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M H Ellisman

Publications and source records attributed to M H Ellisman.

At least 127 records · Page 7Linked to original sources
PubMed1987

Distribution of (Na+ + K+)ATPase and sodium channels in skeletal muscle and electroplax.

The distributions of (Na+ + K+)ATPase and sodium channels in skeletal muscle fibres and electrocytes were determined by immunofluorescent and immunoelectron microscopic techniques using antibodies against rat and eel (Na+ + K+)ATPase and the eel electric organ sodium channel. The extrajunctional sarcolemma of skeletal muscle was uniformly stained by polyclonal antibodies against (Na+ + K+)ATPase and the sodium channel. The T-tubule system of skeletal muscle was also labelled heavily for both (Na+ + K+)ATPase and the sodium channel. The terminal cisternae of the sarcoplasmic reticulum was stained for (Na+ + K+)ATPase but not sodium channels. At the motor endplate, (Na+ + K+)ATPase-like immunoreactivity was present along the plasmalemma of motor nerve terminals but not along the postsynaptic junctional sarcolemma. Paradoxically, a monoclonal antibody that binds to the alpha form of the catalytic subunit of (Na+ + K+)ATPase from rat hepatocytes and renal tubule cells did not label the enzyme in rat skeletal muscle. In electrocytes, (Na+ + K+)ATPase-like immunoreactivity was concentrated primarily along the plasmalemma and calveolae of the non-innervated face. In contrast, sodium channel-like immunoreactivity was concentrated along the plasmalemma of the innervated face except in the clefts of the postsynaptic membrane. Thus, we conclude that at endplates both the (Na+ + K+)ATPase of rat skeletal muscle and sodium channels of eel electrocytes are not concentrated in the juxtaneuronal postsynaptic membrane. We also interpret the failure of the monoclonal anti-alpha (Na+ + K+)ATPase antibodies to bind to the enzyme in muscle to indicate that the catalytic subunit of skeletal muscle (Na+ + K+)ATPase displays different epitopes than does the alpha subunit of kidney and liver.

Animals↗
PubMed1987

The distribution of (Na+ + K+)ATPase is continuous along the axolemma of unensheathed axons from spinal roots of 'dystrophic' mice.

(Na+ + K+)ATPase-like immunoreactivity along the axolemma of sensory and motor neurons and the plasmalemma of Schwann cells from spinal roots of dystrophic mice (129 ReJ Dy/Dy) was determined using polyclonal antibodies specific for guinea pig renal (Na+ + K+)ATPase (GP-17), along with polyclonal (439-2) and monoclonal (9A5) antibodies specific for rat renal (Na+ + K+)ATPase. In normal and dystrophic mice, (Na+ + K+)ATPase-like immunoreactivity was observed along the axolemma at nodes of Ranvier using GP-17 and 439-2, each of which binds to isozymes of (Na+ + K+)ATPase composed of the alpha and alpha + forms of the catalytic subunit. Staining was not seen along the nodal axolemma with 9A5, a preparation that binds to the alpha form of the catalytic subunit. The terminal processes and microvilli of Schwann cells were stained using all three antibody probes. The axolemma of unensheathed axons in dystrophic mice was continuously and uniformly labelled with GP-17 and 439-2, but not 9A5. Concentrations of (Na+ + K+)ATPase-like immunoreactivity along Schwann cell processes were observed most often in areas adjacent to unensheathed axolemma. At heminodes, staining abruptly decreased along Schwann cell processes in areas that were separated from the unensheathed axolemma by other intervening Schwann cell processes. It was concluded from these data that in dystrophic mice (Na+ + K+)ATPase is uniformly distributed along unensheathed portions of axons without evidence of detectable focal concentrations of the enzyme, and that the catalytic subunit of (Na+ + K+)ATPase along unensheathed axons is distinct from the alpha form found in Schwann cells and other organs. In addition, (Na+ + K+)ATPase is concentrated along the plasmalemma of Schwann cells in regions of close apposition to axolemmal areas associated with large ionic fluxes.

