The Study of Respiratory Chemoreflexes Using a Novel Dual-Perfused Rodent Preparation

Artificially perfused brainstem preparations have several advantages over both in vivo and superfused en bloc preparations for studying respiratory circuits. They allow the analysis of neuronal function without confounding influences of anesthesia and major peripheral feedback loops (chemoreceptor, vagal, and hormonal) while maintaining the brainstem in an oxygenated state and preserving many of the salient features of the normal respiratory motor pattern. Here we have summarized the development, characterization, and utility of a novel “dual-perfused preparation”: a vagotomized, decerebrate, in situ juvenile rat brainstem preparation in which central and peripheral chemoreceptors are perfused separately with defined media containing precisely controlled gas concentrations. This preparation has been instrumental in recent studies of time-dependent effects of chemoreflexes in response to intermittent chemostimuli as well as in demonstrating a hypoadditive interaction between central and peripheral chemoreceptors in the absence of cortical and vagal afferents (1–3).