ROLE OF CAROTID-BODY IN PRESSURE RESPONSE OF PULMONARY CIRCULATION INRATS

We investigated how signals arising from peripheral chemoreceptors cou ld affect pulmonary vasculature in rats. Effects of the hypoxic exposu re (10%) on mean pulmonary arterial pressure (mPAP), abdominal aortic flow ((Q) over dot) and the estimated total pulmonary vascular resista nce (mPAP/(Q) over dot) were determined in anesthetized, artificially ventilated, carotid sinus nerve intact or chemodenervated rats. The pr esser response of PAP to hypoxia seen in intact rats changed to the de pressor response after chemodenervation. Hypoxia elicited a decrease i n (Q) over dot and an increase in mPAP/(Q) over dot in both intact and chemodenervated rats. Selective carotid body stimulation by the intra -carotid injection of sodium cyanide (NaCN) in normoxia elicited an im mediate but transient increase in PAP and (Q) over dot before and afte r bilateral vagotomy. The peak change in PAP slightly preceded that in (Q) over dot. These responses to NaCN were completely abolished by ch emodenervation. These results indicate that the immediate chemoreflex contributes to the short-term regulation of pulmonary vasculature in r ats. (C) 1998 Elsevier Science B.V. All rights reserved.