Inhibition of fast axonal transport in vitro by tetracaine: an increase in potency at alkaline pH, and no change in potency in calcium-depleted nerves

1982 ◽  
Vol 60 (12) ◽  
pp. 1715-1720 ◽  
Author(s):  
P.-A. Lavoie
Keyword(s):  
Axonal Transport ◽  
Local Anesthetics ◽  
Smooth Endoplasmic Reticulum ◽  
Calcium Content ◽  
Alkaline Ph ◽  
Ph Change ◽  
Fast Axonal Transport ◽  
The Relationship ◽  
Normal Calcium

Some of the present in vitro experiments compare the degree of inhibition of fast axonal transport produced by tetracaine at neutral and at alkaline pH. In desheathed spinal nerves from bullfrog, 0.5 mM tetracaine reduced the quantity of [3H]leucine-labeled proteins which were transported to a ligature by 43% at pH 7.2 and by 96% at pH 8.2; separate experiments established that transport was not affected by the pH change in the absence of tetracaine. The relationship between pH and transport-blocking potency of tetracaine (pKa 8.2) is such that the local anesthetic is more potent when more uncharged form of the molecule is present; this may reflect the easier penetration across the axonal plasma membrane by the uncharged form of the tetracaine molecule. The axonal smooth endoplasmic reticulum has been attributed the function of a calcium reservoir, and it appeared possible that local anesthetics could block axonal transport by releasing calcium from this structure. However, the inhibition of transport produced by 1 mM tetracaine (pH 7.1) in sheathed nerves was approximately 80% both in nerves with a lower than normal calcium content (47% of normal) and in nerves with a normal calcium content; this result does not support the hypothesis that inhibition of axonal transport by local anesthetics is mediated by an increase in intracellular free Ca2+, but does not rule out the hypothesis either.

Inhibition of fast axonal transport in vitro by the local anesthetics prilocaine, mepivacaine, and bupivacaine

1983 ◽  
Vol 61 (12) ◽  
pp. 1478-1482 ◽  
Author(s):  
P.-A. Lavoie
Keyword(s):  
Axonal Transport ◽  
Local Anesthetics ◽  
Liquid Scintillation ◽  
Conduction Block ◽  
Scintillation Counting ◽  
Fast Axonal Transport ◽  
Spinal Nerves ◽  
Transport Inhibitors

The aim of the present study was to establish the concentrations of prilocaine, mepivacaine, and bupivacaine which are effective at blocking fast axonal transport, to determine whether prilocaine and mepivacaine offer a better prospect of dissociating conduction block and transport block in vivo than does lidocaine and whether bupivacaine offers a better prospect than etidocaine in the same context. Fast axonal transport of [3H]leucine-labeled proteins was studied in vitro in bullfrog spinal nerves and quantitated by liquid scintillation counting. Exposure of spinal nerves to 14 mM prilocaine reduced the quantity of 3H-labeled proteins which accumulated at a ligature by 86%, and exposure to 14 mM mepivacaine reduced it by 70%; 10 mM prilocaine reduced this same parameter by 54%, a degree of inhibition close to the 44% reduction caused by 14 mM lidocaine. The D(−) and L(+) stereoisomers of mepivacaine each reduced transport to the ligature by approximately 50% at a concentration of 14 mM. Bupivacaine reduced the accumulation of 3H-labeled proteins at the ligature by 49% at a 10 mM concentration (pH 6.2); its potency is close to that found for etidocaine in a previous study. Since prilocaine and mepivacaine are at least as potent as lidocaine as transport inhibitors and at blocking impulse conduction, these two anesthetics offer no advantage over lidocaine to achieve dissociation of conduction block from transport block in vivo. Bupivacaine appears to offer no advantage over etidocaine in the same context, as the two agents have a similar potency as local anesthetics and a similar potency as inhibitors of fast axonal transport.

