Local oxygen tension field in the glomus caroticum of the cat and its change at changing arterial PO 2 .

Abstract

1. The distribution of oxygen tension has been measured in the carotid body of 97 cats using platinum microelectrodes. In only seven cats was there evidence from measurement of chemoreceptor afferent discharge in the sinus nerve of damage to carotid body tissue or blood vessel. 11 carotid bodies were histologically controlled, 2 showed obvious damages of the puncture. 2. The distribution of oxygen tension in carotid body tissue was consistent with very few exceptions and consisted of a relatively highPO2 (ca. 25–90 mm Hg) at the greatest distance from the surface progressively falling toward the surface where there was a zone of low oxygen tension, 0–15 mm Hg and then a barrier to the inward diffusion of oxygen. 3. This pattern of oxygen tension distribution was altered to the point of reversal following death of the animal and following injections of antimycin into the common carotid artery. The surface barrier to oxygen could also be reduced or abolished with antimycin and local destruction of tissue by electrolysis. 4. The frequency distribution of tissuePO2 showed that 79% of all values obtained were less than 40 mm Hg. The local tissuePO2 and the distribution ofPO2 was systematically altered by changes inPaO2, the alterations being least conspicuous in the outer zone of lowPO2. 5. These results provide some evidence that blood flow through the carotid body is far from homogeneous. The various mechanisms which may be involved are discussed.