronounced as after denervation. At shorter times (3 days), however, denervation induced much larger changes than TTX block; such a difference is thus only transiently present in muscle. 5. The effects of long-lasting block were dose dependent. Dose levels (6.6 micrograms day-1) corresponding to those used in the literature to block the rat sciatic nerve induced muscle effects much smaller than those induced by denervation, confirming published data. Our novel finding is that equal effects are obtained using doses substantially higher (up to 10.5 micrograms day-1). For the soleus it was necessary in addition to apply the TTX directly to the smaller tibial nerve. 6. The TTX-blocked nerves were normal in their histological appearance and capacity to transport anterogradely 3H-labelled proteins, to release ACh in quantal and non-quantal form or cluster ACh receptors and induce functional ectopic junctions on denervated soleus muscles. 7. We conclude that muscle evoked activity is the physiological regulator of extrajunctional membrane properties. Chemical factors from the nerve do not appear to participate in this regulation. The stronger response to denervation at short times only is best accounted for by factors produced by degenerating nerves.
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Affiliation(s)
- E Pasino
- Dipartimento di Scienze Neurologiche e della Visione, University of Verona, Italy
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Abstract
This review highlights various aspects of a number of experimental myological alterations, induced by different chemical toxicants, including anticholinesterase, colchicine, vincristine, chloroquine, tetanus toxin, botulinum toxin, reserpine and emetine. Despite their chemical diversity and mechanism(s) of action, it is evident from the data discussed here that remarkably different toxic agents exert quite similar effects and induce toxic myopathies. The latter include preferential involvement of slow-twitch red muscle, mitochondrial derangement, denervation-like alterations, formation of membranous whorls, tubular aggregates, autophagic vacuoles and axonal sprouts. The non-invasive experimental models discussed here are valuable in studying various aspects of myopathology in the absence of any mechanical damage to the innervating elements from neurons to axonal terminals.
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Affiliation(s)
- M A Khan
- Department of Anatomy and Cell Biology, State University of New York, Brooklyn 11203, USA
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Balice-Gordon RJ, Thompson WJ. The organization and development of compartmentalized innervation in rat extensor digitorum longus muscle. J Physiol 1988; 398:211-31. [PMID: 3392671 PMCID: PMC1191769 DOI: 10.1113/jphysiol.1988.sp017039] [Citation(s) in RCA: 68] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
1. We have examined the innervation of the rat extensor digitorum longus (EDL) muscle by the two extramuscular branches formed from the bifurcation of its muscle nerve. Observations of muscle contractions, recordings of end-plate potentials, and glycogen depletion of young adult muscles show that each branch innervates a separate region or 'compartment' in the muscle. The branch entering the muscle nearer the knee (the K branch) innervates fibres in the anteromedial half of the muscle whereas the branch entering closer to the foot (the F branch) innervates fibres located posterolaterally. Individual EDL motoneurones project either into the K or the F branch and therefore innervate fibres located in one compartment. The boundary between the compartments is usually sharply delineated. No obvious anatomical feature exists within the muscle which would explain the division of the muscle into two distinct regions. 2. The presence of a segmentotopic projection from the spinal cord to the muscle was investigated to evaluate its possible contribution to the compartmental pattern. The most posterior neurones of the EDL motor pool were found to project more frequently to the posterolateral F compartment; similarly, the most anterior neurones most frequently project to the anteromedial K compartment. However, each compartment is innervated by both anteriorly and posteriorly located motoneurones. The segmentotopic projection is too weak to explain the presence of neuromuscular compartments. 3. The post-natal period of synapse elimination appears to play at best a minor role in setting up the compartmentalized innervation. Glycogen depletion and intracellular recording in 1-2-day-old muscles show that each nerve branch innervates fibres in the same region of the muscle as in the adult. Most of the fibres in each compartment are polyneuronally innervated by axons in their own particular nerve branch, although fibres located near the boundary between the two compartments are innervated by axons from both nerve branches. This convergent innervation from the two branches disappears in concert with the elimination of polyneuronal innervation throughout the muscle. A random elimination of these convergent inputs appears adequate to explain the final compartmental pattern. 4. Our findings suggest that the compartmental pattern is primarily the consequence of te segregation of EDL motoneurones into two nerve branches which are directed into separate regions of the muscle.
