The correlation between calcium absorption and electrophysiological recovery in crushed rat peripheral nerves

Abstract

The correlation between calcium ion (Ca2+) concentration and electrophysiological recovery in crushed peripheral nerves has not been studied. Observing and quantifying the Ca2+ intensity in live normal and crushed peripheral nerves was performed using a novel microfine tearing technique and Calcium Green-1 Acetoxymethyl ester stain, a fluorescent Ca2+ indicator. Ca2+ was shown to be homogeneously distributed in the myelinated sheaths. After a crush injury, there was significant stasis in the injured zone and the portion distal to the injury. The Ca2+ has been almost completely absorbed after 24 weeks in the injured nerve to be similar to the controls. The process of the calcium absorption was correlated with the Compound Muscle Action Potential recovery process of the injured nerves. This correlation was statistically significant (r = -0.81, P < 0.05). The better understanding of this process will help us to improve nerve regeneration after peripheral nerve injury.

Myelin abnormality in Charcot–Marie–Tooth type 4J recapitulates features of acquired demyelination

“…Because Ca 2+ is already increased in Fig4 −/− Schwann cells 11 , a further increase of cytosolic Ca 2+ level likely initiates a cascade of events leading to demyelination 39 . In line with this idea, axonal damage has been shown to increase intracellular Ca 2+ level in myelin 41 . It is also interesting to note that depletion of macrophages by the treatment of CSF1R receptor inhibitor improved pathology in two inherited neuropathy mouse models 42 .…”

“…40 In line with this idea, axonal damage has been shown to increase intracellular Ca 21 level in myelin. 42 It is also interesting to note that depletion of macrophages by the treatment of CSF1R receptor inhibitor improved pathology in 2 inherited neuropathy mouse models. 43 It should be clarified that our findings do not exclude developmental abnormality of myelin (dysmyelination) in CMT4J.…”

Calcitonin pump improves nerve regeneration after transection injury and repair

“…The stimulus was a square electric pulse with a voltage of 19 mV, duration of 0.01 ms, and frequency of 1 H z . During these procedures, the room temperature was controlled at 25°C, and a heating pad maintained rat body temperature at 37°C, as measured by a rectal temperature probe …”

“…). Calcium fluorescence of the nerve fibers was measured using our published method . The nerves were placed in 1.5‐ml Eppendorf tubes with the staining solution, which contained 7 μg of calcium green‐1 acetoxymethyl (AM) ester (Molecular Probes/Invitrogen, Carlsbad, California) dissolved in 7 μl of 20% Pluronic F‐127/dimethylsulfoxide (Molecular Probes/Invitrogen) and further diluted in 1 ml of Dulbecco modified Eagle medium without phenol red.…”

“…This is the area between normal nerve fibers, and its mean value is 14.16 ± 1.34 RFU. This number is equal to the calcium concentration in the extracellular environment, which has been found to be 1 × 10 −3 M. One RFU would be equal to a calcium concentration of 7.14 × 10 −5 M. Using basic algebra, we calculated the calcium concentrations of the various nerve segments from earlier studies …”