Enlargement of carotid bodies in rats with lung emphysema or silicosis.

Volume of carotid bodies was measured morphometrically in rats with experimental lung emphysema or silicosis. The mean volume of the left carotid body was 19.9 +/- (SD) 12.4 in 13 control rats, 30.7 +/- 12.5 in 9 rats with lung emphysema, and 41 +/- 18.9 . 10(6) micrometer 3 in 10 rats with lung silicosis. There was no correlation between carotid body volume and pulmonary arterial blood pressure. A good correlation was found between the volume of carotid body and partial pressure of oxygen in arterial blood. The functional meaning of the increase of volume of carotid bodies in rats with chronic respiratory insufficiency remains unclear.