Article: PDF OnlyBrain-Stem Mechanisms Governing Resting and Reflex Tone of Precapillary VesselsReis, D. J. Author Information Laboratory of Neurobiology, Department of Neurology, Cornell University Medical College, New York, U.S.A. Journal of Cardiovascular Pharmacology 7():p S160-S166, Free Abstract The sympathetic drive to the cardiovascular system depends on the integrity of neurons in the medulla oblongata. The adrenergic neurons of the Cl-area of the cortical ventrolateral medulla are tonically active and provide the background excitation of the spinal pregan-glionic neurons, which relay to the postganglionic sympathetic neurons. The noradrenergic neurons of the Al-area of the caudal ventrolateral medulla act as tonic inhibitors of the sympathetic discharge; they mediate the depressor response to centrally acting α-adrenergic agonists such as clonidine. Imbalance between those two types of neuronal control systems leads to increased sympathetic discharge and hence elevated arterial blood pressure. © Lippincott-Raven Publishers.
