Cardiorespiratory reflexes in a working heart–brainstem preparation of the house musk shrew, Suncus murinus

In this study, we adapted the working heart–brainstem preparation (WHBP) from rodents to the Insectivore, Suncus murinus. Suncus WHBPs had a baseline heart rate of 333±8 beats min−1, a perfusion pressure of 69±2 mm Hg and a respiratory cycle length of 6.5±0.7 s. Administration of atropine produced an increase in heart rate of 26±9 beats min−1, indicative of the presence of cardiac vagal tone. Activation of baroreceptors produced pressure-dependent reflex falls in heart rate and reduced respiratory cycle length. The baroreceptor reflex sensitivity in Suncus WHBP was a decrease in heart rate of 8.1±1.4 beats min−1 mm Hg−1. Activation of peripheral chemoreceptors with aortic injections of sodium cyanide (0.1–12.5 μg) produced a dose-dependent reflex fall in heart rate and reduced respiratory cycle length. The reflex falls in heart rate evoked by baroreceptor and peripheral chemoreceptor stimulation were both atropine-sensitive. We conclude that viable WHBP can be prepared from Suncus and that Suncus WHBP is a novel non-rodent model in which to study brainstem-mediated reflexes.