Nucleus Tractus Solitarii (NTS): Does It Mask the Interaction of Blood Pressure and Thermal Energetics?
It is generally accepted that sino-aortic (SA) baroreceptor reflexes are “reset” in both experimental and clinical forms of arterial hypertension. In the unanesthetized endotherm these reflexes tonically inhibit medullary vasomotor centres whose function is most often considered in the context of circulatory homeostasis: Elevation of systemic arterial blood pressure (BP) activates SA mechanoreceptors and elicits neurogenically mediated compensatory reductions in heart rate and peripheral vasomotor tone (1). It is less well acknowledged that circulation is quite responsive to even mild thermal demands and controls thermogenic effector systems. In a cool (10–15°C) environment most normoten-sive endotherms, including humans, exhibit tonic increases in cardiac output, stroke volume, and mean aortic BP that are associated with proportionally greater elevations in total body oxygen consumption (2–8). Such cardiovascular responses are part of a more general hemodynamic adjustment designed to coregulate the nutritive and heat dissipating functions of circulation.
KeywordsBrown Adipose Tissue Rectal Temperature Nucleus Tractus Solitarii Blood Pressure Responsiveness Systemic Arterial Blood Pressure
Unable to display preview. Download preview PDF.
- 1.Korner P I: Integrative neural cardiovascular control. Physiol Rev (51): 312–367, 1966.Google Scholar
- 2.Budd G M, Warhaft N: Body temperature, shivering, blood pressure and heart rate during standard cold stress in Australia and Antarctica. J Physiol (London) (186): 216–232, 1966.Google Scholar
- 4.Popovic V, Kent K, Mojovic N, Mojovic B, Hart J S: Effect of exercise and cold on cardiac output in warm- and cold- acclimated rats. Federation Proc (28): 1138–1142, 1969.Google Scholar
- 5.Alexander G, Williams D: Cardiovascular function in young lambs during sumnit metabolism. J Physiol (London) (208): 65–83, 1970.Google Scholar
- 7.Alexander G, Bell A W, Setchell B P: Regional distribution of cardiac output in young lambs: effect of cold exposure and treatment with catecholamines. J Physiol (London) (220): 511–528, 1972.Google Scholar
- 9.Hissa R, Rautenberg W. The influence of centrally applied noradrenaline on shivering and body temperature in the pigeon. J Physiol (London) (238): 421–435, 1974.Google Scholar
- 12.Marshall H W, Stoner H B. Catecholamine rgic a-receptors and shivering in the rat. J Physiol (London) (292): 27–34, 1979.Google Scholar
- 17.Koch E. Irradiation der pressorezeptorishen KreisLaufreflexe auf das animale nervensystem. Z KriesLaufforsch (24): 251–258, 1932.Google Scholar
- 18.Heymans C, Neil E. Reflexogenic areas of the cardiovascular system. Little Brown, Boston, 1959.Google Scholar
- 19.Iggo A, Vogt M. The mechanism of adrenaline induced inhibition of sympathetic preganglionic activity. J Physiol (London) (161): 62–72, 1962Google Scholar
- 21.Buchholz R A, Nathan M A: Chronic lability of the arterial blood pressure produced by electrolytic lesions of the nucleus tractus solitarii in the rat. Circ Pas (54): 227–238, 1984.Google Scholar
- 22.Cherniak N S, Longobardo J A: Localization of central cardiovascular and acid-base control mechanisms in the lower brainstem of the cat and rat. Physiol Rev (50): 196–212, 1970.Google Scholar
- 23.Palkovits M, Zaborszky L: Neuroanatomy of central cardiovascular control. Nucleus tractus solitarii: afferent and efferent connections in relation to the baroreceptor reflex arch. In: De Jong W, Provost A P, Shapiro A P (Eds) Hypertension and brain mechanisms. Elsevier Scientific Publ, New York, 1977, pp 9–34.CrossRefGoogle Scholar
- 24.Paxinos G, Watson C: The rat brain in stereotaxic coordinates. Academic Press, 1982.Google Scholar
- 27.Mott J C: The effects of baroreceptor and chemoreceptor stimulation on shivering. J Physiol (London) (166): 563–586, 1963.Google Scholar
- 32.Powell L B: Human cardiovascular adjustments to exercise and thermal stress. Physiol Rev (54): 75–159, 1974.Google Scholar