Neuroendocrine and cardiovascular stress reactivity in middle-aged normotensive adults with parental history of cardiovascular disease

Sympathetic neural reactivity to mental stress in offspring of hypertensive parents: 20 years revisited

A number of recent studies have highlighted large interindividual variability of muscle sympathetic nerve activity (MSNA) responsiveness to mental stress in humans. The purpose of this study was to examine blood pressure (BP) and MSNA responsiveness to mental stress in a large and generalizable cohort of young adults with and without family history of hypertension (FHH). We hypothesized that subjects with FHH would demonstrate greater sympathoexcitation to mental stress than subjects without FHH. A total of 87 subjects (55 men and 32 women, 18-40 yr of age) from recently published (n = 45) and ongoing (n = 42) studies were examined; 57 subjects (19 with FHH and 38 without FHH) had complete MSNA recordings at baseline. Heart rate (HR), BP, and MSNA were recorded during 5 min of supine rest and 5 min of mental stress (mental arithmetic). Resting MSNA and HR were not statistically different between subjects with and without FHH (P > 0.05), whereas resting mean arterial pressure was higher in subjects with FHH (86 ± 2 vs. 80 ± 1 mmHg, P < 0.05). Mental stress increased MSNA in subjects with FHH (Δ5 ± 1 bursts/min), but not in subjects without FHH [Δ1 ± 1 burst/min, P < 0.01 (time × group)]. Mental stress increased mean arterial pressure (Δ12 ± 1 and Δ10 ± 1 mmHg, P < 0.001) and HR (Δ19 ± 2 and Δ16 ± 2 beats/min, P < 0.001) in subjects with and without FHH, but these increases were not different between groups [P ≥ 0.05 (time × group)]. MSNA and BP reactivity to mental stress were not correlated in either group. In conclusion, FHH was associated with heightened MSNA reactivity to mental stress, despite a dissociation between MSNA and BP responsiveness.

Differential circadian catecholamine and cortisol responses between healthy women with and without a parental history of hypertension

OBJECTIVES

Previous studies suggest that otherwise healthy individuals who have a parental history of hypertension (PH+) have an accentuated reactive rise in catecholamines and cortisol to laboratory stressors as well as elevated plasma levels when compared with those with no parental history (PH-); however, few, if any, studies have evaluated whether parental history affects the responses of these hormones to changing environmental circumstances in everyday life. The purpose of this study was to compare urinary catecholamine (epinephrine and norepinephrine) and cortisol excretion and ambulatory blood pressures (BPs) across three daily microenvironments between women with and without a parental history of hypertension.

METHODS

The women in the study (PH+, N = 62, age = 35.2 ± 9.1; PH-, N = 72, age = 33.8 ± 10.0) worked in clerical, technical, or professional positions at a major medical center in New York City. Urinary hormone excretion rates and ambulatory BP were measured across three daily microenvironments: work (11 am to 3 p.m.), home (approximately 6 p.m. to 10 p.m.), and during sleep (approximately 10 p.m. to 6 a.m.). History group comparisons by microenvironment were made using repeated-measures ANCOVA and ANOVA analyses.

RESULTS

The results show that epinephrine excretion among PH+ women was 36% higher than PH- women (P < 0.008) over the entire day and that nocturnal cortisol excretion was also greater among PH+ women (P < 0.045). PH+ women also had statistically significantly higher systolic (4 mm Hg higher; P < 0.01) and diastolic (2 mm Hg higher, P < 0.03) BP when compared with PH- women across all daily microenvironments.

CONCLUSION

These findings suggest that there may be genetically linked mechanisms which elevate tonic epinephrine levels and nocturnal cortisol levels that contribute to elevating circadian BP.

Salivary alpha-amylase as a non-invasive biomarker for the sympathetic nervous system: current state of research

Development of new biomarkers is a constantly evolving field of research endeavor in psychoneuroendocrinology. Salivary biomarkers have received special attention since they are readily accessible and easily obtained. Salivary alpha-amylase (sAA) has been proposed as a sensitive biomarker for stress-related changes in the body that reflect the activity of the sympathetic nervous system (SNS), and a growing body of research is accumulating to support the validity and reliability of this parameter. However, questions remain to be answered before sAA can be accepted as an index of SNS activity. This review describes sAA as an emerging biomarker for stress and provides an overview of the current literature on stress-related alterations in sAA. It critically discusses how sAA might reflect changes in the autonomic nervous system. Finally, current and future fields for the application of sAA measurement are outlined.