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Hennig R. Late reinnervation of the rat soleus muscle is differentially suppressed by chronic stimulation and by ectopic innervation. ACTA PHYSIOLOGICA SCANDINAVICA 1987; 130:153-60. [PMID: 3591386 DOI: 10.1111/j.1748-1716.1987.tb08121.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Soleus (SOL) and extensor digitorum longus (EDL) muscles in adult rats were kept denervated for 2 months by four repeated freezes at 2-week intervals of the sciatic nerve. Reinnervation was studied in the absence or presence of chronic muscle stimulation, starting 1 month before reinnervation began. In addition, reinnervation was studied in SOL muscles where a previously transplanted fibular (FIB) nerve had formed ectopic neuromuscular junctions outside the original endplate area. After repeated freezes only, reinnervation was complete judged by tension measurements and histochemical examinations in SOL (n = 7) and EDL (n = 8) muscles. In directly stimulated muscles reinnervation was incomplete, and the force tensions evoked from indirect stimulation was on average 87 (n = 5) and 82% (n = 5) of direct muscle stimulation in SOL and EDL muscles, respectively. Of ectopically innervated SOL muscle fibres, only 26% became reinnervated in 12 muscles. Denervation and reinnervation increased the number of muscle fibres in stimulated (n = 4) and unstimulated (n = 5) EDL muscles by 18 and 15%, respectively. In stimulated (n = 4) and unstimulated (n = 7) SOL muscles, on the other hand, the number of muscle fibres remained normal. The stronger suppression of reinnervation in ectopically reinnervated compared to chronically stimulated SOL fibres indicates that reinnervation can also be suppressed by activity independent influences from the foreign nerve.
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Fedorov VV. Postsynaptic currents in phasic and tonic muscle fibers of the rat extraocular muscle. NEUROPHYSIOLOGY+ 1987. [DOI: 10.1007/bf01056003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Cangiano A, Magherini PC, Pasino E, Pellegrino M, Risaliti R. Interaction of inactivity and nerve breakdown products in the origin of acute denervation changes in rat skeletal muscle. J Physiol 1984; 355:345-65. [PMID: 6491995 PMCID: PMC1193495 DOI: 10.1113/jphysiol.1984.sp015423] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The action of nerve breakdown products on innervated fibres of soleus and extensor digitorum longus muscles was investigated with the following procedures: partial denervation, sensory or sympathetic denervation, section of a previously transplanted foreign nerve. Each procedure was performed either in isolation or combined with chronic muscle inactivity obtained by blocking impulse conduction along the sciatic nerve. Silastic cuffs containing tetrodotoxin (TTX) and sodium chloride were utilized for the block. Partial denervation induced extrajunctional sensitivity to acetylcholine (ACh) and resistance to tetrodotoxin not only in the denervated but also in the innervated fibres. The effects in the innervated fibres were equal in magnitude to those in the denervated fibres, provided they were paralysed. The onset of the membrane changes was synchronous in the two classes of fibres and their amount correlated with the extent of partial denervation. If the innervated fibres were normally active, the membrane changes were still detectable, but considerably smaller than in the denervated fibres. Sensory denervation (removal of dorsal root ganglia L4 and L5) was followed by the development of moderate ACh supersensitivity and TTX resistance in chronically paralysed muscles. Furthermore, section of radicular nerves (total denervation, i.e. efferent plus afferent) induced larger membrane changes than those observed following section of ventral roots alone (efferent denervation). Sympathetic denervation was ineffective even when associated with chronic muscle paralysis. Section of a previously transplanted mixed nerve (superficial fibular) was ineffective if the soleus muscle was normally active, while it induced marked extrajunctional ACh sensitivity and TTX resistance when combined with chronic paralysis of the muscle. Section of a transplanted sensory nerve (sural) also induced extrajunctional membrane changes in paralysed soleus muscles, but their magnitude was much smaller than after section of mixed nerves. We conclude that products of nerve destruction, especially those of motor axons, induce membrane changes of striking magnitude when potentiated by muscle inactivity. Such an action may also explain the greater efficacy of denervation vs. pure inactivity, at least at early times after their onset.
