The Importance of Adaptive Changes in Vascular Design for the Establishment and Maintenance of Primary Hypertension, as Studied in Man and in Spontaneously Hypertensive Rat

Folkow, Björn; Hallbäck, Margareta; Lundgren, Yen; Sivertsson, Ramon; Weiss, Lilian

doi:10.1007/978-3-642-65441-1_23

Cited by 338 publications

(256 citation statements)

References 18 publications

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“…It is possible that the depressor response in SHRSP is caused by structural changes of the blood vessels in hypertension. 24 This possibility is unlikely, however, because other studies that examined the effect of microinjections of kynurenic acid (a glutamate receptor antagonist), 25 muscimol, 26 or glycine 27 into the RVLM of SHR or WKY reported specific responses evoked by several agonists or antagonists. Importantly, tempol reduced MAP and HR only in SHRSP.…”

Section: Discussionmentioning

confidence: 99%

Increased Reactive Oxygen Species in Rostral Ventrolateral Medulla Contribute to Neural Mechanisms of Hypertension in Stroke-Prone Spontaneously Hypertensive Rats

et al. 2004

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Background-Oxidative stress increases in hypertension. The aim of this study was to determine whether reactive oxygen species (ROS) are increased in the rostral ventrolateral medulla (RVLM) in the brainstem, where the vasomotor center is located, in stroke-prone spontaneously hypertensive rats (SHRSP), and, if so, to determine whether the increased ROS contribute to neural mechanisms of hypertension in SHRSP. Methods and Results-We measured ROS levels in the RVLM of SHRSP and compared them with those in Wistar-Kyoto rats (WKY). Thiobarbituric acid-reactive substances were increased in SHRSP compared with WKY. ROS were measured by electron spin resonance (ESR) spectroscopy. The ESR signal decay rate in the RVLM of SHRSP was significantly increased compared with that in WKY, and this increase was abolished by dimethylthiourea (a hydroxyl radical scavenger). The increased ESR signal decay rate was reduced to the same extent in the presence of desferrioxamine, catalase, and Tiron, indicating that hydroxyl radicals are derived from superoxide anions and hydrogen peroxide. In addition, total superoxide dismutase (SOD) activity in the RVLM was decreased in SHRSP compared with WKY. Furthermore, bilateral microinjection of tempol into the RVLM decreased blood pressure in SHRSP but not in WKY, and MnSOD overexpression in the RVLM of SHRSP decreased blood pressure and inhibited sympathetic nerve activity. Conclusions-These results suggest that superoxide anions in the RVLM, which generate hydroxyl radicals, are increased in SHRSP and contribute to the neural mechanisms of hypertension in SHRSP.

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Section: Discussionmentioning

confidence: 99%

Increased Reactive Oxygen Species in Rostral Ventrolateral Medulla Contribute to Neural Mechanisms of Hypertension in Stroke-Prone Spontaneously Hypertensive Rats

et al. 2004

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“…This does not apply to BP change since subjects with elevated resting SBP have on the average higher ASBP. In some hemodynamic studies, 14 " 16 it has been demonstrated that subjects with elevated baseline vascular resistance present a further exaggerated increase on various sympathetic stimuli. This fact is usually related to structural changes of the vascular bed of subjects with chronic BP elevation, i.e., hypertrophy of the vessel wall, and in these subjects, physical exercise would trigger an excessive rise in peripheral vascular resistance.…”

Section: Discussionmentioning

confidence: 99%

Prognostic significance of exercise blood pressure and heart rate in middle-aged men.

1992

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Systolic blood pressure and heart rate measured at rest and during a standardized exercise test were analyzed in the cohort of middle-aged male employees followed-up an average of 17 years in the Paris Prospective Study L The population sample selected for the analysis included 4,907 men who completed at least 5 minutes of bicycle ergometry, who had no heart disease at entry, and whose resting blood pressure was s 180/105 nun Hg. Exercise-induced increase in systolic blood pressure was positively correlated with resting systolic blood pressure (r=0.104, p<0.0001), whereas the correlation of exerciseinduced heart rate increase with resting heart rate was negative (r=-0.169, p<0.0001). Using Cox regression analysis with the inclusion of resting systolic blood pressure and heart rate; exercise-induced elevations of systolic blood pressure and heart rate; and controlling for age, smoking, total cholesterol, body mass index, electrical left ventricular hypertrophy, and sports activities, cardiovascular mortality was found to be associated with the systolic blood pressure increase (p<0.05), whereas no association with resting systolic blood pressure was found. Total mortality was predicted by resting systolic blood pressure and its elevation (p<0.01 for both) and by resting heart rate (p<0.0001). The heart rate increase did not contribute to death prediction. In conclusion, the magnitude of the exercise-induced increase of systolic blood pressure, but not of heart rate, may represent a risk factor for death from cardiovascular as well as noncardiovascular causes, independently of resting blood pressure and heart rate. (Hypertension 1992^0-333-339) KEY WORDS • blood pressure • heart rate • exercise test • prospective studies • mortality A rterial blood pressure (BP) is a strong determi-/ \ nant of life prognosis, and cardiovascular A. A . (CV) as well as total mortality are definitely higher in subjects who are classified as hypertensive according to BP measurement at rest. Although relatively less attention has been drawn to heart rate (HR) level, it was also found to be associated with mortality.1 There is a logical tendency to measure these two parameters in basal conditions at rest to achieve maximal standardization; however, it does not imply that this way of assessing BP and pulse rate is the most predictive of individual risk. Exercise testing yields important 'information about circulatory status and perhaps about life prognosis since it may reflect, with other factors, physical fitness and presence or absence of coronary atherosclerosis.Exercise tests are widely used in patients in whom coronary heart disease is suspected, and the strong predictive value of pathological electrocardiographic changes, mainly of the ST segment, has been confirmed several times.2 -4 Several authors have studied BP and HR changes on physical load in various populations 4 -3 ; however, the prognostic value of these parameters in an intact population remains unestablished. Recently, Fagard et al 6 published interesting results on...