Animals↗
PubMed1987

Diagnostic levels of ultrasound may disrupt myelination.

Neonatal rats 3 to 5 days of age were exposed to the ultrasound beam from a medical ultrasound imaging system. Dorsal nerve roots were examined by electron microscopy. Comparison between exposed and sham-exposed controls revealed disruption of the nodes of Ranvier attributable to ultrasound. Morphologic changes ranged from vacuole formation in the paranodal region to frank demyelination and were still evident after 24 h of recovery. Rats of this age are at a stage of myelination similar to that of a human fetus 4 to 5 months. The ultrasound intensities used in this study are consistent with those used for human imaging (SPTA 0.135 mW/cm2, SATA 0.045 mW/cm2, SPTP 8.7 W/cm2, SPPA 1.9 W/cm2), but the relevance of these findings to clinical ultrasound will require further study.

Animals↗
PubMed1986

Axons regenerated through silicone tube splices. I. Conduction properties.

Changes in conduction properties of axons regenerating across a 10-mm gap bridged by a silicone cuff were investigated from compound action potential responses. Compound action potentials were detected as early as 6 weeks after surgery, and were small and slowly conducted at maximum velocities of about 3 m/s. With longer regeneration time, the potentials increased in size, velocity, and complexity. Conduction velocities increased rapidly at first than slowly and asymptotically approached rates that were approximately 40% below normal after 10 months. One component of the compound action potential, the refractory period, decreased from 5 ms to near normal value after only 3 months. The time constant of excitation changed more rapidly, and after 2 months approximated values near those for controls. The properties of axons regenerated across an epineural suture with no gaps. The database for the time course of events established here will be useful in guiding studies using the silicone cuff technique as an in situ experimental chamber for studies of regeneration and remyelination.

Animals↗
PubMed1986

Axons regenerated through silicone tube splices. II. Functional morphology.

The recovery of axons regenerated through silicone tube splices was studied with electron microscopic and morphometric methods. Regenerated nerves contained both myelinated and unmyelinated axons of near normal morphology. The number and diameter of axons increased with postoperative time, and size-frequency histograms demonstrated that regeneration occurred in all major fiber groups. Remyelination occurred between about 4 and 6 weeks. Some of the smallest regenerated axons had unusually thick myelin sheaths, but overall regenerated axons had a slightly thinner sheath compared with similar-size normal fibers, although the ratio of sheath thickness to axon size was within the normal limits of g = 0.65 to 0.8 by 6 weeks. Axons did not, however, regain their normal size within 10 months of surgery. This deficit was apparently the primary factor limiting conduction velocity in these regenerated axons.

Animals↗
PubMed1986

Alterations in the ultrastructure of peripheral nodes of Ranvier associated with repetitive action potential propagation.

We have studied the structure of the node of Ranvier following physiological activation and electrophysiological monitoring. Our results indicate that some structures within the nodal complex undergo microanatomic alterations concomitant with repetitive impulse propagation. The experiments were designed to determine the nature and extent of the morphologic changes and any associated changes in the compound action potential. Frog dorsal roots were examined by thin-section electron microscopy after having been either implanted, but not stimulated ("0 Hz control"), or orthodromically activated for 15 min at frequencies of 2, 5, 20, or 50 Hz. Roots were either fixed immediately and processed for electron microscopy or were allowed to recover for periods of 15, 30, or 45 min prior to fixation. A change in nodal structure was found that correlates with the different stimulation regimens. Specifically, there was an increase in the size and number of (extracellular) paranodal intramyelinic vacuoles after stimulation at 20 or 50 Hz when compared both to the implanted nonstimulated controls and to fibers stimulated at low frequency (2 or 5 Hz). This morphologic change occurs in the vicinity of the nodal complex without similar alterations in the morphology of the internodal regions or changes in the dimensions of the nodal gap. This form of microanatomic changes is reversible and is not seen if stimulation is halted and the fiber bundle allowed to recover in Ringer's prior to processing for morphologic evaluation. Changes in the compound action potential (CAP) parallel this structural alteration. The CAP is seen to slow and decrease in amplitude through the 15 min stimulation phase and then to regain its velocity and amplitude during the recovery. When TTX was applied to the preparation during stimulation the CAP was abolished and changes in the paranodal structure were not observed. Structure-function relationships indicated by these results are discussed in the context of several dynamic aspects of nodal physiology.