Elevated levels of circulating cortisol in young normotensive adult men with a family history of hypertension

1. Differences in blood lipids, glucose, insulin, amylin, adrenocorticotropic hormone (ACTH), cortisol, aldosterone, angiotensin II, metabolites of nitric oxide (nitrate, nitrite), asymmetric dimethyl arginine, endothelial leucocyte adhesion molecule-1, vascular cell adhesion molecule-1, C-reactive protein, homocysteine and oxidative status (urate, vitamin A, vitamin E, beta-carotene and total anti-oxidant capacity) were investigated in men (aged 18-25 years) with (+) or without (-) a family history (FH) of hypertension. 2. In the present study, FH+ was defined as having at least one parent or grandparent taking medication for hypertension. Blood (60 mL) was sampled (0800-1000 hours) from a cannulated forearm vein after an overnight fast and 24 h abstinence from caffeine-containing products and alcohol. 3. Comparing FH+ with FH-, systolic blood pressure (124 +/- 1 vs 117 + 3 mmHg, respectively; n = 50 and 14, respectively; P < 0.05) and plasma cortisol (377 +/- 23 vs 298 +/- 24 nmol/L, respectively; n = 43 and 12, respectively; P < 0.05) were found to be significantly higher in the former group. 4. No significant difference was found between the two groups for body mass index, resting heart rate, diastolic and mean blood pressures or any of the biochemical measures studied. 5. A significant correlation was found between cortisol and ACTH (r = 0.73). No correlation was found between cortisol and any other parameter measured. 6. These data indicate that elevated cortisol levels are characteristic of young lean normotensive FH+ men. The future impact of this on their vascular health and hypertension remains to be determined.

Low social support and poor emotional regulation are associated with increased stress hormone reactivity to mental stress in systemic hypertension

CONTEXT

There is strong evidence for a physiological hyperreactivity to stress in systemic hypertension, but data on associated or potentially moderating psychological factors are scarce.

OBJECTIVE

The objective of the study was to identify psychological correlates of physiological stress reactivity in systemic hypertension.

DESIGN

This was a cross-sectional, quasi-experimentally controlled study. Study participants underwent an acute standardized psychosocial stress task combining public speaking and mental arithmetic in front of an audience.

SETTING

The study was conducted in the population in the state of Zurich, Switzerland.

SUBJECTS

Subjects included 22 hypertensive and 26 normotensive men (mean +/- sem 44 +/- 2 yr).

MAIN OUTCOME MEASURES

We assessed the psychological measures social support, emotional regulation, and cognitive appraisal of the stressful situation. Moreover, we measured salivary cortisol and plasma epinephrine and norepinephrine before and after stress and several times up to 60 min thereafter as well as blood pressure and heart rate.

RESULTS

We found poorer hedonistic emotional regulation (HER) and lower perceived social support in hypertensives, compared with normotensives (P < 0.01). Compared with normotensives, hypertensives showed higher cortisol, epinephrine, and norepinephrine secretions after stress (P < 0.038) as well as higher systolic and diastolic blood pressure (P < 0.001). Cortisol reactivity and norepinephrine secretion were highest in hypertensive men with low HER (P < 0.05). In contrast, hypertensives with high HER did not significantly differ from normotensives in both cortisol and norepinephrine secretion after stress. Epinephrine secretion was highest in hypertensives with low social support but was not different between hypertensives with high social support and normotensives.

CONCLUSIONS

The findings suggest that both low social support and low HER are associated with elevated stress hormone reactivity in systemic hypertension.

Adrenocortical and nociceptive responses to opioid blockade in hypertension-prone men and women

OBJECTIVE

Attenuated pain sensitivity and exaggerated adrenocortical stress reactivity have been documented in individuals at high risk for hypertension. The endogenous opioid system may play a role in these response alterations. We compared adrenocortical and nociceptive responses to opioid blockade using naltrexone in hypertension-prone men and women.

METHODS

Ninety-nine participants completed two sessions during which a placebo or 50 mg naltrexone was administered using a double-blind, counterbalanced design. Participants rated their pain and completed the McGill Pain Questionnaire (MPQ) after three assessments of the nociceptive flexion reflex and after assessment of nociceptive pain threshold and tolerance. Saliva samples were obtained throughout the sessions.

RESULTS

Salivary cortisol levels increased after pain assessment after the ingestion of naltrexone, but not after placebo, with the low-risk group exhibiting an earlier peak of cortisol response. Participants reported greater pain ratings and higher MPQ scores in the naltrexone versus placebo condition, and these effects were more pronounced in women. Pain threshold and tolerance were higher among high-risk men relative to low-risk men.

