Comparison of urinary and plasma catecholamine responses to mental stress

Relation of Plasma Catecholamine Concentrations and Myocardial Mitochondrial Respiratory Activity in Anesthetized and Mechanically Ventilated, Cardiovascular Healthy Swine

Chronic heart failure is associated with reduced myocardial β-adrenergic receptor expression and mitochondrial function. Since these data coincide with increased plasma catecholamine levels, we investigated the relation between myocardial β-receptor expression and mitochondrial respiratory activity under conditions of physiological catecholamine concentrations. This post hoc analysis used material of a prospective randomized, controlled study on 12 sexually mature (age 20-24 weeks) Early Life Stress or control pigs (weaning at day 21 and 28-35 after birth, respectively) of either sex. Measurements in anesthetized, mechanically ventilated, and instrumented animals comprised serum catecholamine (liquid-chromatography/tandem-mass-spectrometry) and 8-isoprostane levels, whole blood superoxide anion concentrations (electron spin resonance), oxidative DNA strand breaks (tail moment in the "comet assay"), post mortem cardiac tissue mitochondrial respiration, and immunohistochemistry (β2-adrenoreceptor, mitochondrial respiration complex, and nitrotyrosine expression). Catecholamine concentrations were inversely related to myocardial mitochondrial respiratory activity and β2-adrenoceptor expression, whereas there was no relation to mitochondrial respiratory complex expression. Except for a significant, direct, non-linear relation between DNA damage and noradrenaline levels, catecholamine concentrations were unrelated to markers of oxidative stress. The present study suggests that physiological variations of the plasma catecholamine concentrations, e.g., due to physical and/or psychological stress, may affect cardiac β2-adrenoceptor expression and mitochondrial respiration.

Depression interacts with allostatic load to predict cognitive decline in middle age

BACKGROUND

Allostatic load (AL) indicates the cumulative impact of stress on homeostatic mechanisms. Depression and AL have been associated with cognitive deficits, but it is unclear if they do so independently.

METHODS

Using data from middle-aged participants in the observational longitudinal Midlife in the United States (MIDUS) study (n = 704, 57.5 % female, 63.8 ± 10.6 years old in 2014), we assessed whether the effect of prior depression (Composite International Diagnostic Interview Short-Form in 1995) on cognitive decline between 2004 and 2013 (composite Z-scores derived from the Brief Test of Adult Cognition by Telephone and the Stop & Go Switch Task) was moderated by AL Z-scores in 2004 (calculated from biomarkers in blood, urine, and electrocardiography).

RESULTS

A significant depression × AL interaction predicted a decline in a composite cognitive score (β = -0.066, SE=0.029, p = 0.024) and executive function (β = -0.068, SE=0.025, p = 0.007). Depression predicted a decline in composite cognition among those with AL Z-scores above - 0.055. AL subdomains of inflammation and lipid metabolism showed evidence of moderation.

CONCLUSION

Middle-aged adults with depression who had higher allostatic load were at greater risk of cognitive decline. Future studies should evaluate whether the interaction predicts incident dementia, and whether interventions targeting depression or elevated AL in people who have both can attenuate cognitive decline.

Workplace Culture and Biomarkers of Health Risk

Workplace culture has been studied for impact on health risk; however, connections with robust biologic markers of health remain to be established. We examined associations between the work environment and urinary levels of catecholamines and their metabolites as biomarkers of sympathetic nervous system activity, indicative of stress. We recruited participants (n = 219; 2018-2019) from a cardiovascular risk cohort to investigate workplace culture, well-being, and stress. Participants completed seven questionnaires. Urine samples were used to measure catecholamines and their metabolites by LC/MS/MS. Pearson correlation and linear regression models were used after adjusting for demographics and creatinine. Participants reporting higher well-being had lower urinary levels of dopamine, serotonin, and 3-methoxytyramine. Participants reporting a more engaged and more positive workplace had lower levels of dopamine and 3-methoxytyramine. Reported workplace isolation was correlated with higher levels of dopamine and 3-methoxytyramine. Given correlations between catecholamines, we used 3-methoxytyramine for linear regression. In fully adjusted models, in environments with a more positive culture, levels of 3-methoxytyramine remained lower (β = -0.065 ± 0.025, p = 0.01) and indicated a positive association between workplace isolation and 3-methoxytyramine (β = 0.064 ± 0.030, p = 0.04). These findings are consistent with an important relationship between workplace environment and sympathetic nervous system activity.

Differential Responses of Urinary Epinephrine and Norepinephrine to 24-h Shift-Work Stressor in Physicians

Multiple stressors, including 24-h-shifts characterise the working environment of physicians, influencing well-being, health and performance. We aimed to evaluate the effect of the stressor 24-h-shift on the adrenal medullary and sympathoneural system in physicians with the hypothesis that shift work might have different impacts on both systems. Twenty-two physicians collected two 12-h-urine samples ("daytime" and "nighttime") during a 24-h shift ("on-duty") and on a free weekend ("off-duty"), respectively. Urinary excretion rates per m² body surface area were assessed for the catecholamines epinephrine, norepinephrine and their respective free O-methylated metabolites metanephrine and normetanephrine by LC-MS/MS-analysis. The stressor provoked differential responses of epinephrine and norepinephrine. Epinephrine excretion rates showed significant increases from off to on duty. The largest proportional change (off-duty to on-duty) for epinephrine was observed for nighttime (205%), the increase for daytime was 84%. An increase in norepinephrine from off to on duty was only visible for nighttime collections. For the catecholamine metabolites, normetanephrine paralleled norepinephrine and exhibited an increase in excretion from off to on duty during nighttime collections of 53% whereas there was no change during daytime collections (3%). In conclusion: Whilst the 24-h-shift-work stressor in physicians activates the sympatho-adrenomedullary system, represented by epinephrine, the sympathoneural response through norepinephrine reflects mainly an ambulatory position during working hours.

Instant Stress: Detection of Perceived Mental Stress Through Smartphone Photoplethysmography and Thermal Imaging

BACKGROUND

A smartphone is a promising tool for daily cardiovascular measurement and mental stress monitoring. A smartphone camera-based photoplethysmography (PPG) and a low-cost thermal camera can be used to create cheap, convenient, and mobile monitoring systems. However, to ensure reliable monitoring results, a person must remain still for several minutes while a measurement is being taken. This is cumbersome and makes its use in real-life situations impractical.