Action Potentials↗
PubMed1985

Synaptic morphology and differences in sensitivity.

A relation between synaptic morphology and physiology was observed in an in vitro preparation of a sense organ (the ampulla of Lorenzini), in which activity was monitored from the primary afferent neurons before electron microscopic examination of the afferent synapses. The depth of the postsynaptic trough decreased as prefixation sensitivity of the sense organ decreased. This relation and other ultrastructural differences suggest that physiological properties of synapses are influenced by morphological features. Thus, synapses might be morphologically dynamic to modulate synaptic efficacy in relatively long-term phenomena.

Animals↗
PubMed1985

Localization of sodium/potassium adenosine triphosphatase in multiple cell types of the murine nervous system with antibodies raised against the enzyme from kidney.

This report describes the development and characterization of a battery of highly specific antibodies to sodium/potassium (Na+ + K+)-ATPase and their use in localizing this enzyme in nervous tissue. The immunolabeling characteristics of polyclonal antibodies and monoclonal antibodies (Schenk, D. B., and H. L. Leffert (1983) Proc. Natl. Acad. Sci. U. S. A. 80: 5281-5285) raised against rat renal (Na+ + K+)-ATPase were compared. The interspecies cross-reactivity of the polyclonal anti-rat antibodies was examined by determining their binding to purified rat, eel, or dog enzyme. The immunostaining characteristics of the IgG fraction of the polyclonal antibody preparations, their affinity-purified derivatives, and the monoclonal antibodies were compared. The results obtained with each of these were similar, providing information about where focal concentrations of the enzyme exist within nervous tissue. The IgG fraction of the polyclonal antibody preparations provided the most sensitive probe, facilitating localization of the (Na+ + K+)-ATPase in the tissue sections from various regions of the nervous system. (Na+ + K+)-ATPase-like immunoreactivity was observed along the plasmalemma of alpha-motor neurons and at the nodal axolemma of myelinated axons from the central or peripheral nervous system. It was determined that the absence of labeling for the enzyme along the paranodal or internodal regions of the axolemma was not an artifact due to a limited accessibility of antibody to these regions. Some central nervous system glial cells demonstrated abundant amounts of plasmalemmal and intracellular (Na+ + K+)-ATPase-like immunoreactivity. These cells were identified as astroglia by positive labeling of cells in serial sections for glial fibrillary acid protein immunoreactivity in the soma and radial processes in optic nerve, or velous processes in the cerebellum. Astrocyte processes overlying the nodal axolemma also stained positively for the enzyme. (Na+ + K+)-ATPase-like immunoreactivity was not observed in association with oligodendroglia cell bodies or their processes forming myelin sheaths. In contrast, the plasmalemma of myelinating Schwann cells showed greatest immunoreactivity in the region of the node of Ranvier. Although a focal concentration of immunoreactivity was observed along node- and paranode-associated regions of Schwann cells, a lower level of uniform staining was noted along the entire Schwann cell surface membrane.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1985

The neuronal endomembrane system. I. Direct links between rough endoplasmic reticulum and the cis element of the Golgi apparatus.