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Brenner HR, Meier T, Widmer B. Early action of nerve determines motor endplate differentiation in rat muscle. Nature 1983; 305:536-7. [PMID: 6621701 DOI: 10.1038/305536a0] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The formation of a motor endplate is characterized by a complex series of changes in the properties of the subsynaptic acetylcholine receptors (AChRs). Among the last changes to occur are the shortening of the apparent mean open time of their ion channels from about 4 to 1 ms and an increase in the single-channel conductance. This conversion of channel gating at the endplate seems to be induced by the motor neurone. We report here that fast channel gating also develops at nerve-free endplate sites of fibres that had been denervated while gating was still slow. At such sites, junctional folds will develop in the absence of the nerve terminal. Although the conversion of channel gating and the formation of junctional folds are late events in endplate development, the neural signals inducing these changes must therefore act at the earliest stages of junctional development.
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Taxt T. Local and systemic effects of tetrodotoxin on the formation and elimination of synapses in reinnervated adult rat muscle. J Physiol 1983; 340:175-94. [PMID: 6887046 PMCID: PMC1199204 DOI: 10.1113/jphysiol.1983.sp014757] [Citation(s) in RCA: 38] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
1. Polyneuronal innervation of normal and reinnervated fourth deep lumbrical muscle fibres was studied with tension measurements and intracellular recordings. From the tenth day after a complete crush of the muscle nerve, some of the reinnervated muscles were completely paralysed for up to 15 days by local application of tetrodotoxin (TTX) to the sciatic nerve. Other animals received only systemic infusion of TTX during the muscle reinnervation.2. Measurements of tetanic-tension overlap suggested that about 6% of the muscle fibres in the normal lumbrical muscle were polyneuronally innervated, while intracellular recordings suggested that the percentage was as high as 25%. This discrepancy was mainly due to the presence of one small, sub-threshold end-plate potential (e.p.p.) and one large, suprathreshold e.p.p. in almost all polyneuronally innervated muscle fibres.3. Intracellular recordings during muscle reinnervation showed that the extent of polyneuronal innervation reached a maximum of 50% 10-15 days after denervation and that by 16-20 days this had decreased to a level similar to that found in normal muscle.4. After a week of total muscle paralysis the extent of polyneuronal innervation had increased to about 80%, estimated by both tension measurements and intracellular recordings. Subsequently, there was no sign of any net elimination of the polyneuronal innervation, even in muscles paralysed for up to two weeks. Many of the polyneuronally innervated fibres were innervated by at least two motor axons. each producing suprathreshold e.p.p.s.5. In muscles contralateral to the paralysed muscles, the extent of polyneuronal innervation reached a maximum of 50% 10-15 days after denervation as in reinnervated muscles not exposed to TTX. But in contrast to the subsequent decrease in the extent of polyneuronal innervation in animals which received no TTX, this level of polyneuronal innervation persisted in muscles contralateral to the paralysed muscles. The same was true for reinnervated muscles in animals which only received TTX systemically.6. The increased level of polyneuronal innervation after TTX application was not caused by differences in the number of motor units or in number of muscle fibres.7. Paralysed muscles relaxed much more slowly than non-paralysed muscles at the end of a fused tetanic contraction. The tetanus/twitch ratio of these muscles was also smaller than in contralateral control muscles and the rise time of the twitch was greater.8. It is concluded that a substantial fraction of the fibres in the normal lumbrical muscle of young rats is polyneuronally innervated. After reinnervation, the normal innervation pattern is re-established, but no net elimination of the polyneuronal innervation occurs unless either nerve or muscle or both are active. A net elimination of synapses is also prevented when TTX is present systemically in low concentrations.
