Good vibrations? Respiratory rhythms in the central control of blood pressure.

1. Arterial blood pressure is maintained, and reflexly controlled, by the activity of neurons in the medulla and spinal cord. 2. Rhythmic, automatic, respiratory activity is generated by neurons in the ventral medulla and transmitted to premotoneurons and motoneurons in the medulla and spinal cord. 3. Sympathetic nerve activity often has a respiratory rhythmicity. 4. One site at which the interaction between respiratory and sympathetic neurons occurs is the ventrolateral medulla. 5. Different types of sympathetic neurons, such as muscle vasoconstrictor, sudomotor and pilo-erector, have different patterns of respiratory rhythmicity. 6. Inputs from medullary respiratory neurons to medullary sympathetic premotor neurons may be the mechanism that co-ordinates the activity of these two vital systems.