This is the first of three papers describing new components and structural relationships within the neuronal endomembrane system. This system includes: the nuclear envelope, rough endoplasmic reticulum, the Golgi apparatus, lysosomes, axoplasmic reticulum, and discrete cytoplasmic compartments such as vesicles, multivesicular bodies, and so on. Previous high voltage electron microscope studies of osmium-impregnated Golgi apparatus have shown that small varicose tubules often arise from the cis element. In bullfrog spinal ganglia, these tubules have been seen to extend into cytoplasmic domains occupied by rough endoplasmic reticulum (RER). This study was undertaken to determine whether varicose tubules form direct connections with RER and to measure cytoplasmic density of varicose tubules. Spinal ganglia from Rana catesbeiana were fixed by osmium impregnation and, in some cases, were then stained en bloc with lead aspartate. Sixty- to 3000-nm-thick sections of this tissue, as well as of ganglia prepared by conventional protocol, were studied using standard and high voltage electron microscopy. Quantitative analysis revealed that 9% of the varicose tubules connected with the Golgi cis element. To determine whether continuities existed between RER and any of these tubules, more than 50 tubules were fully reconstructed from images of serial sections. The "ends" of these reconstructed tubules were then studied by high magnification stereoscopy. This was facilitated by the en bloc lead staining which allowed visualization of unimpregnated RER elements along with the impregnated tubules. Small varicose tubules as well as larger smooth tubules were found to have formed confluent bridges between the cis element and RER. In addition, the varicose tubules were found to bridge widely separated elements of RER. Finally, numerous examples of varicose and smooth tubules were seen to extend from RER and from cis elements to eventually form blind endings. These findings raise the possibility that the tubules form highly dynamic transitory connections between RER and the Golgi apparatus as well as between separated elements of RER. Those between RER and Golgi apparatus are ideally positioned to play a major role in the transfer of protein or lipid components first assembled in RER to the Golgi apparatus for terminal synthetic modification.

Animals↗
PubMed1985

The neuronal endomembrane system. III. The origins of the axoplasmic reticulum and discrete axonal cisternae at the axon hillock.

The axoplasmic reticulum (AR) and the discrete element (e.g., vesicles, vesiculotubular bodies, multivesicular bodies, etc.) constitute the endomembrane system of the axon. It is reported here that the AR of bullfrog sciatic nerve readily fills with osmium deposits during osmium impregnation. In contrast, the discrete elements and mitochondria are highly resistant to impregnation. Hence this preparation is well suited to address the nature of possible interactions between AR and rough endoplasmic reticulum (RER) in the axon hillock. It is also ideal to study the origin of the axonal discrete elements within the cell body as well as their interaction with other somal endomembrane system components. Tissues used in the present study were spinal ganglia, sciatic nerve, and spinal roots from Rana catesbeiana. Thick sections (1 to 2 microm) of this material were studied by high voltage electron microscopy. In some cases, osmium impregnation was followed by en bloc staining with lead aspartate. This made visible membranous structures that had not filled with osmium deposits during impregnation. Serial 170-nm-thick sections of this latter material were prepared and serial stereo pair electron micrographs of axon hillocks were collected. These were used to reconstruct three-dimensionally the AR and to study its relationship with RER and with discrete elements. The impregnated AR within the axon hillock was found to terminate as many proximally pointing finger-like projections. A large portion of these projections were found to form connections with RER. Some, however, terminated as true blind endings. Single unimpregnated discrete cisternae were found throughout the cytoplasm of the cell body, axon hillock, and axon. Large clusters of unimpregnated vesicles were usually found in close association with the trans face of the Golgi apparatus. These results indirectly support the hypothesis that vectors of fast axonal transport, namely the discrete elements, form directly at the trans face of the Golgi apparatus. From here they move toward and subsequently down the axon without any membrane fission-fusion events with either RER or AR. AR, although it forms continuities with RER, retains a distinctly different chemical composition from RER as evidenced by its much higher affinity for osmium. Thus, it should be considered as an endomembrane component separate from, although intimately related to the RER.