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Taxt T. Cross-innervation of fast and slow-twitch muscles by motor axons of the sural nerve in the mouse. ACTA PHYSIOLOGICA SCANDINAVICA 1983; 117:331-41. [PMID: 6192680 DOI: 10.1111/j.1748-1716.1983.tb00004.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The extensor digitorum longus (EDL) or soleus muscles of adult mice were cross-innervated by the sural nerve (SN) and deprived of their original innervation. The number and sizes of motor units and the location of endplates in these muscles were studied 1.5 to 16 months later. In the EDL muscle, the SN cross-innervated the original endplates. Very few ectopic endplates were seen, even when the nerve was implanted well outside of the original endplate area. Only 3% of the fibres were polyneuronally innervated. In the soleus muscle, however, the SN formed large numbers of ectopic endplates whether the nerve was implanted in the original endplate zone or outside of it. In addition, 20% of the muscle fibres were polyneuronally innervated. The SN cross-innervated both EDL and soleus muscles completely. There was no preference for a particular group of the SN motoneurones since all the cross-innervated muscles were innervated by all SN motor axons and the motor unit sizes of the SN were similar in the cross-innervated EDL and soleus muscles. It is concluded that intrinsic properties of a muscle determine the ability to form ectopic synapses. The distribution of the motor unit sizes is determined by the particular pool of motoneurones which innervates the muscle.
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Gardiner PF, Lapointe M, Gravel D. Exercise effects on recovery of muscle acetylcholinesterase from reduced neuromuscular activity. Muscle Nerve 1982; 5:363-8. [PMID: 6289098 DOI: 10.1002/mus.880050505] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
In order to investigate the effects of reduced and subsequently increased neuromuscular activity on muscle acetylcholinesterase (AChE), rats had one hindlimb immobilized with plaster casts for 4 weeks and were killed either at the end of immobilization (group I), after 4 weeks of resumed normal activity following cast removal (group R), or after 4 weeks of resumed activity supplemented with a daily treadmill-walking task (group E). Immobilization resulted in a decrease in adductor longus muscle weight to 66.4% of control; total muscle end-plate-associated AChE was decreased to 51.4%. Total muscle ACh hydrolysis was not significantly affected. Mild daily exercise during recovery increased total muscle end-plate AChE to control levels after 4 weeks, while in group R the corresponding level was significantly lower (84.4%). Decreased neuromuscular activity has different effects on end-plate AChE and non-end-plate AChE. Mild endurance-type overload during recovery from immobilization can accelerate recovery of end-plate AChE activity to normal.
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Kucera J. Comparison of motor endings of the cat's muscle spindle stained for NADH-tetrazolium reductase and cholinesterase. HISTOCHEMISTRY 1982; 74:95-106. [PMID: 7085353 DOI: 10.1007/bf00495055] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Cat muscle spindles were examined histochemically in serial transverse sections of tenuissimus muscles stained for ATPase, NADH-TR and ChE alternating sequentially. Motor nerve terminals on nuclear bag1, bag2 and nuclear chain intrafusal muscle fibers were identified in periodic sections stained for ChE. Intrafusal fiber regions that carried ChE-active areas were then examined in staining for NADH-TR. The motor endings on the three types of intrafusal fiber differed in their apparent histochemical content of both ChE and NADH-TR. The observations suggest that functional differences may exist among motor nerve terminals on the various intrafusal fiber types.
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Pockett S. Elimination of polyneuronal innervation in proximal and distal leg muscles of chick embryos. Brain Res 1981; 227:299-302. [PMID: 7225896 DOI: 10.1016/0165-3806(81)90117-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
In chick embryo leg muscles, elimination of polyneuronal innervation takes place one to 1.5 days earlier in the thigh muscle m. ambiens than in the foot muscle m. flexor hallucis brevis. Initial formation of synapses takes place 2-3 days earlier in the proximal than the distal muscle, so the length of time synapses have been active may be a factor in the control of elimination of polyneuronal innervation during development.
