Tissue-PO2 (PGO2) in the carotid body of the cat and tidal volume (V) during normovolaemic haemodilution.

During normovolaemic haemodilution with Macrodex (R), the basic respiratory activity is unchanged, while the ventilatory responses to hypoxia and hypercapnia generally decrease. The PGO2 in the cat carotid body remains constant down to an Hk of 10% to 15% and then decreases. This confirms the suggestion of Acker and Lübbers (1976) that increased plasma flow through the carotid body does not influence the oxygen supply to this organ, despite variations of both oxygen transport capacity and haemoglobin concentration. The fine structure of the carotid body is partly destroyed by haemodilution with Macrodex (R) and this could account for the impaired chemoreception.