The effects of unilateral carotid body excision on ventilatory control in goats.

The purpose of this study was to determine whether or not unilateral carotid body excision (UCBE) alters normal respiratory control in awake and otherwise intact goats. We measured resting VE and blood gas tensions and pH and ventilatory responses (VR) to NaCN, dopamine and Doxapram in awake goats before and after UCBE. Resting ventilation, blood gas tensions and pH, and the VR to the above stimuli were not altered by UCBE. During exposure to hypoxia in a hypobaric chamber (PB = 450 torr), PaCO2 decreased in UCBE goats over the first hour, indicating acute hypoxic hyperventilation. During the subsequent 8 h, PaCO2 decreased an additional 5-6 torr, suggesting ventilatory acclimatization to chronic hypoxia (VACH). The response was similar to that observed in intact goats. Acute normoxia following 6 and 8 hr did not completely alleviate the hypocapnia of prolonged hypoxia, further suggesting VACH. We conclude that sufficient redundancy exists in the inputs from the paired carotid body chemoreceptors so that normal ventilatory responsiveness to acute and chronic stimuli is present in goats possessing only a single carotid body.