The Role of Calcium in Axoplasmic Transport in Mammalian Nerve Fibers

Ochs, Sidney; Chan, S. Y.; Iqbal, Zafar; Worth, Robert M.; Jersild, Ralph A.

doi:10.1016/b978-0-444-80079-4.50015-6

Cited by 8 publications

(7 citation statements)

References 23 publications

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“…The role of internal Ca concentration in controlling the assembly and distribution of microtubules as well as the movement of granules along microtubules (41) suggests the possibility that the density and activity of Ca channels in or near the growth cones play crucial roles in governing the form of outgrowth. We were thus interested to find that cells of branching morphology have much smaller Ca currents than those reported above for large veiling cells, although these observations must be regarded as preliminary.…”

Section: Discussionmentioning

confidence: 99%

Crustacean peptidergic neurons in culture show immediate outgrowth in simple medium.

Cooke

Graf

Grau

et al. 1989

Proc. Natl. Acad. Sci. U.S.A.

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The survival and outgrowth of neurons in culture has usually required conditioning factors. We now report that crustacean neurons, taken from the peptidergic neurosecretory system of the eyestalk of crabs (Cardisoma carnifex) and lobsters (Panulirus marginatus), show immediate outgrowth, sustained for a week or more, in defined medium as simple as physiological saline with glucose and glutamine.The neurons show peptide hormone immunoreactivity that is prominent at growth cones, exhibit differences in form correlated with their immunoreactivity, release peptides to the medium, and have voltage-dependent currents, including a well-sustained Ca current. Cd blocks secretion, growth, and the Ca current. Peptidergic secretory neurons may be able to utilize existing membrane from their store of granules and already active synthetic, transport, and secretory mechanisms for immediate outgrowth.The mechanisms governing the outgrowth of neuronal processes and the mature form of neurons remain largely unknown. Isolation of neurons in culture may provide the possibility of undertaking experimental manipulations under controlled conditions. However, although outgrowth in lowdensity cultures has now been demonstrated for vertebrate (1-5), annelid (6, 7), and molluscan (8-11) preparations, the need for addition of undefined factors has frustrated rigorous studies of the control of outgrowth and form. We report that crustacean neuroendocrine cells show immediate, vigorous outgrowth on a variety of substrates in defined medium as simple as physiological saline and glucose. We propose that this capability for immediate outgrowth is made possible by the utilization of already active synthetic, transport, and secretory mechanisms for growth. Different forms of outgrowth are consistently obtained from the heterogeneous group of neurons cultured, and reactivity with antisera raised against peptide hormones suggests correlations with the biosynthetic capabilities of the neurons. These neurons in culture, with their differences in form, thus provide a promising defined starting point for testing hypotheses about mechanisms governing the control of growth and form in regenerating neurons. We are unaware of any report of crustacean neurons in culture (12). Abstracts describing some of our work have appeared (13)(14)(15).The neurons cultured in these studies form the major neuroendocrine system of crustaceans, the X-organ-sinus gland system of the eyestalk (ref. 16 and, for review, see ref. 17). For the tropical land crab Cardisoma carnifex used for most of the work to be discussed, there have been studies of the morphology of nerve terminals (18), electrophysiological characterization of somata, axons, and terminals (19)(20)(21)(22), studies of secretory capabilities (22,23), and characterization of the hormonal peptides present (24) and their biosynthesis (25). These provide a background against which the cultured cells can be evaluated.The X-organ of crabs is a discrete cluster of about 200 iridescent-white neuronal somata (26)...

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Section: Discussionmentioning

confidence: 99%

Crustacean peptidergic neurons in culture show immediate outgrowth in simple medium.

Cooke

Graf

Grau

et al. 1989

Proc. Natl. Acad. Sci. U.S.A.

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“…This is the level of free Ca2+ required by the calmodulin present in mammalian nerve to allow its activation of Ca-Mg-ATPase (Iqbal and Ochs, 1980). In the model, the Ca-Mg-ATPase is associated with the microtubule sidearms and can utilize the -P of ATP causing the sidearms to move the transport filaments and in turn, the various materials bound to them down within the axons (Ochs et al, 1978;Ochs, 1981a,b). For such action, a regulation of [Ca2+] within an optimal range for activation of the calmodulin-Ca-Mg-ATPase is necessary.…”

Section: Mode Of Action Of Increased Axonal Na+ Levels On the Transpomentioning

confidence: 99%

Dependence of batrachotoxin block of axoplasmic transport on sodium

Worth

Ochs

1982

J. Neurobiol.

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Batrachotoxin (BTX) in the low concentration range of 19-190 nM blocks axoplasmic transport in the desheathed cat peroneal nerve in vitro. When the level of Na+ in the incubation medium was reduced to 10 mM, the blocking effect of BTX was much diminished, and in an Na+-free medium BTX had no effect on transport at all. The blocking action of BTX with Na+ present was inhibited by increasing the concentration of Ca2+ in the experimental medium. Relatively small increases were effective with a maximum protection seen when the Ca2+ concentrations were 7-10 mM. The results support the view that an increase in axonal Na+ is inhibitory to the transport mechanism. The results are discussed on the basis of the recently developed transport filament model of axoplasmic transport which takes into account an obligatory role for Ca2+ in transport and its axonal regulation. The possible relation of intraaxonal Na+ concentration to the Ca2+ level is also discussed.

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“…Frog, sciatic nerve, axonal transport, transplantation Fast axonal transport has been extensively studied in both mammalian and non-mammalian vertebrates (for reviews see Heslop 1975, Lubinska 1975. In mammalian sciatic nerves the rate of protein transport is about 400 mm/day at 37°C (Ochs 1972, Hanson 1978 while in frog sciatic nerves the rate is 125 mm/day at 18°C (Edstrom & Hanson 1973rr). In other respects the transport characteristics seem to be similar (Edstrom & Mattsson 1972, Cosens eta].…”

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confidence: 99%

Axonal transport in transplanted frog sciatic nerve

Hanson

1981

Acta Physiologica Scandinavica

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Axonal transport was studied in transplanted frog sciatic nerves-dorsal ganglia for periods up to three months. The ganglia were either labeled prior to, or after varying periods of transplantation and the distribution of labeled proteins compared. The survival of the preparations was assessed by studying their ability to transmit compound action potentials, to maintain axonal transport and by their ultrastructural appearance. The sensory neurons retained their fast axonal transport and excitability during the transplantation periods. Morphologically about 30% of the axons appeared normal after one month of transplantation. The amount and distribution of protein incorporated radioactivity in the ganglia and the nerve changed with time but the decrease in the ganglia was not accompanied by a corresponding increase in the nerve. There was no evidence for a distinct slow phase of transport in spite of a functional fast transport system. The results indicate that either slow transport stops when the normal balance between release, degradation and recirculation is distributed by the presence of a ligature or that there is a continuous change in the composition of transported material with the time after labeling which is not reflected in altered transport characteristics.

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The Role of Calcium in Axoplasmic Transport in Mammalian Nerve Fibers

Cited by 8 publications

References 23 publications

Crustacean peptidergic neurons in culture show immediate outgrowth in simple medium.

Crustacean peptidergic neurons in culture show immediate outgrowth in simple medium.

Dependence of batrachotoxin block of axoplasmic transport on sodium

Axonal transport in transplanted frog sciatic nerve

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