OBJECTIVE

We proposed a system that combines PPG and thermography with the aim of improving cardiovascular signal quality and detecting stress responses quickly.

METHODS

Using a smartphone camera with a low-cost thermal camera added on, we built a novel system that continuously and reliably measures 2 different types of cardiovascular events: (1) blood volume pulse and (2) vasoconstriction/dilation-induced temperature changes of the nose tip. 17 participants, involved in stress-inducing mental workload tasks, measured their physiological responses to stressors over a short time period (20 seconds) immediately after each task. Participants reported their perceived stress levels on a 10-cm visual analog scale. For the instant stress inference task, we built novel low-level feature sets representing cardiovascular variability. We then used the automatic feature learning capability of artificial neural networks to improve the mapping between the extracted features and the self-reported ratings. We compared our proposed method with existing hand-engineered features-based machine learning methods.

RESULTS

First, we found that the measured PPG signals presented high quality cardiac cyclic information (mean pSQI: 0.755; SD 0.068). We also found that the measured thermal changes of the nose tip presented high-quality breathing cyclic information and filtering helped extract vasoconstriction/dilation-induced patterns with fewer respiratory effects (mean pSQI: from 0.714 to 0.157). Second, we found low correlations between the self-reported stress scores and the existing metrics of the cardiovascular signals (ie, heart rate variability and thermal directionality) from short measurements, suggesting they were not very dependent upon one another. Third, we tested the performance of the instant perceived stress inference method. The proposed method achieved significantly higher accuracies than existing precrafted features-based methods. In addition, the 17-fold leave-one-subject-out cross-validation results showed that combining both modalities produced higher accuracy than using PPG or thermal imaging only (PPG+Thermal: 78.33%; PPG: 68.53%; Thermal: 58.82%). The multimodal results are comparable to the state-of-the-art stress recognition methods that require long-term measurements. Finally, we explored effects of different data labeling strategies on the sensitivity of our inference methods. Our results showed the need for separation of and normalization between individual data.

CONCLUSIONS

The results demonstrate the feasibility of using smartphone-based imaging for instant stress detection. Given that this approach does not need long-term measurements requiring attention and reduced mobility, we believe it is more suitable for mobile mental health care solutions in the wild.

Association Between Residential Greenness and Cardiovascular Disease Risk

Background Exposure to green vegetation has been linked to positive health, but the pathophysiological processes affected by exposure to vegetation remain unclear. To study the relationship between greenness and cardiovascular disease, we examined the association between residential greenness and biomarkers of cardiovascular injury and disease risk in susceptible individuals. Methods and Results In this cross-sectional study of 408 individuals recruited from a preventive cardiology clinic, we measured biomarkers of cardiovascular injury and risk in participant blood and urine. We estimated greenness from satellite-derived normalized difference vegetation index ( NDVI ) in zones with radii of 250 m and 1 km surrounding the participants' residences. We used generalized estimating equations to examine associations between greenness and cardiovascular disease biomarkers. We adjusted for residential clustering, demographic, clinical, and environmental variables. In fully adjusted models, contemporaneous NDVI within 250 m of participant residence was inversely associated with urinary levels of epinephrine (-6.9%; 95% confidence interval, -11.5, -2.0/0.1 NDVI ) and F2-isoprostane (-9.0%; 95% confidence interval, -15.1, -2.5/0.1 NDVI ). We found stronger associations between NDVI and urinary epinephrine in women, those not on β-blockers, and those who had not previously experienced a myocardial infarction. Of the 15 subtypes of circulating angiogenic cells examined, 11 were inversely associated (8.0-15.6% decrease/0.1 NDVI ), whereas 2 were positively associated (37.6-45.8% increase/0.1 NDVI ) with contemporaneous NDVI . Conclusions Independent of age, sex, race, smoking status, neighborhood deprivation, statin use, and roadway exposure, residential greenness is associated with lower levels of sympathetic activation, reduced oxidative stress, and higher angiogenic capacity.

Cardiac reactivity and preserved performance under stress: two sides of the same coin?

In the present experiment, cognitive control under stress was investigated using a real-life paradigm, namely an evaluation flight for military student pilots. The magnitude of cognitive interference on color-word, numerical and emotional Stroop paradigms was studied during a baseline recording and right before the test flight. Cardio-respiratory parameters were simultaneously assessed during rest and the performance of the Stroop tasks. Cognitive data suggested a different speed/accuracy trade-off under stress, and no modulation of the interference effect for color words or numerical stimuli. However, we observed a major increase in error rates for specific emotional stimuli related to the evaluation situation in the stress condition. The increase in cognitive interference from emotional stimuli, expressed as an increase in error rates, was correlated to the decreased cardiac reactivity to challenge in the stress situation. This relationship is discussed in the framework of Sanders' (1983) model of stress and performance. In terms of future research, this link warrants a fruitful lead to be followed for investigating the causal mechanism of performance decrements under the influence of stress.

Comparing real-life and laboratory-induced stress reactivity on cardio-respiratory parameters: differentiation of a tonic and a phasic component

To recreate stress in laboratory conditions, the nature of the elicited physiological reactions to the presentation of mental tasks has been extensively studied. However, whether this experimental response is equivalent to real-life stress reactivity is still under debate. We investigated cardio-respiratory reactivity to a sequential protocol of different mental tasks of varying difficulties, some of them involving emotional material, and repeated the measures in a baseline and in a real-life stress situation. R-R interval (RRI), breathing frequency and volumes, and respiratory sinus arrhythmia (RSA) were computed. Baseline results showed a superior sensitivity of respiratory parameters to mental task load over RRI and RSA, no effect of task difficulty or emotional material, and a habituation response of all parameters along the protocol. Stress results showed a dual effect: first, a decreased RRI and RSA in rest values, and second, a decreased reactivity in RRI in response to mental tasks. These findings are discussed through the interaction of activation, considered to be a tonic variable, and arousal, as a phasic response.

Muscle blood flow response to mental stress and adrenaline infusion in man: microdialysis ethanol technique compared to (133)Xe clearance and venous occlusion plethysmography

BACKGROUND AND AIM

Adrenaline, administered locally by microdialysis in skeletal muscle, causes vasoconstriction around the microdialysis catheter. This is contrary to the vasodilation that normally occurs when adrenaline is infused intravenously or intra-arterially. The hypothesis was tested that vasoconstriction, measured by microdialysis, would not occur with two interventions causing increased plasma levels of adrenaline, mental stress and intravenous adrenaline infusion (0.1 nmol kg(-1) min(-1)).

