Role of calcium in the initiation of fast axonal transport of protein: Effects of divalent cations
- 1 September 1977
- journal article
- research article
- Published by Wiley in Journal of Neurobiology
- Vol. 8 (5) , 439-451
- https://doi.org/10.1002/neu.480080505
Abstract
Fast axonal transport of [3H]protein has been examined in bullfrog primary afferent neurons incubated in media supplemented with divalent cations that can act as agonists or antagonists of calcium ions. Incubation in calcium‐free medium (CFM) had no effect on the rate of transport, but reduced the amount of transported [3H]protein by 40–60% relative to transport in the contralateral preparation maintained in normal medium. Preparations incubated in CFM supplemented with 1.8 mM SrCl2 (equimolar to the CaCl2 concentration in normal medium) carried out transport at control levels. Incubation conditions in which primary afferent somata were exposed to the Sr2+‐medium while nerve trunks were maintained in CFM also supported normal transport. By contrast, selective exposure of nerve trunks to Sr2+‐medium, and somata to CFM resulted in a reduced level of transport similar to that observed when the whole preparation was incubated in CFM. The depression of transport resulting from incubation in CFM was shown to be reversible when preparations were transferred from CFM to either Sr2+‐supplemented CFM or to normal medium. By contrast to the effects of Sr2+, Ba2+ (up to 18 mM) did not substitute for Ca2+ in the transport process. When normal medium was supplemented with calciumantagonist cations, the amount of transport was depressed (Co2+ > Mn2+ >> Mg2+), with no concomitant effect on the rate of transport. Results of studies with Co2+, as well as those with Sr2+, suggest that a major locus of action of these cations is within the neuronal soma at a step subsequent to protein synthesis, and prior to the onset of protein translocation via the transport system. Thus, it is inferred that these divalent cations affect a calcium‐dependent step that occurs during the initiation phase of fast axonal transport.Keywords
This publication has 45 references indexed in Scilit:
- UPTAKE OF NEUROTRANSMITTER CANDIDATES BY PIGEON OPTIC TECTUMJournal of Neurochemistry, 1976
- The effect of electrical stimulation on the distribution of labelled proteins in isolated segments of rabbit vagus nerveJournal of Neurochemistry, 1975
- Distribution along the axon and into various subcellular fractions of molecules labeled with [3H]leucine and rapidly transported in the garfish olfactory nerveBrain Research, 1975
- Studies on bursting pacemaker potential activity in molluscan neurons. I. Membrane properties and ionic contributionsBrain Research, 1975
- Studies on intracellular transport of secretory proteins in the rat exocrine pancreasVirchows Archiv, 1975
- Structural correlates of rapid axonal transfort: Evidence that microtubules may not be directly involvedBrain Research, 1974
- The inhibitory effect of manganese on transmitter release at the neuromuscular junction of the toadBritish Journal of Pharmacology, 1973
- Transport and metabolism of calcium ions in nerveProgress in Biophysics and Molecular Biology, 1972
- Depolarization and calcium entry in squid giant axonsThe Journal of Physiology, 1971
- The effects of alkaline earths and other divalent cations on adrenal medullary secretionThe Journal of Physiology, 1964