Continuation of fast axonal transport in regenerating axons in vitro

1979 ◽  
Vol 57 (11) ◽  
pp. 1251-1255
Author(s):  
M. A. Bisby ◽  
C. E. Hilton
Keyword(s):  
Sciatic Nerve ◽  
Vagus Nerve ◽  
Axonal Transport ◽  
Nerve Injury ◽  
Axon Regeneration ◽  
Free Medium ◽  
Fast Axonal Transport ◽  
Sensory Axons

A previous study by McLean and co-workers reported that regenerating axons of the rabbit vagus nerve were unable to sustain axonal transport in vitro for several months after nerve injury. In contrast, we found that sensory axons of the rat sciatic nerve were able to transport 3H-labeled protein into their regenerating portions distal to the site of injury within a week after injury when placed in vitro. Transport in vitro was not significantly less than transport in axons maintained in vivo for the same period. Transport occurred in the medium that was used by the McLean group, but was significantly reduced in calcium-free medium. When axon regeneration was delared, only small amounts of activity were present in the nerve distal to the site of injury, showing that labeled protein normally present in that part of the nerve was associated with axons and was not a result of local precursor uptake by nonneural elements in the sciatic nerve. We were not able to explain the failure of McLean and co-workers to demonstrate transport in vitro in regenerating vagus nerve, but we conclude that there is no general peculiarity of growing axons that makes them unable to sustain transport in vitro.

Importance of monovalent ions for the fast axonal transport of proteins

1981 ◽  
Vol 59 (1) ◽  
pp. 31-36 ◽  
Author(s):  
P.-A. Lavoie
Keyword(s):  
Axonal Transport ◽  
Dorsal Root Ganglia ◽  
Dorsal Root ◽  
Time Course ◽  
Protein Transport ◽  
Choline Chloride ◽  
Fast Axonal Transport ◽  
Spinal Nerves ◽  
Monovalent Ions

Proteins labeled with [35S] methionine or [3H]leucine were generated in vitro in bullfrog dorsal root ganglia and their fast axonal transport in the spinal nerves was followed during a subsequent incubation period. Incubation of the ganglia in a medium where sucrose, choline chloride, or sodium isethionate replaced NaCl caused respectively an 88, a 37, or a 76% reduction in the quantity of proteins carried by the fast axonal transport system; no decrease in synthesis of labeled proteins was observed and protein transport followed the usual time course. Incubation of desheathed spinal nerves in a medium where sucrose replaced NaCl reduced by 67% the quantity of labeled proteins which were transported past the desheathed region. Although both the axons and the dorsal root ganglia exhibit the requirement for monovalent ions to maintain fast axonal transport, the possibility that the ionic requirements of the ganglia pertain to the somal portion of the nerve cell is discussed.

Mechanisms of the inhibition of fast axonal transport by local anesthetics

1989 ◽  
Vol 28 (2) ◽  
pp. 175-181 ◽  
Author(s):  
P.-A. Lavoie ◽  
T. Khazen ◽  
P.R. Filion
Keyword(s):  
Axonal Transport ◽  
Local Anesthetics ◽  
Fast Axonal Transport

scholarly journals Immunochemical analysis of kinesin light chain function.

1997 ◽  
Vol 8 (4) ◽  
pp. 675-689 ◽  
Author(s):  
D L Stenoien ◽  
S T Brady
Keyword(s):  
Axonal Transport ◽  
Light Chain ◽  
Membrane Vesicles ◽  
Retrograde Transport ◽  
Light Chains ◽  
Fast Axonal Transport ◽  
Kinesin Light Chain ◽  
Punctate Pattern ◽  
Conventional Kinesin

The kinesin heterotetramer consists of two heavy and two light chains. Kinesin light chains have been proposed to act in binding motor protein to cargo, but evidence for this has been indirect. A library of monoclonal antibodies directed against conserved epitopes throughout the kinesin light chain sequence were used to map light chain functional architecture and to assess physiological functions of these domains. Immunocytochemistry with all antibodies showed a punctate pattern that was detergent soluble. A monoclonal antibody (KLC-All) made against a highly conserved epitope in the tandem repeat domain of light chains inhibited fast axonal transport in isolated axoplasm by decreasing both the number and velocity of vesicles moving, whereas an antibody against a conserved amino terminus epitope had no effect. KLC-All was equally effective at inhibiting both anterograde and retrograde transport. Neither antibody inhibited microtubule-binding or ATPase activity in vitro. KLC-All was unique among antibodies tested in releasing kinesin from purified membrane vesicles, suggesting a mechanism of action for inhibition of axonal transport. These results provide further evidence that conventional kinesin is a motor for fast axonal transport and demonstrate that kinesin light chains play an important role in kinesin interaction with membranes.

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