Size of the carotid body and ventilatory responses to hypoxia in genetically hypertensive rats.

Structural and functional abnormalities of peripheral chemoreceptors have been found in association with hypertension in both man and rat. In New Zealand (NZ), Kyoto and Milan hypertensive (HT) rats carotid body volume was similar in HT and normotensive (NT) individuals of the same original genetic stock. Arteries within the carotid body showed changes typical of hypertension. Under anaesthesia, NZ HT rats had higher PaO2, lower PaCO2 tensions than NT rats; ventilation/100 g body weight was higher in the HT than NT rats over a wide range of inspired O2 tensions. Thus in HT rats we found evidence of hyperventilation without carotid body enlargement.