Animals↗
PubMed1985

The neuronal endomembrane system. II. The multiple forms of the Golgi apparatus cis element.

The cis element and its associated tubules and vesicles are ideally positioned to play a major role in the sorting of rough endoplasmic reticulum components destined for processing in the Golgi apparatus. Its position is also ideal for playing a major role in the assembly of the saccules which constitute the Golgi apparatus. The present study was undertaken to critically analyze the normal morphology of this Golgi apparatus component. Seventy- to 2000-nm-thick sections of bullfrog spinal ganglia, fixed by osmium impregnation as well as by conventional protocols, were studied using standard and high voltage electron microscopy. Impregnated cis elements were also reconstructed from 170-nm serial sections. These studies found that adjacent neurons within the given ganglion contain cis elements of widely different morphology. In larger neurons, a different cis element organization was also found in different regions of the same cells. Based on structural comparisons, all of the different cis element forms observed could be systematically assembled into a gradual continuum of morphological variation. This continuum was circular in a manner analogous to chromosomal variations seen in highly mitotic tissues. For the sake of discussion, five distinctly different form categories were established. Some forms contained structures that are described herein for the first time. Most notable among these is the cis tubular network, an extensive system of parallel tubules that closely apposed the regularly perforated cis saccule. Osmiophilic vesicles were found to collect in tight clusters that closely apposed certain forms of the cis element. These findings raise the possibility that the cis element and its associated structures may undergo morphological transformations as part of their normal function.

Animals↗
PubMed1984

Orthogonal arrays are redistributed in the membranes of astroglia from alumina-induced epileptic foci.

Freeze-fracture techniques were used to examine the distribution of orthogonal arrays in the membranes of astroglia from specimens of cerebral cortex of epileptic and control rats. Astroglial membranes from experimental chronic epileptic cortex displayed normal densities of arrays in pial-glial regions surrounding the alumina granuloma. Astroglial membranes from deep parenchymal regions of epileptic cortex displayed increased numbers of arrays, especially in regions of membrane not normally displaying arrays. The apparent random distribution of these membrane specializations in reactive astroglia in alumina-induced epileptic foci is discussed in reference to one postulation of orthogonal array function.

Aluminum↗
PubMed1983

The axoplasmic reticulum within myelinated axons is not transported rapidly.

The axoplasmic reticulum in myelinated axons is an extensive system of branched smooth membranous tubules which is found throughout the length of large axons. To investigate its motility and possible role in fast axonal transport, a focal chilling method was used to arrest transport at two sites separated by a 3 mm wide warm region along the saphenous nerve of mice. The experiments ran for 3-4 h since axoplasmic material travelling faster than 25 mm/day would clear from the central warm region. The nerve was subsequently fixed and processed by a technique that enhances the electron density of the axoplasmic reticulum. Thin and thick sections from several regions along the nerve were then systematically studied using conventional and high voltage electron microscopy. In these studies we found that: 1. the axoplasmic reticulum does not accumulate against the proximal sides of the cold blocks; 2. although often closely associated, there is no evidence of continuity between the axoplasmic reticulum and the discrete membranous compartments that do accumulate proximal to the chilled regions; 3. the axoplasmic reticulum remains in the central 3 mm wide warm region; 4. the axoplasmic reticulum does not accumulate against the distal sides of the cold blocks; 5. retrogradely moving elements that do accumulate distal to the cold blocks do not fuse with the axoplasmic reticulum and are not contained in it; and 6. both retrograde and anterograde vector types are often closely associated with elements of axoplasmic reticulum. These results were supported by quantitative morphometric analysis. We conclude that the axoplasmic reticulum represents a discrete membrane system, separate from either anterogradely or retrogradely moving rapid transport vectors, and that this interconnected cisternal system itself is not rapidly transported.

Animals↗
PubMed1983

Molecular morphology of the tetrodotoxin-binding sodium channel protein from Electrophorus electricus in solubilized and reconstituted preparations.