CONCLUSIONS

The results are consistent with the inhibitory effects of the endogenous opioids on cortisol response and suggest an altered response timeline among hypertension-prone individuals. The results demonstrate that hypoalgesia may be a marker of hypertension risk in men but not in women.

The importance of examining blood pressure reactivity and recovery in anger provocation research

OBJECTIVE

We investigated the moderating relationship of hostility on emotional and physiological arousal due to acute anger provocation; stress reactivity and recovery were measured.

METHOD

Forty-five participants completed a measure of trait hostility (CMHQ) and performed a mental arithmetic (serial 7s) task while receiving scripted comments at set intervals designed to provoke anger (harassment). The impact of trait hostility (high, medium or low) on arousal and recovery was examined.

RESULTS

Participants low in self-reported hostility showed greater HR reactivity to the task but recovered quickly. Participants high in hostility showed noticeably slower recovery in SBP maintained after task completion.

CONCLUSIONS

The findings underscore the importance of examining both reactivity and recovery data in anger provocation research because the apparent influence of trait hostility on cardiovascular functioning would have been missed if recovery had not been systematically studied.

Cardiovascular reactivity and family history of hypertension: A meta-analysis

A regression-based meta-analysis examined the degree to which the effects of a family history of hypertension on cardiovascular reactivity are moderated by the magnitude of cardiovascular responses elicited in challenge/task conditions. Mean change scores for negative family history groups were regressed on mean change scores for positive family history groups. The slopes of separate regression lines obtained for systolic and diastolic blood pressure and heart rate were significantly less than 1.0 and the y-intercepts for these regression lines were significantly greater than zero. This pattern indicates that family history differences in cardiovascular reactivity to stress are greatest in situations that elicit the smallest baseline-stressor change scores in non-family-history groups.

Enhanced adrenocortical responses to stress in hypertension-prone men and women

Hypertension risk may be associated with increased adrenocortical activity, but the extent to which this enhanced activation differs between men and women at rest and in response to psychological stress is not known. This study examined gender differences in adrenocortical responses to an extended public-speaking stressor in persons at high (resting systolic blood pressure > median; n = 21) or low risk (negative parental history and < or = median systolic blood pressure; n = 26). Salivary cortisol levels were assessed at rest and in response to public speaking in a repeated measure design on two test sessions held on separate days. Heart rate, systolic blood pressure, and diastolic blood pressure were obtained at 3-min intervals before, during, and after the task. High-risk participants showed greater cortisol, blood pressures, and heart rate responses to the public-speaking stressor than the low-risk group (ps < .01). Men showed greater cortisol concentrations than women (p < .05), independent of hypertension risk status. Cardiovascular measures during the acute stressor predicted subsequent cortisol production, but only in the high-risk group. Results suggest that hypertension risk is associated with enhanced physiological reactivity across sympathetic and adrenocortical systems, supporting the possibility that this exaggerated reactivity may represent a marker of risk in hypertension-prone men and women.

Love, marriage, and divorce: newlyweds' stress hormones foreshadow relationship changes

Neuroendocrine function, assessed in 90 couples during their first year of marriage (Time 1), was related to marital dissolution and satisfaction 10 years later. Compared to those who remained married, epinephrine levels of divorced couples were 34% higher during a Time 1 conflict discussion, 22% higher throughout the day, and both epinephrine and norepinephrine were 16% higher at night. Among couples who were still married, Time 1 conflict ACTH levels were twice as high among women whose marriages were troubled 10 years later than among women whose marriages were untroubled. Couples whose marriages were troubled at follow-up produced 34% more norepinephrine during conflict, 24% more norepinephrine during the daytime, and 17% more during nighttime hours at Time 1 than the untroubled.

Growth retardation is associated with changes in the stress response system and behavior in school-aged jamaican children