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Cangiano A, Lømo T, Lutzemberger L, Sveen O. Effects of chronic nerve conduction block on formation of neuromuscular junctions and junctional AChE in the rat. ACTA PHYSIOLOGICA SCANDINAVICA 1980; 109:283-96. [PMID: 7446172 DOI: 10.1111/j.1748-1716.1980.tb06599.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The development of ectopic n.m.j.s. between the transplanted superficial fibular nerve and the soleus muscle has been studied in adult rats. Impulse conduction in the sciatic nerve was blocked chronically and synapse formation between the blocked fibular nerve and the paralysed soleus was compared with synapse formation between non-blocked fibular nerves and denervated soleus muscles. Nerves with conduction block readily made new n.m.j.s. Thus 6 and 10--14 days after the onset of the block the number of newly innervated muscle fibres, the percentage of innervated fibres responding with action potentials and the frequency of m.e.p.p.s. at new junctions were comparable to that observed during innervation by non-blocked nerves. Muscle fibres innervated by both the original soleus nerve and the foreign fibular nerve were regularly encountered in the impulse blocked preparations. Junctions formed by impulse blocked fibular nerves had either no or very little AChE activity 10--15 days after the onset of the block. The evidence for this was 1) weak staining for CHE; 2) prolonged rise time and 1/2 decay time of m.e.p.p.s; 3) positive correlation between m.e.p.p. amplitude and 1/2 decay time and 4) insensitivity to anticholinesterases. In contrast, junctions formed by non-blocked fibular nerves had strong AChE activity by these criteria at corresponding times. AChE activity at the original soleus endplates was much reduced 10--15 days after the onset of conduction block.
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Lømo T, Slater CR. Acetylcholine sensitivity of developing ectopic nerve-muscle junctions in adult rat soleus muscles. J Physiol 1980; 303:173-89. [PMID: 6253618 PMCID: PMC1282885 DOI: 10.1113/jphysiol.1980.sp013279] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
1. The development of junctional ACh sensitivity has been studied during the formation of ectopic nerve-muscle junctions (n.m.j.s) between the superficial fibular nerve and the denervated soleus muscle of adult rats. 2. When the soleus nerve was cut 2 weeks or more after implanting the fibular nerve, spontaneous m.e.p.p.s and evoked e.p.p.s were first detected in the vicinity of the fibular nerve sprouts 2.5-3 days later. At this time, peaks of local ACh sensitivity greater than the high level of extrajunctional sensitivity induced by denervation were found near the sprouts of the fibular nerve. 3. During the first week of foreign innervation, the extrajunctional sensitivity of the newly innervated muscle fibres fell, but the peaks of sensitivity in the region of the fibular nerve sprouts persisted. Many of these peaks occurred at sites of transmitter release from the fibular nerve terminals. Each innervated fibre had from 1-8 such peaks. 4. When the fibular nerve was cut 2 days or more after cutting the soleus nerve peaks of ACh sensitivity persisted in the region of the degenerated foreign nerve terminals even if the extrajunctional sensitivity was abolished by direct electrical stimulation of the muscle starting soon after cutting the fibular nerve. 5. When the fibular nerve was left intact, more than half of the peaks of sensitivity formed initially in the region of the foreign nerve sprouts had disappeared 2-3 weeks after cutting the soleus nerve. 6. We conclude that during the formation of ectopic n.m.j.s in adult rat muscle the foreign nerve terminals bring about two types of long-lasting change in the distribution and stability of the underlying ACh sensitivity in the muscle fibre membrane; an increase and stabilization of sensitivity at sites of transmitter release which occurs by the time functional transmission at the newly formed n.m.j.s can be detected, and a loss of sensitivity at some of the sites which takes place about 1-2 weeks later.
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Lømo T, Slater CR. Control of junctional acetylcholinesterase by neural and muscular influences in the rat. J Physiol 1980; 303:191-202. [PMID: 6253619 PMCID: PMC1282886 DOI: 10.1113/jphysiol.1980.sp013280] [Citation(s) in RCA: 117] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
1. The development of AChE at ectopic neuromuscular junctions forming between a transplanted foreign nerve (the superficial fibular nerve) and the denervated soleus muscle has been studied in adult rats. 2. Junctional AChE activity began to appear in the vicinity of the fibular nerve sprouts 6-7 days after section of the soleus nerve and 3-4 days after the onset of transmission. 3. No histochemically detectable AChE appeared when the fibular nerve was cut 0-4 days after the soleus nerve had been cut. 4. Direct electrical stimulation of the denervated soleus muscle caused plaques of true AChE, as determined by inhibitor studies, to appear in muscles where the fibular nerve had been cut 2-4 days after the soleus nerve but not in muscles where the two nerves had been cut at the same time. The plaques appeared only in the vicinity of fibular nerve sprouts and coincided with newly formed but stable peaks of ACh sensitivity. Local application of Neostigmine prolonged and increased the depolarising response evoked by pulses of ACh at these sites. 5. In muscles where the fibular nerve was intact the AChE plaques changed gradually over a few weeks from an immature appearance to a mature appearance characteristic of normal end-plates. In stimulated muscles where the fibular nerve had been cut the plaques stained intensely but remained morphologically immature. 6. We conclude (1) that muscle activity is important for the appearance of AChE at developing neuromuscular junctions and (2) that AChE accumulates only at sites on the muscle surface where the nerve fibres have left a 'trace' upon contact with the muscle fibres. These traces form quickly and persist after nerve-muscle interaction of as little as 2 days. The muscle appears as a major source of junctional AChE since stimulation of the muscle induces intense AChE activity in muscles where the nerve has degenerated.