METHODS

Twenty-four men (27 +/- 1.6 years) underwent these interventions. Blood flow was determined by the microdialysis ethanol technique and (133)Xe clearance (gastrocnemius muscle, medial head) and by venous occlusion plethysmography (calf).

RESULTS

The ethanol outflow/inflow ratio, which is inversely related to blood flow, decreased to 92.0 +/- 3.4% of basal, P = 0.014 (mean +/- SEM, n = 16) during the mental stress test, but increased to 108.3 +/- 2.2% of basal, P = 0.001 (n = 16) during the adrenaline infusion. The latter increase was abolished when adrenaline was infused during alpha-receptor blockade by phentolamine. On the contrary, by (133)Xe clearance and venous occlusion plethysmography, blood flow increased during both interventions; 2.0-1.7-fold (mental stress) and 1.3-1.4-fold (adrenaline infusion), respectively, P<0.05.

CONCLUSION

Adrenaline causes vasoconstriction in skeletal muscle when blood flow is measured with the microdialysis ethanol technique, irrespective of the mode of administration. The discrepant blood flow result obtained with the microdialysis ethanol technique might, at least partly, be explained by differential diffusion properties of ethanol and (133)Xe. An additional or alternative explanation might be that an inserted microdialysis catheter shifts the balance of vasoconstrictor and vasodilator effects of adrenaline in skeletal muscle.

Maternal catecholamine levels in midpregnancy and risk of preterm delivery

Associations between stress hormones and preterm delivery have not been fully explored. In this study, pregnant women enrolled from 52 clinics in 5 Michigan communities (1998-2004) provided urine samples for 3 days (waking and bedtime) during midpregnancy. Urinary catecholamine levels (epinephrine, norepinephrine, and dopamine) were measured in a subcohort (247 preterm and 760 term deliveries), and a 3-day median value was calculated. Polytomous logistic regression models assessed relations between catecholamine quartiles (of the median) and a 4-level outcome variable (i.e., term (referent) and 3 preterm delivery subtypes: spontaneous; premature rupture of membranes; and medically indicated). Final models incorporated other relevant covariates (e.g., creatinine, demographic, behavior). The risk of spontaneous preterm delivery was increased in the highest versus lowest quartile of norepinephrine and dopamine: norepinephrine, waking (adjusted odds ratio (AOR) = 3.7, 95% confidence interval (CI): 1.8, 7.9) and bedtime (AOR = 2.5, 95% CI: 1.3, 4.9); dopamine, waking (AOR = 2.6, 95% CI: 1.4, 5.1) and bedtime (AOR = 2.3, 95% CI: 1.2, 4.6). Adjusted odds ratios were further strengthened after removing women whose placentas showed evidence of acute infection or vascular pathology. High catecholamine levels in maternal urine may be indicative of excess stressors and/or predisposition to elevated sympathetic activation that contributes to increased risk of spontaneous preterm delivery.

Plasma catecholamines, blood pressure responses and perceived stress during mental arithmetic stress in young men

We assessed plasma noradrenaline (NA) and adrenaline (A) at rest during a hyperinsulinaemic glucose clamp and responses to a mental arithmetic stress test (MST) in relation to blood pressure (BP) responses (Finapres) and distress in 20 men with high (> or =140/90 mmHg) and 21 men with normal (< or =115/75 mmHg) screening BP, 21-24 years of age. Perceived stress, effort and overall discomfort were scored 1-10. Catecholamines and BP increased in both groups, change in diastolic BP (DeltaDBP; 9.9 vs. 3.8 mmHg, p < 0.05) and DeltaDBP carryover (recovery period minus baseline) (7.2 vs. 2.2 mmHg, p < 0.01) being greater in men with high screening BP. Independently of BP status, change in systolic BP (DeltaSBP) and DeltaSBP carryover were related to A (both p < 0.001), and DeltaDBP and DeltaDBP carryover to DeltaNA (both p < 0.001). The subjective score sum correlated with maximal NA (rs = 0.40) and A (rs = 0.37) (both p < 0.05). Maximal NA was independently related to stress (p < 0.05) and the subjective score sum (p < 0.01). DeltaA% was greater in the high- (score > or =6) than in the low-stress category, independently of BP status (p < 0.05). High screening BP is associated with impaired BP recovery after mental stress. Plasma catecholamine responses are related to BP responses and carryover effects, and reflect perceived stress in young men.

Stress during simulated emergency transportation in a rescue helicopter: cross-correlation between stress hormones, vital functions and subjective well-being

Vital functions and stress hormone levels during simulated emergency helicopter transport in healthy volunteers. Twenty-three volunteers were subjected to a simulated 15 minute rescue helicopter transport. We determined vital functions, ACTH, cortisol and prolactin during the flight and filled in a standardized questionnaire before and after the flight. Data were analysed descriptively, by means of cross tabulation, Spearman rank correlation and cross-correlation technique. During take-off we recorded a significant increase of vital parameters such as heart rate. Prolactin concentration rose slightly after the start. Maximum cortisol and ACTH levels were found before take-off and then they decreased gradually. As expected, ACTH and cortisol cross-correlated significantly without any relevant time lag. Test items showed a feeling of fear and concern before take off. After the flight the volunteers reported having less stress than expected. Particularly, diastolic blood pressure and prolactin levels were markedly associated with questionnaire items such as behaviour of the staff or nausea. Heart rate significantly correlated with anxiety scores. Helicopter transportation induced a marked stress reaction in healthy volunteers, which speaks in favour of smooth transports in modern helicopters and adequate behaviour towards the patient of the staff.

Road transportation affects blood hormone levels and lymphocyte glucocorticoid and β-adrenergic receptor concentrations in calves

The effect of transportation on blood cortisol and catecholamine levels, lymphocyte glucocorticoid receptor (GR) and beta-adrenergic receptor (beta-AR) concentrations was investigated in calves. Blood samples were collected from 24 six-month-old calves before departure (T(0)), on arrival (T(1)), and at 24 h (T(2)) and one week (T(3)) after arrival. Animals were loaded and transported about 950 km, from the Midy-Pyrenes region (Cahors, France) to the Piedmont region (Italy), over a total of 14 h. Serum cortisol levels and plasma catecholamines (adrenaline, noradrenaline) were determined by radioimmunoassay. Lymphocyte GRs and beta-ARs were measured through binding assays. A significant (P < 0.05) increase in cortisol and catecholamine concentrations was observed immediately after transport. The increase in hormone levels at time T(1) was negatively correlated with lymphocyte GR and beta-AR concentrations. At times T(2) and T(3), blood cortisol and catecholamine levels and lymphocyte GRs and beta-ARs returned to normal. The results demonstrate the activation of the hypothalamic-pituitary-adrenal axis and the catecholaminergic system in long-term transported calves. However, these systems returned to normal within 24 h after the end of transport.

