Agonistic effects of xanthines on tetrodotoxin-sensitive sodium channels in the rat dorsal root ganglion neurons |
| |
Authors: | N T Parkhomenko L N Yatsenko A M Kuksenok |
| |
Institution: | (1) Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kiev, Ukraine |
| |
Abstract: | The effects of four xanthine derivatives, caffeine, caffeine benzoate, theophylline, and bromtheophylline, on sodium channels
in internally perfused rat dorsal root ganglion neurons were studied under voltage-clamp and whole-cell patch-clamp conditions.
Reversible acceleration, enhancement of the amplitude of sodium currents, and shifts of the current-voltage relation (plotted
for their maxima), as well as of the steady-state inactivation curve toward more negative potentials, were observed at external
applications of the above substances in the concentrations of 0.2–4.0 mM. Under long exposures, inactivation of sodium currents
became slower in a part of the cells. Yet, when the exposure to 4 mM or higher concentrations was longer than 10 min, a rise
in the passive conductance was obvious, and functional state of the cells became worse. Blocking effects of the xanthine derivatives
on transient or delayed potassium currents were not observed. Thus, agonistic action of xanthines on sodium channels has been
demonstrated, and it is supposed that a considerable component of their pharmacological effects is provided by the action
on Na+/Ca2+ exchange. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|