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Abstract
1. The saturable binding of exchange-labelled tritiated saxitoxin (STX) to the extensor digitorum longus (e.d.l.), diaphragm and soleus muscles of adult rats was studied. By measuring STX uptake to small pieces of muscle, the dissociation constant (KD) and binding capacity could be determined for individual muscles. 2. The affinity for STX is very similar in all three muscles, with a KD of 4.3 +/- 0.3, 5.1 +/- 0.5 and 4.9 +/- 0.5 nM (mean +/- S.E. of mean) at 4 degrees C for e.d.l., diaphragm and soleus respectively. The maximum binding capacity, which varies between different muscles, is 52.6 +/- 2.5, 40.3 +/- 4.9 and 23.8 +/- 1.1 f-mole.mg wet wt.-1 respectively. 3. The affinity of e.d.l. for tetrodotoxin (TTX), measured by inhibition of STX binding, is 12.1 +/- 1.4 nM at 4 degrees C. Raising the temperature to 37 degrees C increases the KD for STX to 6.8 +/- 0.8 nM and the KD for TTX to 47.5 +/- 4.5 nM. 4. STX binding is pH dependent; protons compete with STX for the binding site as if there were a titratable acidic group with a pK of 5.5. 5. The binding capacity of the diaphragm is not uniform along the length of the muscle fibres. Binding at the ends of the fibres is only 78% of that in the central region. 6. Denervation of e.d.l. for 7 days causes no change in the affinity for STX. There is a slight reduction in the binding capacity from 54 +/- 5 to 43 +/- 3 f-mole.mg wet wt.-1. There is no change in the diameter of the muscle fibres.
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Bixby JL, van Essen DC. Regional differences in the timing of synapse elimination in skeletal muscles of the neonatal rabbit. Brain Res 1979; 169:275-86. [PMID: 445158 DOI: 10.1016/0006-8993(79)91030-8] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The time course of disappearance of polyneuronal innervation during development was studied electrophysiologically in skeletal muscles of the rabbit. There were differences of up to a week in the estimated time of onset of synapse elimination in various muscles, with a tendency for the process to begin earlier in muscles situated more anteriorly in the body. There were also differences among muscles in the peak rate of synapse loss during maturation, but these differences do not appear to be related to position in the body or to contractile properties of the muscle.
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Abstract
1. The formation of ectopic junctions between the 'foreign' superficial fibular nerve and the soleus muscle of adult rats, and its relation to changes in extrajunctional sensitivity to acetylcholine (ACh), has been studied by denervating the muscle 3-6 weeks after implanting the foreign nerve. 2. The earliest signs of nerve-muscle transmission were seen 2.5-3 days after denervation, in those fibres where the extrajunctional ACh sensitivity first reached its full post-denervation level. The number of innervated fibres continued to increase throughout the first week after denervation until 70-100% of fibres underlying the foreign nerve growth were innervated. 3. Direct stimulation of muscles with chronically implanted electrodes from the time of denervation prevents the formation of functional neuromuscular junctions (n.m.j.s). If stimulation begins 2 or 4 days after denervation, some functional n.m.j.s are formed which can be detected 7-9 days after denervation, though not as many as in the absence of stimulation. 4. Direct stimulation of muscles from the time of denervation prevents the development of detectable extrajunctional ACh sensitivity. If stimulation begins 2 days after denervation nearly maximal sensitivity develops during the third day and then rapidly declines to undetectable levels by the beginning of the eight day after denervation.