In the developing world, 39% of children <5 y old are short for their age (stunted, defined as height-for-age less than -2 SD of National Center for Health Statistics references), and many have poor levels of mental development along with behavioral problems. We showed previously that 8- to 10-y-old children from a longitudinal cohort who experienced early childhood stunting had altered hypothalamic-pituitary-adrenocortical (HPA) and sympathetic-adrenomedullary (SAM) system activity. We repeated the study with 31 newly recruited, stunted Jamaican school children (less than -2.0 SD height-for-age) and nonstunted controls (n = 31, more than -1.0 SD height-for-age) matched for sex, age and school. All children were tested in a 1.5-h session, including psychological and physiologic stressors, in which their behaviors, salivary cortisol concentrations and heart rates were measured. In addition, we measured urinary catecholamine (epinephrine, norepinephrine, dopamine) concentrations, which were not reported for the children in the longitudinal cohort. After controlling for covariates that differed between groups (child intelligence quotient, body mass index and birth weight), stunted children had faster resting heart rates while lying and sitting (P < 0.05) and also during psychological testing (P < 0.05), as well as higher concentrations of urinary epinephrine (P < 0.05) and norepinephrine (P < 0.05), compared with nonstunted children. In addition, the stunted children were less happy (P < 0.01), more inhibited (P < 0.01) and more frustrated (P < 0.05) during the psychological tests than nonstunted children. These results suggest that growth retardation is associated with alterations in stress-sensitive systems, particularly the SAM system, and that this connection may contribute to the poor levels of development observed in stunted children.

Marriage and health: his and hers

This review focuses on the pathway leading from the marital relationship to physical health. Evidence from 64 articles published in the past decade, particularly marital interaction studies, suggests that marital functioning is consequential for health; negative dimensions of marital functioning have indirect influences on health outcomes through depression and health habits, and direct influences on cardiovascular, endocrine, immune, neurosensory, and other physiological mechanisms. Moreover, individual difference variables such as trait hostility augment the impact of marital processes on biological systems. Emerging themes in the past decade include the importance of differentiating positive and negative dimensions of marital functioning, the explanatory power of behavioral data, and gender differences in the pathways from the marital relationship to physiological functioning. Contemporary models of gender that emphasize self-processes, traits, and roles furnish alternative perspectives on the differential costs and benefits of marriage for men's and women's health.

Psychological factors associated with coronary heart disease

Objectives: Psychological coronary-proncncss is most probably one of the first recognised risk factors for coronary heart disease (CHD). The mechanisms by which psychological risk factors might exert their influence on the cardiovascular system arc less clear than those for the more standard biological risk factors. The aim of this review was to classify all possible mechanisms of potentiation of CHD by psychological factors.

Method: A MEDLINE search was conducted by selecting literature on both standard biological risk factors (eg. dyslipidaemia, hypertension, smoking) and psychological risk factors (eg. personality traits, behavioural characteristics, coping with stress) for CHD.

Results: It was suggested that six biological mechanisms could mediate psychological influences specifically for CHD, of course, together with the seventh mechanism of general alterations in health-related behaviours. These are: increased oxygen demand of the heart muscle, decreased blood supply to the heart muscle, increased concentration of blood, enhanced blood clotting, increase in cholesterol and other plasma lipids, disturbances of blood sugar level, and alterations in health-related behaviours.

Conclusions: If more studies of CHD were conducted with both physical and psychological risk factors simultaneously, it would be possible to investigate which of the above suggested mechanisms are important, which could in turn substantially improve both primary and secondary preventive measures.

Influence of cholesterol and fasting insulin levels on blood pressure reactivity

OBJECTIVE

This study examined how cholesterol and fasting insulin levels are related to blood pressure reactivity to behavioral stressors.

METHODS

Subjects (N = 116) were 20 to 52 years old, at 80% to 150% of ideal weight, and had an average fasting cholesterol level of 183 mg/dl. Stressor tasks included mirror star tracing and a videotaped speech task. Changes from baseline were calculated for systolic and diastolic blood pressure.

RESULTS

Neither cholesterol nor insulin was independently related to blood pressure change scores. However, after controlling for body mass, a two-way analysis of variance revealed a significant cholesterol-by-insulin interaction for change in diastolic blood pressure (p = .022). Subjects in the high-cholesterol/high-insulin group showed the greatest increase in diastolic blood pressure reactivity.

CONCLUSIONS

In a general population, people with a below-average cholesterol level experience only moderate cardiovascular reactivity to mental stressors regardless of their fasting insulin level. However, for people with an above-average cholesterol level, fasting insulin level is an important factor in determining potential reactivity to mental stressors. These findings highlight the importance of adequate sample size to allow for the analysis of such interactions in future studies of cholesterol, insulin, and blood pressure reactivity.

