Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.6.99.1 (NADPH-diaphorase)
 3,903 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nitric oxide synthase I (NOS I) has been localized to the skeletal muscle sarcolemma in a variety of vertebrate species including man. It is particularly enriched at neuromuscular junctions. Recently, the N-methyl-D-aspartate (NMDA) receptor subunit 1 (NMDAR-1) has been detected in the postjunctional sarcolemma of rat diaphragm, providing a clue as to the possible source of Ca2+ ions that are necessary for NOS I activation. To address this possibility, we studied the distribution of NMDAR-1 and NOS I in mouse and rat skeletal muscles by immunohistochemistry and enzyme histochemistry. NMDAR-1 and NOS I were closely associated at neuromuscular junctions primarily of type II muscle fibers. NOS I was also present in the extrajunctional sarcolemma of this fiber type. Dystrophin, beta-dystroglycan, alpha-sarcoglycan, and spectrin were found normally expressed in both the junctional and extrajunctional sarcolemma of both fiber types. By contrast, in the muscle sarcolemma of MDX mice, dystrophin and dystrophin-associated proteins were reduced or absent. NOS I immunoreactivity was lost from the extrajunctional sarcolemma and barely detectable in the junctional sarcolemma. NOS I activity was clearly demonstrable in the junctional sarcolemma by NADPH diaphorase histochemistry, especially when the two-step method was used. NMDAR-1 was not altered. These data suggest that different mechanisms act to attach NOS I to the junctional versus extrajunctional sarcolemma. It may further be postulated that NMDA receptors are involved not only in the regulation but also sarcolemmal targeting of NOS I at neuromuscular junctions of type II fibers. The evidence that glutamate may function as a messenger molecule at vertebrate neuromuscular junction is discussed.
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PMID:Co-localization of nitric oxide synthase I (NOS I) and NMDA receptor subunit 1 (NMDAR-1) at the neuromuscular junction in rat and mouse skeletal muscle. 939 43

As intrafusal nuclear bag and chain fibers of muscle spindles take part in both sensory and motor functions, these stretch receptors may represent a useful model to answer the question whether nitric oxide (NO) signalling is involved in sensory and motor functions or motor events only, as has already been shown for ordinary extrafusal fibers. To answer these questions, we have applied immunohistochemical and enzyme histochemical methods to serial transverse sections of the rat gastrosoleus muscle for determining the presence or absence of NOS I, NOS-associated diaphorase (NOSaD), AChE and proteins related to the dystrophin complex. NOS I, NOSaD, and AChE were practically absent from the equatorial (central) region of intrafusal fibers, i.e. the site of termination of the primary and secondary afferents. These regions showed weak staining for dystrophin, beta-dystroglycan as well as alpha- and gamma-sarcoglycan. By contrast, all of these molecules were found enriched in the polar (peripheral) regions of the intrafusal fiber sarcolemma. NOS I, NOSaD, dystrophin, beta-dystroglycan and the two sarcoglycans showed a general presence in the sarcolemma, whereas AChE was limited to the endplate region and other circumscribed areas. From these observations we would like to conclude that NO does not appear to be significantly or even not involved in signal transfer to the sensory nerve endings in the intrafusal fibers.
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PMID:NO is not substantially involved in afferent signalling in rat muscle spindles. 942 3

The neuronal isoform of nitric oxide synthase (nNOS, termed also NOS-I) is expressed in normal adult skeletal muscle, suggesting important functions for NO in muscle biology. However, the expression and subcellular localization of NOS in muscle development and myoblast differentiation are largely unknown. In the present study, NOS was immunolocalized with isoform-specific antibodies in developing muscle and in differentiated myoblast cultures (mouse C2C12) together with histochemical NADPH-dependent diaphorase activity that is blocked by specific NOS inhibitors and therefore designated as NOS-associated diaphorase activity (NOSaD). Western blot analysis revealed immunoreactive bands for NOS-I-III in lysates from perinatal and adult muscle tissue and C2C12-myotubes that comigrated with prototypical proteins. In embryonic skeletal muscle, but not in adult myofibers, diffuse cytosolic staining and lack of sarcolemmal NOSaD activity and NOS-I immunoreaction were evident. In both myoblasts and fusioned myotubes, NOSaD and NOS isoforms I-III colocalize in the cytosol. Additionally, members of the sarcolemmal dystrophin-glycoprotein complex (i.e., dystrophin, adhalin, beta1-dystroglycan) immunolocalize in the cytosol of differentiating myoblasts, whereas anti-dystrophin and anti-beta1-dystroglycan clearly delineate the sarcolemma in myotubes. Thus, expression of NOS isoforms I-III and NOSaD is cytosolic in fusion-competent myoblasts during myotube formation in vitro. Interaction of NOSaD/NOS-I with the sarcolemmal dystrophin-complex known from mature myofibers is apparently lacking in prenatal muscle development and differentiating myoblasts. Localization of NOS isoforms thus characterized in myogenic cultures may help further to investigate regulated NO formation in muscle cells in vitro.
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PMID:Nitric oxide synthase (NOS) in mouse skeletal muscle development and differentiated myoblasts. 956 Apr 72

NADPH diaphorase histochemistry and NOS-1 immunohistochemistry on 60 microm thick frozen sections of rat extensor digitorum longus muscles led to the detection of prominent rings clearly encompassing the surface of the muscle fibres. These so far unknown costameres were usually found as doublets flanking a space of about 2 microm width. Because these costameric doublets did not appear in regular periods, we designate them irregular costameres to discriminate them from regular ones with a 1 microm periodicity overlying Z-discs and M-lines. Irregular costameres were thicker than the regular ones and free of intercostameres. Immunohistochemistry demonstrated that NOS-1 was co-localized with integral (beta-dystroglycan, alpha-sarcoglycan) and peripheral (caveolin-3, dystrophin) members of the enlarged dystrophin complex in the irregular costameres but not with non-sarcolemmal organized proteins (myosin heavy chain, alpha-actinin, desmin and sarcoplasmic reticulum-located Ca2+-dependent ATPase-1). Invaginations of the sarcolemma to form irregular costameres were observed. In teased myofibres the sarcolemma between two following irregular costameres was ballooned, while the irregular costameres themselves clamped the fibres together. Finally, the number of detectable irregular costameres was significantly increased in maximally contracted extensor digitorum longus muscles generated by electric stimulation but decreased in mechanically stretched ones. Combining these observations, we hypothesize that irregular costameres belong to a reserve zone for the sarcolemma necessary for the contraction/relaxation cycle in myofibres.
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PMID:Irregular costameres represent nitric oxide synthase-1-positive sarcolemma invaginations enriched in contracted skeletal muscle fibres. 1125 90