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Thompson W, Jansen JK. The extent of sprouting of remaining motor units in partly denervated immature and adult rat soleus muscle. Neuroscience 1977; 2:523-35. [PMID: 917280 DOI: 10.1016/0306-4522(77)90049-5] [Citation(s) in RCA: 200] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Crockett JL, Edgerton VR, Max SR, Barnard RJ. The neuromuscular junction in response to endurance training. Exp Neurol 1976; 51:207-15. [PMID: 1261635 DOI: 10.1016/0014-4886(76)90064-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Lomo T, Westgaard RH. Further studies on the control of ACh sensitivity by muscle activity in the rat. J Physiol 1975; 252:603-26. [PMID: 1206569 PMCID: PMC1348486 DOI: 10.1113/jphysiol.1975.sp011161] [Citation(s) in RCA: 198] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
1. Denervated rat soleus muscles were stimulated directly through chronically implanted electrodes and the influence of different amounts and patterns of stimuli on the acetylcholine (ACh) sensitivity of the muscle was studied. The number of stimuli was varied by giving similar trains of stimuli (10 Hz for 10 sec) at different intervals (0 to 12 hr). The pattern of stimulation was varied by giving different trains of stimuli (100 Hz for 1 sec, 10 Hz for 10 sec and 1 Hz continuously) as the same average frequency of stimulation (1 Hz). 2. Stimulation usually started 5 days after the denervation when ACh hypersensitivity was fully developed. Most stimulation procedures reduced extrajunctional ACh sensitivity to normal or below normal values within 5-21 days, and these levels were maintained on prolonged stimulation. 3. The rate at which ACh hypersensitivity disappeared increased with increasing amount and frequency of stimulation. However, as few as 100 stimuli given every 5-5 hr for 3 weeks caused a tenfold reduction of sensitivity. 4. The stimulation had little or no effect on the ACh sensitivity at the end plate. Along the rest of the fibre the sensitivity was reduced at approximately the same rate except near the tendons where it appeared to fall more slowly in some fibres. 5. The stimulation restored the resting membrane potential of the denervated fibres to normal.
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Frank E, Jansen JK, Lomo T, Westgaard RH. The interaction between foreign and original motor nerves innervating the soleus muscle of rats. J Physiol 1975; 247:725-43. [PMID: 1142305 PMCID: PMC1309495 DOI: 10.1113/jphysiol.1975.sp010954] [Citation(s) in RCA: 131] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
1. The fibular nerve was transplanted on to the soleus muscle of the rats. Interruption of the original soleus nerve then permitted cross-innervation, and subsequently, over a period of weeks, re-innervation by the original nerve. 2. Individual muscle fibres were often innervated by both the original and the foreign nerve. The original and foreign end-plates were located in separate regions of the muscle. There were no indications that the original nerve could displace or repress the foreign innervation. 3. The extent of re-innervation by the original nerve depended upon the method of denervation. A single crush of the nerve was followed by virtually complete re-innervation, even of muscle fibres already innervated by the foreign nerve. When re-innervation was delayed by resection of a segment of the nerve only muscle fibres without foreign nerve innervation were re-innervated. Denervation by a simple nerve cut gave an intermediate result. 4. Re-innervation by the original nerve can take place without measurable extrajunctional sensitivity to ACh. 5. The original end-plate region could retain high and localized sensitivity to ACh for several months despite degeneration of its motor nerve terminal and activity of the muscle fibre. 6. Established foreign end-plates were re-innervated by the foreign nerve on muscle fibres with intact original innervation. 7. The factors controlling synapse formation in skeletal muscles are discussed.