The effect of midazolam on stress levels during simulated emergency medical service transport: a placebo-controlled, dose-response study

Patients in the emergency medical service (EMS) may have increased endogenous catecholamines because of pain or fear and may benefit from sedation similar to premedication in the hospital. During a simulated EMS scene call, 72 healthy male volunteers were either transported by paramedics from a third-floor apartment through a staircase with subsequent EMS transport with sirens (three stress groups of n = 12; total, n = 36) or asked to sit on a chair for 5 min and lie down on a stretcher for 15 min (three control groups of n = 12; total, n = 36). Catecholamine plasma samples were measured in the respective stress and control groups at baseline and after placebo IV (n = 12) or 25 (n = 12) or 50 (n = 12) microg/kg of midazolam IV throughout the experiment, respectively. Statistical analysis was performed with analysis of variance; P < 0.05 was considered significant. The Placebo Stress versus Control group, but not the 50 microg/kg Stress Midazolam group, had both significantly increased epinephrine (73 +/- 5 pg/mL versus 45 +/- 5 pg/mL; P < 0.001) and norepinephrine (398 +/- 34 pg/mL versus 278 +/- 23 pg/mL; P < 0.01) plasma levels after staircase transport. After EMS transport, the Placebo Stress versus Control group had significantly increased epinephrine (51 +/- 4 pg/mL versus 37 +/- 4 pg/mL; P < 0.05) but not norepinephrine (216 +/- 24 pg/mL versus 237 +/- 18 pg/mL) plasma levels, whereas no significant differences in catecholamine plasma levels occurred between groups after either 25 or 50 microg/kg of midazolam. In conclusion, simulated EMS patients may be subject to more stress during staircase transport than during transport in an EMS vehicle. Titrating sedation with 25 microg/kg of midazolam significantly reduced endogenous catecholamines but not heart rate.

IMPLICATIONS

Simulated emergency medical service patients were more likely to be stressed when being transported by paramedics through a staircase than in an ambulance. Accordingly, it may be beneficial to inject sedative drugs before initiating transport to ensure patient comfort and safety.

Emergency medical service transport-induced stress? An experimental approach with healthy volunteers

This randomized controlled trial was designed to evaluate the effects of simulated emergency medical service (EMS) transport related stress on hemodynamic variables, and catecholamine plasma levels. A total of 32 healthy male volunteers were randomized to being carried by paramedics from a third-floor apartment through a staircase with subsequent high-speed EMS transport with lights and sirens (stress; n = 16); or sitting on a chair for 5 min, and lying on a stretcher for 15 min (control; n = 16). Blood samples and hemodynamic variables were taken in the apartment before transfer, at the ground floor, and at the end of EMS transport in the stress group, and at corresponding time points in the control group. The stress versus control group had both significantly (P < 0.05) higher mean +/- SEM epinephrine (71 +/- 7 versus 37 +/- 3 pg/ml), and norepinephrine (397 +/- 29 versus 299 +/- 28 pg/ml) plasma levels after transport through the staircase. After EMS transport, the stress versus control group had significantly higher epinephrine (48 +/-6 versus 32 +/- 2 pg/ml), but not norepinephrine (214 +/- 20 versus 264 +/- 31 pg/ml) plasma levels. Heart rate increased significantly from 72 +/- 2 to 84 +/- 3 bpm after staircase transport, but not during and after EMS transport. In conclusion, volunteers being carried by paramedics through a staircase had a significant discharge of both epinephrine and norepinephrine resulting in increased heart rate, but only elevated epinephrine plasma levels during EMS transport. Transport through a staircase may reflect more stress than emergency EMS transport.

The influence of restraint immobilization stress on the concentration qf bioamines and cortisol in plasma of Pietrain and Duroc pigs

Forty-five Duroc (recognized as not susceptible to stress) and 34 Pietrain (susceptible to stress) pigs were subjected to immobilization stress in a prone position for 5, 15, 30 and 60 min. Plasma concentrations of epinephrine (E), norepinephrine (NE), dopamine (DA) and cortisol (C) were determined in response to restraint stress. The concentrations of E, NE and DA were different between the two strains of pigs (some significant interactions); the highest response was seen after 5 min of stress. The concentration of plasma C increased with duration of stress and there was a significant interaction between strain of animals and the time of stress. Our data substantiate the use of E, NE, DA and C as indicators of stress in swine as early as 5 min after exposure to the stressor. It is also shown that stress-susceptible Pietrain pigs had higher plasma concentrations of E, NE and DA than Duroc pigs.

Behaviorally-evoked plasma catecholamine response and 24-hour excretion of urinary catecholamines among cardiac and vascular reactors

Individuals differ in the cardiac and vascular processes that underlie blood pressure elevations evoked by environmental stimuli; such differences may reflect variability in sympathoadrenal response. We separated 108 healthy, young-adult males into those with predominant elevations in either cardiac output or peripheral resistance when exposed to psychological challenges. We then asked if they differed on other measures of cardiovascular response, concomitant plasma catecholamine reactions or 24-h urinary excretion of catecholamines. Cardiac reactors, relative to vascular reactors, showed reduced cardiac pre-ejection period, a smaller reduction in stroke volume, and elevated plasma epinephrine response and 24-h urinary epinephrine excretion. Vascular reactors, relative to cardiac reactors, responded to mental stress with more elevated diastolic blood pressure, a rise in peripheral resistance and pulse wave velocity, and a greater reduction in stroke volume. Vascular reactors, however, did not show plasma norepinephrine response or 24-h urinary norepinephrine excretion that was greater than cardiac reactors. The results provide partial support for the hypothesis that variability in sympathoadrenal activity contributes to individual differences in cardiac and vascular reactivity, and extend prior observations by demonstrating covariation of behaviorally-elicited cardiac reactivity with the 24-h excretion of epinephrine.

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.

