Peripheral arterial chemoreceptors and hypertension.

Functional studies in humans and animals with essential hypertension have shown a hyperventilation under resting conditions and striking respiratory and circulatory reactions to hypoxic and hyperoxic tests. There is some evidence that these reactions are due to enhanced activity of the peripheral arterial chemoreceptors. In contrast, in secondary (renal) hypertension such findings could not be observed. Many morphological, morphometrical and biochemical studies have been performed on the carotid bodies of a variety of hypertensive patients and animal models. Whilst their structure and catecholamine content are changed in hypertension, there are many differences in different types of hypertension and, furthermore, a convincing link between the morphological and biochemical findings from the carotid body studies and their functional overactivity has not been shown. Some of these alterations are caused by the elevated blood pressure (e.g. vascular pathology); others are the expression of general disturbances in the hypertensive disease state (e.g. differences in catecholamine content) whilst others are probably of genetic origin but independent of elevated blood pressure (carotid body volume in different rat models of hypertension). This paper reviews the findings on carotid body structure and function in a variety of animal models of hypertension and in primary and secondary human hypertension.