Oscillatory currents generated by bundles of brain microtubules

CANTERO MR; VILLA ETCHEGOYEN C; PEREZ PL; SCARINCI N; CANTIELLO HF

Congreso; Reunión Conjunta de Sociedades de Biociencias.; 2017

Microtubules (MTs) are unique components of the cytoskeleton formed by hollow cylindrical structures of tubulin dimeric units. A variety of other microtubular organizations are often observed, including two-dimensional sheets and bundles. The structural wall of the MT is interspersed by nanopores formed by the lateral arrangement of its subunits. Two-dimensional arrangements of tubulins display spontaneous oscillatory electrical behavior elicited by voltage and/or ionic gradients. Because of the potentially relevant implications of these electrical oscillations in cellular physiology, we explored this phenomenon in bundles of microtubules, heretofore known as macrotubules. Voltage-clamped MT macrotubules were studied by the patch clamp technique. For this study macrotubule bundles obtained from rat brain were utilized. Despite the fact that these structures did not render high resistance seals, as recently reported for two-dimensional MT sheets (Cantero et al, Sci Rep, 2016), we detected and preliminarily characterized highly regular electrical oscillations in this preparation. Thus, we obtained direct evidence for the presence of cation-selective oscillatory electrical currents. The oscillations progressed through various periodic regimes, being prominent a fundamental frequency at 39 Hz. In physiological K+ (140 mM), the electrical oscillations represented, in average a 625 ± 21 % change in conductance (p