The Biological Stress Response and Lifestyle: Catecholamines and Blood Pressure

Many measures in human biology that are studied as immutable traits are actually fluctuating physiological functions that adjust body systems to rapid changes in the environment. This overview discusses what has been learned about the response to the stressors inherent in continuously changing microenvironments in modern Western societies of two related physiological functions: the release of catecholamines and blood pressure. The review shows that many factors that are part of or influence lifestyle—including perception and cognitive state, the nature of the social situation, foods, stimulants and exercise—and external conditions such as temperature, continuously alter catecholamine levels and blood pressure. Because lifestyle stress may be an important selective force in human populations, studies of dynamic functions that react to it, such as catecholamine release and blood pressure, may be important in understanding the ongoing dynamics of human evolution.

Isolation of specific interference processing in the Stroop task: PET activation studies

The Stroop task, in which subjects must name the color of letters that spell color words different than the color-to-be-named, provides an important experimental paradigm for the study of selective attention. Cerebral blood flow activation studies have not always demonstrated consistent activation patterns; inconsistent results may reflect nonspecific responses, such as arousal or anticipation, rather than cerebral networks specific to Stroop interference processing. In order to identify regions consistently implicated in Stroop interference processing, we undertook two experiments with a Stroop interference paradigm and contrasting lexical and nonlexical control conditions. In our first experiment, standard Stroop stimuli, e.g., the word "RED" displayed in a green font, were contrasted with color naming of the font of noncolor words and color naming of a false font. In our second experiment, we compared Stroop stimuli with colored symbols and a control condition designed to elicit nonspecific interference-taboo words displayed in color fonts. Only two brain regions showed a consistent CBF change in both experiments. Activation in the left inferior frontal gyrus reflected processing more specific to the Stroop task, while deactivation in the right superior temporal gyrus occurred for the Stroop and the taboo conditions, consistent with more nonspecific processing. Activation in the anterior cingulate cortex occurred in only one comparison in one experiment and may not reflect functions central to overcoming Stroop interference.

Decreased sympatho-adrenal activity in diabetic patients with autonomic dysfunction following mental stress

The sympathetic nervous system is of major importance in the regulation of numerous physiological functions. While it is clearly established that there is a decreased noradrenergic status in people with autonomic neuropathy, the epinephrine secretion is much more controversial. Basal and mental stress-stimulated plasma catecholamine levels were measured in 42 diabetic patients with and without pathological cardiovascular function tests and in 13 healthy, non-diabetic control subjects. In addition, the excretion of catecholamines was measured in a 24 h urine collection and compared with the stress stimulated plasma levels. During mental stress exposure a diminished epinephrine secretion was found in diabetic patients with autonomic neuropathy compared with diabetic patients without neuropathy and the healthy control group (p < 0.05: respectively). The decreased epinephrine response to mental stress was strongly correlated with a diminished urinary excretion of this "neurotransmitter' (r = 0.46; p < 0.01). Diabetic patients suffering from cardiovascular autonomic neuropathy exhibit a diminished sympatho-adrenal response following mental stress exposure. Both measurement of urinary and mental stress stimulated plasma epinephrine levels following mental stress provide reliable information regarding sympatho-adrenal activity in diabetic patients.

Reproducibility of the cardiovascular reactivity to a computerized version of the Stroop stress test in normotensive and hypertensive subjects

The 1-month reproducibility of haemodynamic and sympathoadrenal responses to a standardized mental stress test was studied in ten normotensive and ten hypertensive individuals. The stress test was a computerized adaptation of the Stroop test and sympathetic activity was evaluated by measuring urinary catecholamine excretion. Three-way analysis of variance (stress, session, blood pressure) revealed significant increases in systolic and diastolic blood pressures and in heart rate during the stress test. Test-retest correlation coefficients for basal stress levels, and stress-induced variations were significant (r from 0.59 to 0.88). The stress test induced a significant increase in urinary noradrenaline excretion with large intra- and interindividual variability. The significant test-retest correlations and the lack of period effect for haemodynamic parameters indicated good temporal stability. However, a slight decrease in stress-induced reactivity was observed. This standardized mental stress test may be useful in epidemiological and therapeutic trials to measure blood pressure and heart rate responses, but measurement of urinary catecholamine excretion does not provide any additional information.

Relationship between erythrocyte magnesium, plasma electrolytes and cortisol, and intensity of symptoms in major depressed patients

53 male and female drug-free major depressed patients were separated into three groups according to the severity of the depression. In the entire regrouped population, plasma and erythrocyte magnesium (Mg) were shown to increase as compared with 48 healthy controls, confirming our previous studies. The middle and highly depressed patients had higher erythrocyte and also plasma Mg levels than either lowly depressed patients or controls. Only, a few differences were noticed in plasma sodium, potassium and calcium (Ca) in the three groups of patients, except for ultrafiltrable plasma Ca, measured for the first time in affective disorders. Thus, erythrocyte and also plasma Mg are shown to be associated with the intensity of the depression. As blood hypomagnaesemia is often related to hyperexcitability, further investigations are actually in process to shown whether hypermagnesaemia might be, in contrast, associated with psychomotor retardation as observed in many depressed patients.

The effect of transport stress on plasma levels of catecholamines, cortisol, corticosteroid-binding globulin, blood cell count, and lymphocyte proliferation in pigs

The effect of transport stress on the plasma levels of catecholamines, cortisol, and corticosteroid-binding globulin were studied in 6 gilts. To assess the effect on immune status, white blood cells were also counted and the cell-mediated immunity was estimated. The adrenaline level increased significantly during transport, from a basal mean level of 0.03 ng/ml to a plateau level of 0.11 to 0.12 ng/ml. The noradrenaline level fluctuated, but not constantly, during transport. The mean plasma cortisol level before loading was approximately 40 nmol/l and rose immediately after the start of transport to 70 nmol/l (p < 0.05) and to 87 nmol/l (p < 0.01) within 10 and 30 min, respectively. After unloading the cortisol level rapidly decreased and a minimum level was seen 4 h after the transport, whereafter the diurnal rhythm was resumed. The plasma corticosteroid-binding globulin level increased nonsignificantly during the day of transport, from 25 nmol/l to a level of 34 nmol/l, and it continued to increase until a plateau level was reached on the second day after transportation. The total white blood cell number increased significantly (from 13.7 to 15.5 x 10(9) cells/l), the number of lymphocytes decreased significantly (from 8.4 to 7.0 x 10(9) cells/l), and the number of polymorphonuclear neutrophils increased significantly (from 4.3 to 7.2 x 10(9) cells/l) during transport. No significant variation in the proliferation response was seen in the whole blood cell cultures. The main results were the significant signs of simultaneous activity of both the adrenal cortex and the adrenal medulla during transport.

