Kw. Saupe et al., RESPIRATORY AND CARDIOVASCULAR-RESPONSES TO INCREASED AND DECREASED CAROTID-SINUS PRESSURE IN SLEEPING DOGS, Journal of applied physiology, 78(5), 1995, pp. 1688-1698
The purpose of this study was to determine the effects of changing blo
od pressure in the carotid sinus (Pcs) on ventilatory output during wa
kefulness and non-rapid-eye-movement sleep in unanesthetized dogs. Eig
ht dogs were chronically instrumented so that ventilation, heart rate,
and blood pressure could be measured while pressure in the isolated c
arotid sinus was rapidly changed by means of an extracorporeal perfusi
on circuit. Raising Pcs 35-75 mmHg consistently reduced ventilation 15
-40% in a dose-response fashion, with little or no further diminution
in minute ventilation as Pcs was further increased >75 mmHg above cont
rol level. This decrease in minute ventilation was immediate, due prim
arily to a decrease in tidal volume, and was sustained over the 20-s p
eriod of elevated Pcs. Increases in Pcs also caused immediate sustaine
d reductions in systemic blood pressure and heart rate, both of which
also fell in a dose-dependent fashion. The ventilatory and systemic ca
rdiovascular responses to increased Pcs were the same during wakefulne
ss and nonrapid-eye-movement sleep. Decreasing Pcs 40-80 mmHg caused a
sudden carotid chemoreceptor-mediated hyperpnea that was eliminated b
y hyperoxia. We conclude that increasing Pcs causes a reflex inhibitio
n of ventilation and that this reflex may play a role in sleep-disorde
red breathing.