Adrenocortical responses to psychological stress and risk for hypertension

Excessive and prolonged stress-induced cortisol changes may contribute to or be a marker of essential hypertension. Cortisol is a central component of the stress response, and it interacts with sympathetic and renal mechanisms contributing to increased blood pressure (BP). Although research in individuals with already established hypertension failed to show consistent abnormalities in adrenocortical output, cortisol responses to psychological stress are greater and more persistent in persons at high risk for hypertension relative to low-risk normotensives. Considering the heterogeneous and multifactorial polygenic nature of hypertension and the fact that cortisol affects several BP related processes, and regulates expression of genes involved in BP, it is possible that this hormone is involved in at least a sub-type of hypertension. Recent studies evaluating cortisol tissue sensitivity, cortisol production and cortisol metabolic rate in hypertension-prone persons support the possibility that cortisol may serve as an intermediate phenotype of hypertension. In this review, we discuss components of the stress responses, factors influencing the adrenocortical response, adrenocortical activity in hypertension, and we propose pathways that mediate effects of stress-induced cortisol on BP.

Hypothalamic-pituitary-adrenocortical responses to psychological stress and caffeine in men at high and low risk for hypertension

OBJECTIVE

This study examined pituitary-adrenocortical responses to dietary doses of caffeine (3.3 mg/kg, equivalent to 2 to 3 cups of coffee), alone and combined with behavioral stress, in men at high risk versus low risk for hypertension. A randomized, double-blind, caffeine-placebo crossover design was used.

METHOD

Adrenocorticotropic hormone (ACTH) and cortisol levels in plasma were assessed at rest and in response to 60-minutes of continuous work on a mental stressor (arithmetic) and a psychomotor task (reaction time) on four test sessions held on separate days.

RESULTS

Tasks alone caused greater ACTH and cortisol increases in high risk men than in the low risk group. Caffeine alone elevated ACTH and cortisol in both groups, with more immediate responses in the high risk group. Both groups showed significant ACTH and cortisol responses to caffeine plus tasks, with the high risk group showing more persistent elevations. The high risk group also showed the highest levels of ACTH and cortisol after caffeine plus tasks.

CONCLUSIONS

These findings demonstrate for the first time the combined effects of caffeine plus stress on ACTH and demonstrate greater corticosteroid effects in hypertension-prone men. As such, they may have implications for the dietary use of caffeine during periods of stress and in those at risk for hypertension.

Marital stress: immunologic, neuroendocrine, and autonomic correlates

Ninety newlywed couples (mean age = 25), selected on the basis of extremely stringent mental and physical health criteria, were admitted to a hospital research unit for 24 hours to provide a detailed assessment of conflict-resolution behaviors and changes in autonomic, endocrine, and immune function. Among these newlyweds, negative or hostile behaviors during marital conflict (coded from videotaped interactions) were associated with increased levels of epinephrine, norepinephrine, growth hormone, and ACTH as well as greater immunological change over the subsequent 24 hours. Wives demonstrated greater and more persistent physiological changes related to marital conflict than husbands. To assess the generalizability of these physiological changes, a similar laboratory paradigm was used with 31 older couples (mean age = 67) who had been married an average of 42 years. Consistent with the data from newlyweds, both endocrinological and immunological data showed significant relationships to negative behavior during marital conflict in these older couples. These findings suggest that abrasive marital interactions have important endocrinological and immunological correlates.

Stress and personality as factors in women's cardiovascular reactivity

An experiment was conducted to investigate the relationships among Type A behavior, hostility and cardiovascular reactivity (CVR) in women. Changes in heart rate, blood pressure and skin conductance from baseline to task levels were used to assess reactivity. These measures were obtained from 96 women during a seated baseline period, a reaction time task and during an oral IQ quiz. Analyses indicated that Type A and high hostile women were more reactive to an oral IQ quiz and reaction time stressors than Type B and low hostile women. Specifically, Type As showed significantly greater increases in systolic blood pressure in the reaction time task and greater mean arterial pressure and systolic blood pressure increases in the IQ quiz. High hostiles evidenced significantly higher systolic blood pressure and diastolic blood pressure in the RT task and higher mean arterial pressure and diastolic blood pressure in the IQ quiz. It was concluded that Type A personality and hostility can predict greater reactivity in women to two different stressors. The oral quiz generated greater reactivity than the RT task and thus may be a more stressful task.

