Central-peripheral chemoreceptor ventilatory interaction in awake goats.

This study was designed to characterize the ventilatory interaction between central and carotid body (CB) chemoreceptor stimulation in awake goats undergoing selective CB perfusion. This model allowed us to expose central and CB chemoreceptors to separate blood gas conditions in an animal that is conscious and not systemically hypoxic. Systemic CO2 ventilatory response curves, performed by progressively increasing FICO2 in systemic hyperoxia, were completed in 7 goats during CB perfusion with hypercapnic-hypoxic blood and normocapnic-normoxic blood, and in 3 goats without CB perfusion. The slopes of the curves done with perfusion were not significantly different (P greater than 0.05) in CB hypercapnic hypoxia and CB normocapnic normoxia for VE, VT, f and VT/TI, and the coefficients of variation of slopes generated with and without perfusion were similar. Our data indicate there is addition of central and CB chemoreceptor input in respiratory control, and we conclude that the previously demonstrated stimulus interaction at the CB is the primary source of the hyperadditive hypercapnic-hypoxic ventilatory interaction in an animal unaffected by anesthetics or brain hypoxia.