Distribution of oxygen partial pressure in the carotid body region and in the carotid body (rabbit).

In the specific tissue of the rabbit carotid body as well as in the connective tissue surrounding the organ, pO distribution was measured with membranecovered needle electrodes (tip diameter 1-2 μm). The histograms resulting from measurements in the specific tissue were shifted to low pO values as compared to other tissues. The oxygen blowing test, i.e. exposure of the carotid boyd to humidified 100% oxygen was employed to decide upon the site of measurement: pO increased when the electrode measured in the surrounding tissue (type 1 response); pO remained stable or slightly decreased when the electrode sampled in the specific carotid body tissue (type 2 response). After the experiment, the electrode track was reconstructed from histological serial sections and the type of reaction was related to the type of tissue. Low pO values were found to prevail in the specific carotid body tissue, which leads to the conclusion that the amount of low pO values determines the degree of chemoreceptor activity. [ABSTRACT FROM AUTHOR]