The kinetics of local tissue$P_{{\text{O}}_{\text{2}} }$ decrease after perfusion stop within the carotid body of the cat in vivo and in vitro

Summary

After perfusion stop a$P_{{\text{O}}_{\text{2}} }$ decrease has been measured in the carotid body tissue by means of elastically suspended$P_{{\text{O}}_{\text{2}} }$ needle electrodes. With the formula${\text{U}}_{{\text{O}}_{\text{2}} } = \frac{\alpha }{{760}} \cdot \frac{{\Delta P_{{\text{O}}_{\text{2}} } }}{{\Delta t}} \cdot 10^5$ it is possible to calculate the oxygen consumption from this$P_{{\text{O}}_{\text{2}} }$ decrease. Our experiments have shown that the oxygen consumption of the non-perfused carotid body of the cat depends linearly on local$P_{{\text{O}}_{\text{2}} }$. The$\frac{{\Delta P_{{\text{O}}_{\text{2}} } }}{{\Delta t}}$ measured in situ (Krebs-Henseleit perfusion) is with 6 Torr/s at a tissue$P_{{\text{O}}_{\text{2}} }$ of 100 Torr (37° C) two times higher than the values measured in vitro (Krebs-Henseleit-perfusion). The$\frac{{\Delta P_{{\text{O}}_{\text{2}} } }}{{\Delta t}}$ in vivo corresponds to an oxygen consumption of 1.2 ml O₂/100 g min at a$P_{{\text{O}}_{\text{2}} }$ of 100 Torr at 37° C. The$P_{{\text{O}}_{\text{2}} }$ dependence of the oxygen consumption of the carotid body might be caused by a special oxidase which may be involved in the chemoreceptive process.