Local flow velocities in the cat carotid body tissue.

With the aid of a new three-dimensional mathematical model local flow velocities in the specific carotid body tissue of the cat measured by hydrogen clearances were calculated to have a mean value of 0.006 cm/s at a perfusion pressure of 50 mm Hg, 0.014 cm/s at a perfusion pressure of 120 mm Hg, and 0.018 cm/s at a perfusion pressure of 170 mm Hg. These results indicate that the carotid body specific tissue possesses a distinct flow heterogeneity with normal capillary flow velocities and a high shunt flow. During hypoxia, the smallest decrease in tissue PO2 was significantly correlated with the highest decrease in flow velocity. This suggests that the carotid body capillary network itself exhibits a PO2 sensor mechanism amplifying the chemoreceptive process in the specific cell elements.