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Salpeter MM, McHenry FA, Feng HH. Myoneural junctions in the extraocular muscles of the mouse. Anat Rec (Hoboken) 1974; 179:201-24. [PMID: 4133495 DOI: 10.1002/ar.1091790205] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Frank E, Jansen JK, Lomo T, Westgaard R. Maintained function of foreign synapses on hyperinnervated skeletal muscle fibres of the rat. Nature 1974; 247:375-6. [PMID: 4817857 DOI: 10.1038/247375a0] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Gandiha A, Lord JA, Marshall IG. Further studies on the site of action of nicotinic blocking drugs. Eur J Pharmacol 1973; 23:211-5. [PMID: 4147440 DOI: 10.1016/0014-2999(73)90058-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Heaton J, Buckley GA, Evans RH. The cholinesterase activity of myoneural junctions from frog twitch and tonic muscles. EXPERIENTIA 1972; 28:503-4. [PMID: 5040789 DOI: 10.1007/bf01931842] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Buckley GA, Heaton J. Cholinesterase activity of myoneural junctions from twitch and tonic muscles on the domestic fowl. NATURE: NEW BIOLOGY 1971; 231:154-5. [PMID: 5283018 DOI: 10.1038/newbio231154a0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Metcalfe JC, Metcalfe SM. Metabolic inhibition in primary cell cultures by lipid-soluble molecules. Br J Pharmacol 1970; 40:537P-538P. [PMID: 5497804 PMCID: PMC1703146 DOI: 10.1111/j.1476-5381.1970.tb10640.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
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Buckley GA, Heaton J. Simultaneous determination of choline acetylase and cholinesterase activity. Br J Pharmacol 1970; 40:591P-592P. [PMID: 5497843 PMCID: PMC1703132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
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Namba T, Grob D. Cholinesterase activity of motor end plate in human skeletal muscle. J Clin Invest 1970; 49:936-42. [PMID: 4191769 PMCID: PMC535766 DOI: 10.1172/jci106313] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The activity and properties of cholinesterase of the motor end plate in human intercostal muscle were studied in the isolated muscle membrane. This preparation was used because cholinesterase activity of the membrane preparation was localized in the motor end plate without contamination of cholinesterase of other muscle components. Under the experimental conditions, cholinesterase in a human end plate hydrolyzed 1.21 x 10(8) molecules of acetylcholine per msec, which is smaller than hydrolysis of 2.69 x 10(8) by a motor end plate of rat intercostal muscle. Studies with cholinesterase inhibitors and specific substrates indicated that about 90% of cholinesterase of human motor endplates is acetylcholinesterase, and about 10% is pseudocholinesterase. The end plate cholinesterase had an optimal pH of 7.8 and a Michaelis-Menten constant of 4.15 mmoles/liter, and was stable at 4 degrees C for at least 4 wk. Motor end plates were estimated to contain only about 2% of the total cholinesterase activity of human intercostal muscle, compared with about 20% in rat tibialis anterior muscle. The difference is due to the lower cholinesterase activity of the motor end plate and higher cholinesterase activity of non-end plate components in human muscle than in rat muscle. The isolated muscle membrane provides a useful preparation for the study of the properties of motor end plate in human skeletal muscle.
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Buckley GA, Heaton J. Cholinesterase in endplates of rat and chick: relationship of activity to log-dose response curves and the effects of some inhibitors. Br J Pharmacol 1970; 38:434P-435P. [PMID: 5417864 PMCID: PMC1702823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
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Natoff IL, Reiff B. Differential antagonism of the acutely lethal effects of organophosphates in rats. Br J Pharmacol 1970; 38:433P-434P. [PMID: 5417863 PMCID: PMC1702818 DOI: 10.1111/j.1476-5381.1970.tb08530.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
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Gaze RM, Keating MJ, Straznicky K. The re-establishment of retinotectal projections after uncrossing the optic chiasma in Xenopus laevis with one compound eye. J Physiol 1970; 207:51P-52P. [PMID: 5511133 PMCID: PMC1348641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
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Buckley GA, Heaton J. Decrease in cholinesterase activity of single motor end-plates after thiocholine staining. Br J Pharmacol 1969; 35:P370-1. [PMID: 4180115 PMCID: PMC1703213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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Bennett A, Fleshler B. Action of prostaglandin E 1 on the longitudinal muscle of the guinea-pig isolated colon. Br J Pharmacol 1969; 35:P351-2. [PMID: 5774054 PMCID: PMC1703233 DOI: 10.1111/j.1476-5381.1969.tb07995.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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