Baroreceptor sensitivity in prehypertensive young adults.

Abstract

Decreased baroreceptor reflex sensitivity has been implicated in the pathogenesis of hypertension. The purpose of this study is to determine if alterations of baroreceptor function precede the development of hypertension in humans. Baroreceptor function was evaluated in 13 young adult white men with relatively high blood pressures sustained for 12 to 15 years and 12 age-matched men with sustained relatively low blood pressures. High pressure baroreceptor activity was evaluated by measuring change in pulse interval in response to decreases and increases of arterial pressure, induced by graded infusions of nitroprusside and angiotensin II, respectively. In response to both agents, baroreceptor slopes did not differ in the high and low blood pressure groups. Plasma norepinephrine also increased similarly in both blood pressure groups in response to nitroprusside. To study low-pressure baroreceptor function, responses to graded levels of lower-body negative pressure (LBNP) were measured. Comparing both blood pressure groups, there were similar increases of heart rate, total peripheral resistance, and plasma norepinephrine in response to LBNP. Both blood pressure groups also had similar increases of heart rate and blood pressure in response to isometric (handgrip) exercise. Thus, high-pressure and low-pressure baroreceptor function is not altered in prehypertensive young adults. However, continued follow-up will be required to determine if these individuals with sustained relatively high blood pressures are truly prehypertensive. (Hypertension 1989;13:878-883) A lterations of neural activity have been implicated in the pathogenesis of both clinical and experimental hypertension. 1 -3 Plasma catecholamine concentrations tend to be elevated in young, hypertensive humans, and sympathetic nervous system activity is increased in several models of hypertension studied after the development of hypertension.1 -2 In response to acute elevations of arterial pressure, baroreceptor reflex sensitivity is decreased in both hypertensive animals and humans.14 Furthermore, baroreceptor reflex control of heart rate and vascular resistance is impaired in the prehypertensive Dahl salt-sensitive rat, and it has been suggested that this impairment contributes to the rat's propensity to develop hypertension. 5 -8 Cardiopulmonary baroreceptor reflex sensitivity is also decreased in the prehypertensive Dahl saltsensitive rat, as evidenced by a reduced capacity to inhibit efferent sympathetic nerve activity in response to plasma volume expansion. 9 The current study is designed to evaluate the hypothesis that alterations of neural activity precede the development of hypertension in humans.In 1973, we initially measured blood pressure in all high school students residing in Bourbon County, Kentucky («=l,140). Standardized measurements of blood pressure were repeated in these same individuals in 1978, 1981, and 1985. In this population, there were highly significant correlations between repeated measurements of blood pressure over time, and ...

Neurohumoral and Metabolic Effects of Short-Term Dietary NaCl Restriction in Men Relationship to Salt-Sensitivity Status

“…7 Kotchen and colleagues reported significantly greater supine and seated diastolic blood pressure in 12 normotensive men during a low (10 mEq/day) ν a high (250/mEq/day) sodium diet. 20 Another report confirms the observation of higher seated diastolic blood pressure during a low ν high salt diet and extends these observa tions to both black and white hypertensive and normo tensive subjects. 21 Therefore, data from our study and from the other investigations cited suggest that the blood pressure re sponse to dietary NaCl restriction is not uniformly a depressor response.…”

Sympathoexcitation and impaired arterial baroreflex sensitivity are linked to vascular inflammation in individuals with elevated resting blood pressure

“…Our results, however, contrast with the findings of Kotchen et al. () who reported no differences in cardiovagal BRS in a cohort of 13 Caucasian males with prehypertension compared to 12 matched normotensive controls. This difference might be due in part to the fact that Kotchen et al.…”

“…Experimental studies (Gordon and Mark ) have reported impaired baroreceptor discharge in prehypertensive Dahl salt‐sensitive rats compared to normotensive rats (Gordon and Mark ), while human studies have shown mixed results (Kotchen et al. ; Rea and Hamdan ; Pal et al. ), likely due in part to differences in technique and study populations including racial differences.…”

Sodium restriction and insulin resistance: A review of 23 clinical trials

“…In other words, 44% of the men were salt sensitive but 41% were reverse responders, who had higher blood pressure on the low-salt diet. The authors went on to note, '… a study of hypertensive patients by Longworth et 32 Another report confirms the observation of higher seated diastolic blood pressure during a low v high-salt diet and extends these observations to both black and white hypertensive and normotensive [participants] 33 '. 22 All of these studies indicate that a large percentage of the population does not have a clinically meaningful drop in blood pressure with salt restriction and that in many cases there can even be an increase in blood pressure.…”