Plasma catecholamines--analytical challenges and physiological limitations

Catecholamines in plasma may be measured to assess sympathoadrenal activity. Numerous assay methodologies have been published, illustrating the fact that there are many analytical problems. Different methodologies are discussed briefly. A plea for better validation, especially with regard to specificity (which should not be confused with sensitivity or reproducibility), is made. Plasma NA is a frequently used marker for sympathetic nerve activity in humans, but the data obtained are often misinterpreted due to lack of appreciation of the physiological determinants of the NA concentration measured. NA overflow from an organ gives a good reflection of nerve activity in that organ. However, sympathetic nerve activity is highly differentiated, particularly during stress, and conventional plasma NA levels (usually forearm venous samples) cannot be taken as an indication of 'sympathetic tone' in the whole individual. NA is rapidly removed from plasma, resulting in meaningless net veno-arterial concentration differences over organs unless its removal from arterial plasma is taken into account. In the forearm, for example, 40-50% of catecholamines are removed during one passage; about half of the NA in a venous sample is derived from the arm and half from the rest of the body. Therefore, conventional venous sampling overemphasizes local (mainly skeletal muscle) nerve activity. Whole-body sympathetic nerve activity may be monitored in arterial or mixed venous (i.e. pulmonary arterial) samples, which reflect NA overflow from all organs in the body. NA levels are determined both by overflow to plasma and clearance from plasma. NA turnover studies with 3H-NA infusions may be needed to assess clearance, but the simpler concentration measurements usually yield adequate information if the sampling site is relevant. NA overflow from an organ can be assessed (using 3H-NA or ADR as a marker for NA extraction in the organ) and provides valuable information on local sympathetic activity. Mental stress elicits marked circulatory responses, with mainly cardiorenal sympathetic activation and minor elevations of conventional venous plasma NA levels, thus illustrating the differentiated firing pattern of the sympathetic nerves. Circulating ADR is less important than neurogenic mechanisms in the responses to stress. Concentration-effect studies for infused catecholamines may be used for receptor sensitivity studies in vivo, but reflexogenic contributions to responses need to be determined. However, prejunctional mechanisms cannot be assessed without knowledge of the nerve activity present; for example, ADR infusion leads to increased nerve activity. When correctly sampled, measured and interpreted, plasma catecholamines can yield very valuable information on sympathoadrenal activity.

Sympathetic activity is influenced by task difficulty and stress perception during mental challenge in humans

1. Our aim was to determine the influence of the type of task, the absolute and relative difficulty of the task, and the perceived stress associated with performance of the task on sympathetic circulatory regulation during cognitive challenge in humans. 2. Sympathetic nerve activity to skeletal muscle (MSNA) determined from peroneal microneurography, heart rate and arterial blood pressure were recorded continuously in twelve subjects during a modified Stroop colour word test (CWT) and mental arithmetic (MA), each performed over six levels of increasing absolute task difficulty. Performance (percentage correct) on each task was assessed and ratings of perceived stress obtained. Responses to CWT and MA were compared at similar levels of performance and perceived stress. 3. MSNA decreased at task onset, remained below baseline levels at low levels of difficulty which were not perceived as stressful, increased above baseline levels at higher levels of difficulty which were perceived as stressful, and increased further during recovery. Thus, the regulation of MSNA was stress dependent. At similar levels of stress perception there were no differences in MSNA between CWT and MA. Although performance declined as task difficulty increased, there was no particular 'threshold' level of performance associated with the stimulation of MSNA. 4. Arterial pressure and heart rate were elevated above baseline levels throughout the mental tasks. Arterial pressure increased over the first 3-4 levels of each task and then plateaued whereas heart rate did not vary across increasing levels of task difficulty. Heart rate and arterial pressure responses to CWT were higher than those to MA. 5. These data demonstrate that during cognitive challenge the stimulation of MSNA is governed primarily by perceived stress which is dependent, in part, on the absolute level of task difficulty. In contrast, neither performance nor the type of cognitive task appear to be important determinants of MSNA. Arterial pressure is influenced by the task and level of difficulty. Heart rate is independent of task difficulty but may be task dependent.

Effects of mental stress on lipolysis in humans

Lipid mobilization was investigated in subcutaneous adipose tissue specimens obtained before and after a standardized mental-stress test in 14 non-obese healthy subjects. All participants responded with an increased heart rate and elevation of plasma glycerol levels. Plasma norepinephrine concentrations remained unchanged throughout the test. In six subjects, mental stress induced a significant increase in plasma epinephrine levels, to more than 0.26 nmol/L (responders), while the remaining eight individuals showed a response of less than 0.12 nmol/L (nonresponders). In the responders, a 30% increase in catecholamine-stimulated in vitro lipolysis was found after the mental-stress test, while the lipolytic response in isolated fat cells in vitro decreased slightly in the nonresponders after mental stress. A strong correlation (r = .84) was observed between the increased in vitro lipolytic responsiveness due to mental stress and circulating plasma epinephrine levels. In vitro data suggest that the augmentation in lipolytic activity induced by acute mental stress was caused by alterations between the beta-adrenoceptor and adenylate cyclase, ie, probably an increased coupling between beta-receptors and the stimulatory guanosine triphosphate [GTP]-binding protein (G2). This, in combination with elevated levels of circulating epinephrine, may explain the increased lipolysis during mental stress in some individuals (ie, responders). However, other parallel mechanisms for activation of lipolysis during mental stress must also exist in certain individuals (ie, nonresponders), and seem not to involve the adrenergic system.

