Rhythmic slice preparations for the study of neuronal control of breathing usually contain the preBötzinger complex (PBC) and associated medullary respiratory centers. The activity of hypoglossal rootlets or PBC elements indicates ongoing respiratory-like activity. Recent studies suggest that respiratory rhythm generation also involves more rostral aspects like the parafacial region. Also, a potential role of the pontine Kölliker-Fuse is assumed. We developed a 700 mm rat brainstem slice that contains the PBC, parafacial region and Kölliker-Fuse. In this slice we imaged activity dependent intracellular Ca²⁺ changes (see abstract Funke et al.) to correlate population activity in the PBC with electrical mass activity. The novel slice preparation is characterized by a low frequency PBC mass activity of 3 burst/min (8 mM [K⁺]_o) compared to 6–12 bursts/minute in the "classic" PBC slice. Blocking inhibitory synapses with strychnine and bicuculline caused an initial, substantial augmentation of the PBC rhythm that stabilized at frequencies of 4–6 bursts/min. This response pattern reflects the situation after pontine ablation in en-bloc preparations. Therefore, our new slice preparation may prove substantial in the study of pontine modulation of PBC activity under a variety of physiological and pathophysiological conditions.

Supported by the DFG (CMPB) and Göttingen University