We are interested in understanding respiratory information coding in olfactory bulb (OB). When recorded in anaesthetized animal, mitral cells of the OB display respiratory-driven membrane potential slow oscillations around 2 Hz (MPSO) which are highly variable depending on the recorded cell. In fact, mitral cells can display depolarization during animal inspiration (MPSO+), hyperpolarization during inspiration (MPSO-) or no respiratory-driven oscillation (noMPSO) (Briffaud et al., 2012). Moreover, amplitude of MPSO varies from 1 to 15 mV. This variability of MPSO induces a variability of mitral cells spiking synchronization on the respiratory cycle. Mitral cells displaying MPSO+ present an increase of their spiking during inspiration (S+ pattern) while mitral cells displaying MPSO- present a decrease of their spiking during inspiration (S- pattern). Furthermore, we showed that the strength of the spiking synchronization on respiratory cycle is determined by the amplitude of the MPSO. Therefore, MPSO occurrence is of great importance in olfactory bulb information processing. Hyperpolarization-activated cationic current (Ih) expression is widely heterogeneous among mitral cells (Angelo et al., 2012). Ih is known to create a membrane potential resonance at low frequencies (2-6 Hz) which may increase the propensity of mitral cells to oscillate at MPSO frequency. Besides, Ih increases spiking precision during membrane potential oscillations in various neurons types. Therefore, we questioned if the Ih expression variability in mitral cells explain the variability of their response to respiration including MPSO type (MPSO+, MPSO-, noMPSO), MPSO amplitude and spiking synchronization to respiratory cycle. To address this question, we performed both in vitro and in vivo recordings of mitral cells using respectively patch clamp on OB slices and sharp electrodes intracellular recordings. In in vitro recordings, we tested if Ih expression produced a membrane potential resonance at MPSO frequency. We used in vivo recordings to explore the effect of Ih expression on mitral cell response to respiration. Our preliminary results seem to reveal no correlation between Ih expression and MPSO type or spiking synchronization of mitral cells.