Awareness of high blood pressure influences on psychological and sympathetic responses

The aim of the present study was to examine the effects of awareness of hypertension on psychological factors and whether there was an association between psychological and sympathetic responses. To avoid self-selection bias 32 19-yr old white men, all with mean blood pressure of 116 mm Hg were randomized into two groups. One group was informed that the blood pressure was elevated and asked to come to a second examination while the other was invited to take part in a coronary heart disease prevention program. A cold pressor test was undertaken and the subjects completed the Karolinska Scale of Personality (KSP). Assessed by the KSP, the informed group showed lower verbal aggression (p less than 0.01), irritability (p less than 0.05), monotony avoidance (p less than 0.05) and impulsiveness (p less than 0.05), higher detachment (p less than 0.05) but no significant differences in the other subscales like anxiety, psychasthenia or factors of hostility. Information significantly increased resting blood pressure and increments in heart rate and plasma adrenaline responses to cold pressor test. Thus, both psychological and sympathetic responses were influenced by awareness of high blood pressure. There were significant correlations between less assertive behaviour and increased plasma catecholamines.

Changes in injection-site blood flow and plasma free insulin concentrations in response to stress in type 1 diabetic patients

In order to test the effect of stress on injection-site blood flow and blood glucose control, 16 C-peptide negative patients were studied on a stress day, when a 30-min Stroop Colour-Word Test was completed, and a control day, when a cartoon was shown. Unmodified insulin was injected subcutaneously into the thigh before the test, and injection-site blood flow measured throughout the experiment with a thermal clearance probe. Blood glucose and plasma free insulin, glucagon, growth hormone, cortisol, and catecholamines were measured at intervals before, during, and after stress. Patients showed a significant overall rise in injection-site blood flow with the Stroop test from 4.1 (SD 1.6) to 5.2 (1.8) ml 100-g-1 min-1 (increase 38.1 (37.8) %, p less than 0.001). There was no overall significant difference between stress and control days in blood glucose or plasma free insulin levels, with differences in mean blood glucose levels during stress between the 2 days varying from -4.2 mmol l-1 to +6.3 mmol l-1 in individual patients. The increase in injection-site blood flow with stress correlated significantly with the increase in plasma free insulin concentration both during (r = 0.55) and after stress (r = 0.71). Differences in blood glucose concentration between stress and control day for each patient showed strong correlation with differences in plasma free insulin both during (r = -0.73) and after stress (r = -0.79). Differences in counter-regulatory hormones occurred but correlated poorly with blood glucose difference. Thus, stress affects the blood flow at the injection site, and this in turn affects insulin absorption. Most of the blood glucose response to stress is explained by changes in free insulin concentration.

Salivary secretion rate, yeast cells, and oral candidiasis in patients with acute leukemia

Stimulated salivary secretion rate was repeatedly determined in 29 patients with acute leukemia during two periods of cytotoxic treatment in myelosuppressive doses. For comparison, the salivary secretion rate was studied in 83 healthy persons and in three other groups of hospitalized patients without malignant disorders. At the start of cytotoxic treatment the secretion rate in the patients with leukemia was lower than in healthy persons. The rate fell significantly after 1 to 3 days and later rose to the level seen in the healthy persons. Several interacting factors may have contributed to the decrease in salivary secretion rate, but the most important factor was probably the use of antiemetic drugs during the first 3 days of the study periods. No relationship was found between salivary secretion rate and the number of gram-negative rods found in the mouth. Patients with low salivary secretion rates had high numbers of yeast cells and more often oral candidiasis.

Individual Differences in Cellular Immune Response to Stress

Correlational studies suggest that psychological stress suppresses cellular immune function in some, but not all, individuals. Here, effects of acute mental stress on lymphocyte subpopulations and T-lymphocyte mitogenesis were examined experimentally in healthy young adults. CD8 (T-suppressor/cytotoxic) lymphocytes increased in number and T-cell response to stimulation by phytohemagglutinin was attenuated following exposure to a 20-min laboratory stressor, but only in persons who also showed heightened catecholamine and cardiovascular reactions to stress. Hence, individuals differ substantially in their immunologic responsivity to behavioral stimuli, and such differences parallel (and may be predicted by) interindividual variability in stress-induced sympathetic nervous system activation.

Biological correlates of mental stress related to anticipated caesarean section

The relationships between self-reported assessments of acute anxiety and several biochemical and physiological indicators of stress reaction were investigated in pregnant women at term in connection with spinal analgesia for caesarean section. Fear and apprehension were statistically significantly associated only with blood pressure and with an increase in heart rate from the previous day. The subjective estimate of the quality of the preoperative night's sleep was negatively associated with biochemical plasma and cerebrospinal fluid (CSF) measures of sympatho-adrenal activity. The previously reported negative correlation between body height and 5-hydroxyindoleacetic acid (5-HIAA, an indicator of serotonin metabolism) in lumbar CSF was confirmed. The concentration of 5-HIAA in CSF was positively correlated with the levels of other acidic monoamine metabolites and cortisol in CSF. It is concluded that hormone and monoamine metabolite measurements in CSF and plasma have only limited usefulness as quantitative indicators of the intensity of preoperative fear and anxiety.

Correlations between psychological and physiological responses to acute flight phobia stress

Exposure of phobic subjects to real-life psychological stress may induce a high level of anxiety and be better than laboratory experiments for studies of physiological responses to psychological stress in human research. Therefore, by introducing natural psychological stress, i.e. actual flying in subjects with flight phobia (n = 23), the present study aimed at testing the hypothesis that there is, during mental stress, a direct relationship between the level of anxiety and the responses in the physiological variables blood pressure, heart rate and plasma catecholamines. Plasma adrenaline, heart rate, blood pressure and perceived anxiety measured by three different scales increased highly significantly during flight whereas plasma noradrenaline did not change. No direct relationship was found between the physiological and psychological variables. Thus, the physiological responses to natural psychological stress in terms of phobic anxiety may be definite, but the way the responses are related is less clear.

Generalized anxiety disorder: some biochemical aspects

Fifty-one patients who met DSM-III criteria for generalized anxiety disorder, and who were recruited to participate in a drug outcome study, filled out a variety of rating scales and had blood samples drawn for plasma norepinephrine, epinephrine, and free 3-methoxy-4-hydroxyphenylglycol (MHPG) after a 20-min rest period. This group was compared to 15 normal controls who also had their blood drawn after a 20-min rest period. While the two groups were initially found to have significantly different levels of plasma free MHPG through the use of t tests, this finding was not confirmed by subsequent discriminant analysis.

