Baroreflex function and centrally acting antihypertensive drugs
The baroreflex is a neural circuit that has powerful effects on blood pressure and heart rate. First recognized in the 1920s (Koch and Mies 1929), it is now known to involve sensory endings (arterial baroreceptors) in both the carotid sinus and the aortic arch. These produce afferent impulses which are transmitted via the glossopharyngeal (carotid) and vagus (aortic) nerves to synapses within the nucleus tractus solitarius of the medulla. Ultimately, blood pressure and heart rate are affected by parallel sympathetic and parasympathetic modulation. Following the initial description of the baroreflex, it was speculated that a primary disturbance of its function might lead to hypertension in man. This speculation remains active today, supported by observations that impairment of the baroreflex function can produce hypertension in animals and in man. The development of centrally acting antihypertensive drugs, including clonidine hydrochloride, has provided further information about the neurophysiology of the baroreflex, including evidence that baroreflex modulation may be a component action of such drugs.
KeywordsCarotid Sinus Nucleus Tractus Solitarius Baroreflex Sensitivity Baroreflex Function Sustained Hypertension
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- 6.Eckberg DL (1979) Carotid baroreflex function in young men with borderline blood pressure elevation Circulation 59: 623–636.Google Scholar
- 9.Haeusler G (1977) Neuronal mechanisms influencing transmission in the baroreceptor reflex arc. In: De Jong W, Provoost SP, Shapiro AP (eds), Hypertension and Brain Mechanisms, Prog Brain Res 47: 95–109.Google Scholar
- 11.Koch E, Mies A (1929) Chronischer arterieller Hochdruck durch experimentelle Dauerausschaltung der Blutdruckzügler. Krankheitsforsch 7: 241–256.Google Scholar
- 20.Simon AC, Safar ME, Weiss YA, London GM, Milliez PL (1977 a) Baroreflex sensitivity and cardiopulmonary blood volume in normotensive and hypertensive patients. Br Heart J 39: 799–805.Google Scholar
- 21.Simon G, Kiowski W, Julius S (1977 b) Effect of beta-adrenoceptor antagonists on baroreceptor reflex sensitivity in hypertension Clin Pharmacol Ther 22: 293–298.Google Scholar
- 22.Sleight P, West MJ (1975) The effects of clonidine on the baroreflex arc in man. In: Davies DS, Reid JL (eds), Central action of drugs in blood pressure regulation. Pitman Medical, Tunbridge, Wells 291–299.Google Scholar
- 24.Sleight P, Gribbin B, Pickering TG (1979) Baroreflex sensitivity in normal and hypertensive man: the effect of beta adrenergic blockade on reflex sensitivity. Post Grad Med J 47: 79–81.Google Scholar
- 26.Takeshita et al. (1975) Circulation 51: 739.Google Scholar