Affiliations: Department of Biophysics, School of Medicine,
University of Cukurova, 01330 Balcali, Adana, Turkey | Department of Histology, School of Medicine,
University of Cukurova, 01330 Balcali, Adana, Turkey
Note: [] Corresponding author: Dr. Tufan Mert, Ph.D, Department of
Biophysics, School of Medicine, University of Cukurova, 01330 Balcali, Adana,
Turkey. Tel.: +90 322 3386060; Fax: +90 322 3386572; E-mail:
tufanmert@yahoo.com
Abstract: Purpose: Nerve crush injury results in the incapability to maintain
conduction of an impulse. Disruption in the myelin sheath causes very important
changes in the activities of ion channels. Therefore, crushed and intact
sciatic nerves were researched with both histological and electrophysiological
methods in this study. Methods: Electron and light microscopy for histological
examinations, a sucrose-gap recording techniques for electrophysiological
examinations were used. 4-aminopyridine (4-AP) and Tetraethylammonium (TEA)
were used to functional separation of the fast and slow
K^+ channels. Results: The number of damaged myelinated nerve fiber was counted as
750 ± 3.5. Lamellar separation and disruption in myelin sheath was
frequently observed in these fibers. Conduction velocity of crushed nerves (19
± 2 m/s) was half of the intact nerves. The relationship between
equally spaced interstimulus interval and their responses demonstrated that
4-AP and 4-AP plus TEA have more pronounced effects on crushed nerves than on
intact nerves. After 4-AP, TEA application caused an efficiently depolarization
in the membrane potential. Conclusions: The effects of 4-AP and 4-AP plus TEA suggest the
involvement of slow and fast K^+ channels and
slow Na^+ currents in membrane potential and
action potential repolarization. Minimal myelin damage may significantly
influence the subsequent impulse generation and the patterning of action
potential activity.