Muscle sympathetic activity and norepinephrine release during mental challenge in humans

Muscle sympathetic nerve activity (MSA; peroneal nerve) and arterial and femoral venous plasma norepinephrine (NE) were studied in 10 volunteers at rest, during a relaxation procedure (RELAX), and during two mental challenges, a word identification test (WIT) and a color word test (CWT). [3H]NE infusions were used to assess NE spillover to and clearance from plasma. Net NE overflow from the leg was calculated. RELAX reduced MSA and femoral venous NE concentrations. CWT increased blood pressure, cardiac output (thermodilution), and calf flow and reduced systemic vascular resistance. Responses to WIT were less marked. CWT increased MSA by 25%, femoral venous NE concentrations by 25%, and NE overflow from the leg by 26% at 3 min. Fractional epinephrine and [3H]NE extractions were flow related and decreased during CWT. The arterial contribution to femoral venous NE (about half) increased by 10% during CWT. Arterial NE levels and spillover increased, but NE clearance was unchanged. Femoral venous NE concentrations and NE spillover (not based on flow measurements) and regional NE overflow correlated with MSA. Thus NE concentrations in plasma reflect spillover rather than clearance at rest and during mental challenge. Biochemical and neurophysiological indexes of sympathetic activity correlate when assessed in the same region. Mental stress increases sympathetic activity in leg muscle.

Mechanisms of hypertension during and after orthotopic liver transplantation in children

The aim of this study was to assess the hormonal alterations that may mediate the systemic hypertension that develops in patients during the perioperative period of orthotopic liver transplantation. We studied nine pediatric patients without previous hypertension or renal disease during six time points, starting before transplantation and ending at 48 hours after surgery. Hypertension developed in all patients in association with central venous pressures less than 10 mm Hg. Free water clearance was negative in all nine patients. Vasopressin levels increased intraoperatively but fell as hypertension developed. Atrial natriuretic factor levels increased as systemic blood pressure rose. A high level of plasma renin activity was observed in four patients with renal insufficiency. In six patients, postoperative 24-hour urinary norepinephrine excretion was within the normal age-adjusted range. These findings suggest that the combination of cyclosporine, corticosteroids, and, in some patients, an elevated plasma renin activity prevents the kidney from responding to the acute volume and salt overload with an appropriate diuresis and natriuresis, thus leading to systemic hypertension. The treatment of hypertension after liver transplantation may include salt restriction, diuretics, and, in those patients with a low creatinine excretion index, angiotensin coverting enzyme inhibitors.

Biogenic amines and their metabolites in body fluids of normal, psychiatric and neurological subjects

The biogenic monoamines and their metabolites have been isolated, identified and quantified in human body fluids over the past forty years using a wide variety of chromatographic separation and detection techniques. This review summarizes the results of those studies on normal, psychiatric and neurological subjects. Tables of normal values and the methods used to obtain them should prove to be useful as a reference source for benchmark amine and metabolite concentrations and for successful analytical procedures for their chromatographic separation, detection and quantification. Summaries of the often contradictory results of the application of these methods to psychiatric and neurological problems are presented and may assist in the assessment of the validity of the results of experiments in this field. Finally, the individual, environmental and the methodological factors affecting the concentrations of the amines and their metabolites are discussed.

[The kinetics of plasma catecholamine in alkylphosphate poisoning and their therapy]

In connection with the "endogenous acetylcholine-poisoning" due to organophosphorous compounds beside the clinical important muscarinic and nicotinic symptoms an activation of the sympathetic nervous system (adrenal medulla, sympathetic ganglia) is expected. Therefore a kinetic profile of norepinephrine and epinephrine in the plasma of two patients with severe parathion-poisonings was taken up through the whole period of the intensive-medical treatment. The method used was HPLC with electrochemical detection. The parathion-concentration of the same plasma samples were measured, too. The result were individual different courses with periodically appearing, markedly increased plasma catecholamine values. A direct correlation of catecholamines with the parathion-concentration was not recognizable. A possible influence of the atropine-treatment as well as of stress-factors is discussed but estimated as not responsible for the observed peaks.

Effect of ethanol and stress on plasma catecholamines and their relation to changes in emotional state and performance

The "tension reduction hypothesis" of ethanol was investigated with respect to stress- and ethanol-induced changes of plasma catecholamines and their relations to changes in emotional state and performance. Twenty-two healthy male volunteers were tested under the influence of 0.8 g/kg ethanol and compared to 22 matched controls receiving a placebo drink. Stress was induced by mental arithmetic applied prior to and 45 min after fluid consumption. Plasma epinephrine (E) and norepinephrine (NE) obtained from an indwelling cannula inserted 50 min prior to stress application were determined prior to and after each stress session. Percentage changes were compared within and between groups and correlated with respective changes of emotional states and performance in mental arithmetic. While ethanol decreased performance and stress-related emotional arousal, it did not affect stress-induced changes in plasma catecholamines. Rather, the fluid (ethanol as well as placebo) increased NE levels. Emotional tension reduction was associated with low resting or average levels of E in the placebo group but this relationship was disrupted by ethanol. High NE resting levels and drink induced increases predicted emotional tension reduction with placebo but an increase in stress induced depression with alcohol. "Biochemical tension reduction" (represented by both reduced E and NE stress response) may be predicted from generally lower levels of activation and elation by alcohol but not with the placebo condition. Although performance was positively related to low NE resting levels and stress responses, no influence of alcohol on this relationship was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiovascular reactivity and plasma prolactin response to mental stress in normals and hypertensives

Central dopaminergic activity (CDA) may be involved in blood pressure control as a negative modulator of sympathetic outflow. In this study the plasma PRL changes produced by mental stress (a colour-word conflict test, CWT) were investigated in normals (NT, n.15) and stable hypertensives (HT, n.16) and the PRL response, as a possible index of CDA was correlated to the cardiovascular and the plasma renin activity (PRA) responses as indexes of peripheral sympathetic outflow. A significant (p less than 0.05) slight decrease in mean values of PRL was observed in normals after the CWT but no change was found in hypertensives. No correlation was found between the PRL responses to CWT and the maximal mean arterial pressure changes or the PRA changes whether the groups were considered separately or together. These findings indicates that PRL does not appear to be a reliable index of the CDA involved in blood pressure control.

Characterization of stress reactions to the Stroop Color Word Test

Sympatho-adrenal activation induced by stress contributes to the development of pathological states such as hypertension and anxiety disorders. The Stroop Color Word Test (CWT) is evaluated as a test for the study of stress-induced sympathetic effects, on the basis of psychological, physiological and biochemical responses. The CWT induced increases in plasma and urinary adrenaline, heart rate, respiration rate, electrodermal activity, electromyography, feelings of anxiety, and decreased finger pulse amplitude.