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“…Folkow et al, 29 for example, have argued that structural changes in the vessels, involving an increased wall-tolumen ratio, account for the greater total peripheral resistance 30 in SHRs. Under such conditions, the same amount of neural discharge would produce a greater vascular response.…”

Section: Behavioral Specificity Of Cardiovascular Hyperreactivity Sugmentioning

confidence: 99%

Behaviorally selective cardiovascular hyperreactivity in spontaneously hypertensive rats. Evidence for hypoemotionality and enhanced appetitive motivation.

LeDoux¹,

Sakaguchi²,

Reis³

1982

Hypertension

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SUMMARY Spontaneously hypertensive rats (SHRs) and Wistar Kyoto controls (VVKYs) were chronically instrumented for computer-assisted recording of arterial pressure (AP) and heart rate (HR) and examined during classically conditioned emotional (fear) reactions or during the performance of a repertoire of natural behaviors, including eating, drinking, grooming, exploring, and resting. The purpose of the study was to determine whether exaggerated cardiovascular reactivity in SHRs during aversive stimulation: 1) can be coupled to stimuli that before conditioning elicited negligible changes in AP and HR; 2) is accompanied by a proportionately enhanced level of emotional arousal; and 3) is specific to aversive emotional arousal or is also present during natural behaviors. The conditioned blood pressure response (in mm Hg) was greater (p < 0.01) in SHRs (peak response, 20 ± 3) than in WKYs (peak response, 7 ± 1). While the conditioned pressure response was accompanied by bradycardia in WKYs (peak response, -1 3 ± 5 bpm), tachycardia was present in SHRs (peak response, 17 ± 7 bpm). Behavioral tests indicated reduced emotional reactions in SHRs: SHRs showed less (p < 0.05) drink suppression (75 ± 17 sec) than WKYs (111 ± 10 sec) and SHRs showed less (p < 0.01) suppression of exploratory activity (201 ± 40 sec) than WKYs (499 ± 70) in the presence of the conditioned emotional stimulus. The magnitude of blood pressure changes (in mm Hg) above resting baseline was not different in SHRs and WKYs during eating (SHR, 32 ± 3; WKY, 28 ± 2), grooming (SHR, 17 ± 3; WKY, 14 ± 2), or exploring (SHR, 17 ± 2; WKY, 18 ± 2), but was greater (p < 0.01) during drinking in SHRs (48 ± 4) than in WKYs (32 ± 2). The amount of time (sec) spent grooming (SHR, 55 ± 23; WKY, 38 ± 15) and exploring (SHR, 187 ± 33; WKY, 165 ± 42) did not differ between the strains, but SHRs spent more time (p < 0.01) eating (SHR, 1103 ± 88; WKY, 800 ± 114) and drinking (SHR, 119 ± 18; WKY, 32 ± 12). These findings demonstrate that: 1) exaggerated cardiovascular reactivity in SHRs is readily coupled through conditioning to otherwise benign stimuli; 2) conditioned cardiovascular hyperreactivity is accompanied by a reduced not an enhanced level of conditioned emotional arousal; 3) cardiovascular hyperreactivity is not specific to aversive arousal but is nevertheless a behaviorally-specific mode of response; and 4) SHRs and WKYs differ in the performance of natural as well as emotional behaviors. (Hypertension 4: 853-863, 1982) KEY WORDS • blood pressure • natural behavior • conditioned emotional responses • spontaneously hypertensive rats • classical conditioning A RTERIAL pressure (AP) changes associated with aversive emotional arousal are exaggerated in spontaneously hypertensive rats (SHRs) when compared with strain-matched WistarKyoto controls (WKYs): during the acute or chronic presentation of aversive stimuli, such as electric foot-

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The Importance of Adaptive Changes in Vascular Design for the Establishment and Maintenance of Primary Hypertension, as Studied in Man and in Spontaneously Hypertensive Rat

Cited by 338 publications

References 18 publications

Increased Reactive Oxygen Species in Rostral Ventrolateral Medulla Contribute to Neural Mechanisms of Hypertension in Stroke-Prone Spontaneously Hypertensive Rats

Increased Reactive Oxygen Species in Rostral Ventrolateral Medulla Contribute to Neural Mechanisms of Hypertension in Stroke-Prone Spontaneously Hypertensive Rats

Prognostic significance of exercise blood pressure and heart rate in middle-aged men.

Behaviorally selective cardiovascular hyperreactivity in spontaneously hypertensive rats. Evidence for hypoemotionality and enhanced appetitive motivation.

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