Spatiotemporal properties of high speed calcium oscillations in the pedunculopontine nucleus

HYDE JR; KEZUNOVIC N; # URBANO FJ; # GARCIA-RILL E # URBANO FJ & GARCIA-RILL E CONTRIBUTED EQUALLY AS LAST AUTHORS.

JOURNAL OF APPLIED PHYSIOLOGY

AMER PHYSIOLOGICAL SOC

Lugar: Bethesda; Año: 2013 vol. 115 p. 1402 - 1414

8750-7587

---------------# Urbano FJ & Garcia-Rill E contributed equally as last authors. ------------------ The pedunculopontine nucleus (PPN) is a component of the reticular activating system (RAS), and is involved in the activated states of waking and rapid eye movement sleep (REM). Gamma oscillations (~30-80 Hz) are evident in all PPN neurons and are mediated by high threshold voltage-dependent N- and P/Q-type calcium channels. We tested the hypothesis that high speed calcium imaging would reveal calcium-mediated oscillations in dendritic compartments in synchrony with patch clamp recorded oscillations during depolarizing current ramps. Patch-clamped 8-16 day old rat PPN neurons (n = 67 out of 121) were filled with Fura 2, Bis Fura, or OGB1/CHR. This study also characterized a novel ratiometric technique using Oregon Green BAPTA-1 (OGB1) with co-injections of a new long-stokes-shift dye, Chromeo 494 (CHR). Fluorescent calcium transients were blocked with the nonspecific calcium channel blocker, cadmium, or by the combination of omega-agatoxin-IVA, a specific P/Q-type calcium channel blocker, and omega-conotoxin-GVIA, a specific N-type calcium channel blocker. The calcium transients were evident in different dendrites (suggesting channels are present throughout the dendritic tree), along the sampled length without interruption (suggesting channels are evenly distributed), and appeared to represent a summation of oscillations present in the soma. We confirm that PPN calcium channel-mediated oscillations are due to P/Q- and N-type channels, and reveal the fact that these channels are distributed along the dendrites of PPN cells.