Effect of Age on the Responsiveness of Vascular α-Adrenoceptors in Man

Elliott, Henry L.; Sumner, D. J.; McLean, Kathleen; Reid, John L.

doi:10.1097/00005344-198205000-00008

Cited by 79 publications

(39 citation statements)

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“…15 In humans, adult aging is also associated with selective changes in arterial BP control as well as responsiveness to vasoactive agents. 7,12,14,21,27,28 Many patients with autonomic-cardiovascular disorders are middleaged and older, suggesting that their reduced baroreflex buffering and altered responsiveness to vasoactive drugs may be mediated by the combined effects of aging and disease. This cannot be determined, however, because there is presently no information on possible changes in baroreflex buffering with healthy (physiological) aging in humans.…”

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confidence: 99%

Baroreflex Buffering Is Reduced With Age in Healthy Men

et al. 2003

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Baroreflex Buffering Is Reduced With Age in Healthy Men

et al. 2003

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“…13,17,18 Although studies consistently demonstrate that PE infusions lead to increased BP, the magnitude of this effect appears to be influenced by demographic factors, including hypertension status, age, gender, and ethnicity. 18,19 Ethnic and racial differences in pressor sensitivity to PE have been well-documented. Several studies have found that blacks have greater pressor responses to alpha agonists than whites.…”

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Job Strain, Ethnicity, and Sympathetic Nervous System Activity

et al. 2004

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Abstract-Several studies have demonstrated that blacks have heightened pressor sensitivity in response to the ␣-agonist, phenylephrine. However, studies examining whether psychosocial factors contribute to this difference are scarce. We examined the effects of job strain on pressor sensitivity in 76 whites and 46 blacks who were enrolled in a study of stress, sleep, and blood pressure. Responses to phenylephrine were examined at an inpatient clinical research center. After a 3-minute baseline period, a 100-microgram phenylephrine bolus was administered to participants intravenously. To measure catecholamines, 24-hour urine samples were also collected from participants. There was a significant relationship between job strain and pressor sensitivity, such that individuals with low decisional control and high job demands experienced a greater increase in diastolic pressure after receiving phenylephrine. Low decisional control was also associated with decreased baroreflex sensitivity. There was an interaction between ethnicity and job control on blood pressure responses to phenylephrine and on 24-hour urinary norepinephrine levels. Blacks who perceived less control experienced a greater increase in diastolic pressure after receiving phenylephrine and had elevated norepinephrine levels. These findings suggest possible mechanisms by which job strain may be associated with cardiovascular disease.

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“…There was a nonsignificant difference in increase of MABP between the Sherpas (24Ϯ6 mm Hg; 29Ϯ7%) compared with the newcomers to the altitude (20Ϯ5 mm Hg; 21Ϯ6%) and the sea-level subjects (19Ϯ2 mm Hg; 23Ϯ4%). After extrapolation from the phenylephrine log dose-pressor response curve, as determined by Elliott and coworkers, 11 we calculated that for a 20-mm-Hg increase in MABP, the Sherpa group should have a phenylephrine infusion dose of approximately 2.9 g ⅐ …”

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Cerebral Autoregulation in Subjects Adapted and Not Adapted to High Altitude

Jansen

Krins

Basnyat

et al. 2000

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Background and Purpose-Impaired cerebral autoregulation (CA) from high-altitude hypoxia may cause high-altitude cerebral edema in newcomers to a higher altitude. Furthermore, it is assumed that high-altitude natives have preserved CA. However, cerebral autoregulation has not been studied at altitude. Methods-We studied CA in 10 subjects at sea level and in 9 Sherpas and 10 newcomers at an altitude of 4243 m by evaluating the effect of an increase of mean arterial blood pressure (MABP) with phenylephrine infusion on the blood flow velocity in the middle cerebral artery (Vmca), using transcranial Doppler. Theoretically, no change of Vmca in response to an increase in MABP would imply perfect autoregulation. Complete loss of autoregulation is present if Vmca changes proportionally with changes of MABP. Results-In the sea-level group, at a relative MABP increase of 23Ϯ4% during phenylephrine infusion, relative Vmca did not change essentially from baseline Vmca (2Ϯ7%, Pϭ0.36), which indicated intact autoregulation. In the Sherpa group, at a relative MABP increase of 29Ϯ7%, there was a uniform and significant increase of Vmca of 24Ϯ9% (PϽ0.0001) from baseline Vmca, which indicated loss of autoregulation. The newcomers showed large variations of Vmca in response to a relative MABP increase of 21Ϯ6%. Five subjects showed increases of Vmca of 22% to 35%, and 2 subjects showed decreases of Vmca of 21% and 23%. Conclusions-All Sherpas and the majority of the newcomers showed impaired CA. It indicates that an intact autoregulatory response to changes in blood pressure is probably not a hallmark of the normal human cerebral vasculature at altitude and that impaired CA does not play a major role in the occurrence of cerebral edema in newcomers to the altitude.

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Effect of Age on the Responsiveness of Vascular α-Adrenoceptors in Man

Cited by 79 publications

References 0 publications

Baroreflex Buffering Is Reduced With Age in Healthy Men

Baroreflex Buffering Is Reduced With Age in Healthy Men

Job Strain, Ethnicity, and Sympathetic Nervous System Activity

Cerebral Autoregulation in Subjects Adapted and Not Adapted to High Altitude

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