Autonomic blood pressure control.

The regulation of systemic arterial blood pressure is key to survival. The sympathetic and parasympathetic regulation of arterial blood pressure requires information related to the actual blood pressure values for feedback control as well as integration with the ongoing behavior, including physical exercise and sleep, and with the regulation of breathing and body temperature. The brainstem includes the core neural circuitry underlying control of autonomic preganglionic neurons; integration of the baroreceptor, chemoreceptor, and exercise pressor reflexes; and integration of behavioral responses with central autonomic commands associated with physical exercise, sleep, and arousal. As a result, alterations in the central autonomic network of the brainstem may cause severe impairment in the regulation of arterial blood pressure. These alterations lead to afferent baroreflex failure and to cardiovascular autonomic failure with neurogenic orthostatic hypotension and supine hypertension, or occur as a result of neurodegeneration in multiple system atrophy or of multiple sclerosis and brainstem lesions. A better understanding of the brainstem circuitry involved in the regulation of arterial blood pressure may also shed light on the mechanisms of arterial hypertension, which is a powerful risk factor for adverse cardiovascular events.