Hypertension following denervation of aortic baroreceptors in unanesthetized dogs.

Abstract

SUMMARY After cervical aortic nerve section, mean arterial pressure in the unanesthetized dog increased by an average of 7.4 mm Hg. Following a more extensive denervation of aortic arch receptors by section of intrathoracic vagal branches, arterial pressure increased by 16.7 mm Hg. The above changes were seen in the stable state after the effects of surgery had disappeared. In both cases carotid baroreceptors were functional. After administration of nitroglycerin and phenylephrine subsequent to either denervation procedure, blood pressure changes were larger and heart rate responses were smaller than in the control state. The unanesthetized dog regulates mean arterial pressure at a higherthan-normal pressure after aortic baroreceptor denervation. Reflexes from the aortic baroreceptors continuously participate in the normal control of mean arterial pressure. Section of the cervical aortic nerves only partially denervates aortic baroreceptors. Our findings may be relevant to human essential hypertension. Ore Res 45: 26-34, 1979

Relative contribution of aortic and carotid baroreflexes to heart rate control in man during steady state and dynamic increases in arterial pressure.

“…Vatner et al (1) suggested from studies in awake dogs that the aortic baroreceptors were more effective than the carotid baroreceptors in controlling heart rate. Similar findings in the dog were reported by Ito and Scher (2,3) in which chronic denervation experiments suggested that reflex heart rate responses are impaired to a greater extent by aortic baroreflex denervation than by carotid denervation. In contrast, Guo et al (4) have shown the carotid and aortic baroreceptors exert similar degrees of vagally mediated heart rate control in anesthetized rabbits during phenylephrine (PE)-induced' hypertension.…”

“…Fig. 3 and Table I summarize the responses of subjects [1][2][3][4][5][6][7][8][9][10] Table I), which was associated with a prolongation of HI from 1,068±58 to 1,297±69 ms (P < 0.05). This was an average gain in HI of 27.7 ms/mmHg increase in MAP.…”

“…Figure 6. Baroreflex slope during bolus PE alone and during bolus PE with superimposed dynamic NP (subjects 1 [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. The slope of the arterial baroreflex control of HI during PE bolus plus superimposed dynamic NP application (aortic baroreflex activation alone) was reduced by 30% over that during bolus PE alone (aortic and carotid baroreflex activation).…”

Arterial Pressure and Its Variability in Conscious Rabbits at Different Ages

“…SD or V is one index of stability of AP. Since the value of SD was increased by sectioning afferent nerves from the baroreceptors [3,12,13,17], and decreased in the normotensive pressure range [15,17], the increase in SD represents reduced control ability of the baroreflex system. This accords well with the fact that an open-loop gain, a homeostatic index of the baroreflex system, was decreased by severing the carotid sinus, aortic or vagus nerves [10,11].…”

“…Therefore, we can conclude that the overall control ability of the rapidly acting AP control system is not affected by aging within the range from 6 to 30 months. Distribution pattern of histogram has often been employed for estimation of variability of AP [3,12,13,15]. Distribution became wide after the baroreceptors had been denervated [3,12,131, whereas narrow distribution and an exaggerated mode imply increased control ability of the baroreflex system.…”