抄録
Analyses of respiratory neuron activity by voltage-sensitive dye imaging in the brainstem-spinal cord preparation of postnatal day 0 or 1(P0-P1) rat or mouse have revealed a characteristic activity pattern in the rostral ventral medulla; preinspiratory activity in the rostral medulla (corresponding to para-facial respiratory group) preceding inspiratory activity in the more caudal medulla (corresponding to pre-Botzinger complex) (e.g. Onimaru & Homma, 2003). On the other hand, postnatal changes of organization of the respiratory neuron network remain to be elucidated, whereas P4-P5 rat or mouse is limitation age for experimental usage of the en bloc reparation. In the present study, we analyzed respiratory neuron activity by voltage-sensitive dye imaging (network level) and whole-cell patch clamp recordings (individual cell level) in the ventral medulla of P0-P5 rats and mice. We found that basically same activity pattern was detected in P0-P4 rats and P0-P5 mice, while the fluorescence intensity (S/N ratio) tended to decrease with age especially in the rat. In the mouse, application of low concentration (0.1-0.2 μM) of adrenaline was effective to induce regular respiratory activity in P0-P1 preparations, whereas this treatment was not necessary to obtain regular C4 activity and conspicuous spatio-temporal pattern of respiratory neuron activity in P4-P5 preparations. Using whole-cell recordings, we also confirmed presence of subtypes of respiratory neurons that show burst pattern corresponding to imaging data. [J Physiol Sci. 2008;58 Suppl:S116]