Psychological stress does not affect plasma catecholamines in subjects with cardiovascular disorder

Whereas the effects of cardiac transplantation on the catecholamine response to physical exercise have been studied previously, the impact on psychological stress is unknown. Here, the arterial catecholamine response to the Stroop test of patients with an orthotopic heart transplant (OHT) was compared with that in subjects who had received a coronary artery bypass graft (CABG) or who were in heart failure and destined for a heart transplant (HF). Subjects were tested whilst sitting and their usual drug therapy was maintained. The Stroop test increased subjects' subjective tension but did not affect arterial concentrations of adrenaline or noradrenaline in any group of subjects. Also, the concentration of both catecholamines was significantly higher in OHT and CABG subjects than in the HF group, but their relative concentration was unaffected by cardiovascular status or stress. It is concluded that the absolute concentrations of arterial catecholamines, but not their relative concentrations, depend on clinical status. Moreover, under these test conditions, subjects with a history of cardiovascular disorder do not show the normal catecholamine response to psychological stress.

Empirical contributions

To evaluate the possible negative association between risk for hypertension and pain sensitivity by in women 24 healthy young adult women with a parental history of hypertension and 24 without a parental history of hypertension participated in 2 laboratory sessions in which electric shock and the cold-pressor test were administered To assess the possible role of stress-induced analgesia in blood pressure-related hypoalgesia, the sessions were identical with the exception of the fact that participants were exposed to a stressful 20-min videogame before the pain stimuli on one occasion and a nonstressful control task on the other. Women with a parental history of hypertension and high blood pressure reactivity to the videogame displayed a reduced sensitivity to electric shock on both days, suggesting that risk for hypertension is associated with reduced sensitivity to at least some pain stimuli in women. Blood pressure reactivity to stress-associated baroreceptor stimulation was not implicated as a mediator of decreased pain perception. However, other analyses revealed an effect of family history on shock pain only among women who report relatively high anxiety, suggesting that other aspects of the stress response may be involved in this phenomenon.

Sources of human urinary epinephrine

The kidney is a likely source for some urinary epinephrine (E) since adrenalectomized animals and humans continue to excrete urinary E and the human kidney contains E synthesizing enzymes. We studied subjects during an intravenous infusion of 3H-E to determine the fraction of urinary E derived from the kidney. Eight normal subjects (CON) and 5 older, heavier hypertensives (OHH) ate a light breakfast along with ascorbic acid supplementation and had intravenous and arterial lines placed. They received an infusion of 3H-E and had an oral water load. During the final hour of 3H-E infusion, urine and arterial blood samples were collected for 3H-E and E levels. After the 3H-E infusion was abruptly discontinued, arterial blood samples were collected to measure 3H-E kinetics. The total body clearance of 3H-E was about 2,500 ml/min from plasma and clearance of 3H-E to urine was about 170 ml/min. CON had plasma E levels of 43 +/- 4 pg/ml. Their predicted rate of clearance of E from plasma to urine of 7,471 +/- 865 pg/min was less than (P = 0.018) the actual urinary E excretion of 15,037 +/- 2,625 pg/min. Thus, 43 +/- 9% of urinary E in CON was apparently derived from renal sources and not filtered from blood. Among OHH 85 +/- 4% of urinary E was derived from the kidney, significantly (P < 0.01) different from CON. The OHH also produced much more urinary E than predicted from plasma 3H-E clearance into urine (P = 0.03). A major fraction of urinary E is not filtered from the blood stream but is apparently derived from kidney. A small fraction of urinary E may be derived from E stored in nerve endings along with norepinephrine, but this probably represents less than 2% of urinary E. Renal cleavage of E sulfate into E may be another potential source of urinary E. Some, and perhaps most, urinary E not filtered from the bloodstream is derived from renal N-methylation of norepinephrine as the human kidney has two enzymes capable of converting norepinephrine to E. In conclusion, a major portion of urinary E is derived from the kidney and not filtered from the bloodstream. This is an important factor in the interpretation of urine E levels. Renal E could alter renal blood flow, electrolyte reabsorption, and renin release prior to excretion into urine.

Reproducibility of blood pressure and heart rate reactivity: a meta-analysis

Reproducibilities of blood pressure and heart rate (HR) reactivity reported in studies assessing responses to the same laboratory stressors across occasions were reviewed with meta-analytic techniques. Changes in HR had the greatest reproducibility (r = .555), followed by systolic blood pressure (SBP) (.407) and diastolic blood pressure (DBP) (.348). Both SBP and HR response reproducibility was higher at shorter test-retest intervals, whereas DBP values varied unsystematically with length of test-retest interval. Older samples exhibited higher SBP and DBP reproducibility to stressors. SBP and DBP reproducibilities were better for tasks that did not make speech demands. The reliability of reactivity assessment was higher when based on three or more measurements. On the basis of available evidence, the drop in stress reproducibility, as test-retest interval increases, places limits on the viability of BP reactivity as a strong marker or risk factor for coronary heart disease.