The appearance of detergent-solubilized voltage-regulated sodium channel protein was recently characterized by this laboratory. Negative-staining revealed rod-shaped particles measuring 40 X 170 A. Further studies have suggested that the actual configuration of this protein may be quite different from the rod-shaped structures. Freeze-fracture and freeze-etch images of the protein in reconstituted membranes indicated that the channel is cylindrical with a diameter of 100 A and a minimum length of 80 A. Experiments with two detergent systems (Lubrol-PX and sodium cholate) enabled us to explain the discrepancy between this structure and the rod-shaped particles visualized earlier. Negative staining in either detergent at low pH (4.5) produced rod-shaped structures. As the pH was increased, doughnut-shaped particles, consistent with the structure of the protein in freeze-etch, appeared in negative stain. The tendency of the protein to change shape under different pH conditions appears to be a peculiar property of this protein.

Animals↗
PubMed1982

Return of axonal and glial membrane specializations during remyelination after tellurium-induced demyelination.

We have studied remyelination of rat peripheral nerves after tellurium-induced demyelination using thin section and freeze-fracture techniques. In rats fed a 1% tellurium diet, regions of demyelination were readily identified by myelin debris and the presence of large denuded axons. Remyelination occurred despite continued tellurium ingestion. However, the demyelinated axons underwent a more rapid remyelination if tellurium was removed from the diet. Remyelination proceeded as described for myelination in the normal developing animal. Sites destined to become nodes of Ranvier were identified as patches of intramembranous particles in the axonal E-face. Early terminal loops of the remyelinating Schwann cell were found adjacent to these particle patches. As wrapping proceeded, terminal loops of myelin, along with associated rows of dimeric-particles characteristic of the axonal P-face, were wound into a paranodal location. This winding of the membrane specializations and associated terminal loops resulted in the reformation of morphologically normal paranodes. The size of the nodal E-face particle patch increased in concordance with increases in the number of paranodal loops until an annulus of particles was obtained as seen in the normal node. The thin section and freeze-fracture morphology of remyelinated fibres was indistinguishable from the morphology of control fibres. These observations are discussed with respect to proposed functions of membrane specializations in myelination and nerve conduction.

Animals↗
PubMed1982

The distribution of orthogonal arrays in the freeze-fractured rat median eminence.

The distribution of orthogonal arrays of particles and their relationships to gap and tight junctions have been studied in the glia of the freeze-fractured rat median eminence (ME). These rectilinear clusters of intramembrane particles are thought to represent trans-membrane channels for ions or metabolites, and were found to be densely packed on the membranous laminations of the pial-glial limitans. Additionally, arrays were found to be present on all of the perivascular glial end-feet examined. Two classes of end-feet were distinguished by their relative densities of orthogonal arrays. End-feet displaying low densities of arrays occurred more frequently in the internal zone, while end-feet displaying high densities occurred more often in the external zone. Similar distinctions based on array density could be made in membranes from other regions of the cell as well. Cross-fractures revealing the cytoplasm underlying these membranes often exposed lipid inclusion bodies, suggesting that membranes containing few arrays belong to tanycytes (or to 'astrocyte-like tanycytes'). The distribution of arrays appeared to be unrelated to the distribution of gap junctions in the membranes of astrocytes and tanycytes (and 'astrocyte-like tanycytes') of the ME, appearing near to and far from gap junctions with approximately equal frequency. Orthogonal arrays were absent from glial membranes near synaptic profiles in the ME. Arrays were also absent from the microvillous membranes of the apical surfaces of ependymal cells, from the cytoplasmic protrusions into the CSF of tanycytes, and from the vicinity of the tight and complex junctions linking the tanycyte and ependymal cell lateral membranes near their apical poles. These results suggest that there is a gradient of array density for most glia of the ME, increasing from the ventricular to the pial surface.

Animals↗