Biomedical subjects

K C Light

Publications and source records attributed to K C Light.

At least 37 records · Page 2Linked to original sources

PubMed1998

Heart rate variability at rest and during mental stress in patients with coronary artery disease: differences in patients with high and low depression scores.

This study tested the hypothesis that coronary artery disease (CAD) patients with high depressed mood scores differ in sympatho-vagal balance during mental stress compared to patients with low depressed mood scores. Using electrocardiographic monitoring, heart variability data from spectral analysis and hemodynamic parameters were obtained prior to and during mental stress from 34 men and 7 women. A public speaking task was used as the mental stressor. Patients were grouped by a median split of their Minnesota Multiphasic Personality Inventory-Depression score. During mental stress, patients with higher depression scores had greater changes in peak heart rate (p < .05) and low frequency to high frequency power ratio (p < 0.05) than patients with lower scores suggesting a shift toward more sympathetic activity during mental stress. These findings may be related to the reported relation between depression and survival risk in patients with CAD.

Journal Article↗

PubMed1997

Ten-year stability of cardiovascular responses to laboratory stressors.

In this study, we examined test-retest stability of cardiovascular stress responses over a decade of the life span. Participants were 55 male college undergraduates, 19 years of age at initial testing, and 29 years of age at follow-up testing. Stressors were a foot cold pressor and an aversive reaction time task. Cardiovascular measures included systolic and diastolic blood pressure, heart rate, and preejection period. For cold pressor, the magnitude and pattern of cardiovascular responses remained unchanged at the 10-year follow-up. For the reaction time task, the characteristic cardiovascular response patterns was preserved but with significant attenuation of magnitude. The present findings are consistent with previous observations of temporal stability but over a substantially longer test-retest interval. The long-term stability of stress responses is discussed in the context of stress test methodology, behavioral response demands, and maturation of the physiological systems involved in cardiovascular response expression.

Adolescent↗

PubMed1997

Blood pressure, gender, and parental hypertension are factors in baseline and poststress pain sensitivity in normotensive adults.

We studied 38 men and 36 women to learn whether a brief speech stressor reduced normotensive humans' thermal pain sensitivity, whether baseline and poststress pain threshold and tolerance varied with blood pressure (BP) and hemodynamic measures, and whether these relations differed by gender and parental hypertension (PH). PH-women with low-resting BPs had lower baseline pain tolerance than did all the other groups (ps <.05), and this group alone exhibited stress-induced analgesia (p = .008). In women, pre- and poststress pain tolerance varied directly with rest and stress BP (ps <.05).

Journal Article↗

PubMed1996

Ischemic, hemodynamic, and neurohormonal responses to mental and exercise stress. Experience from the Psychophysiological Investigations of Myocardial Ischemia Study (PIMI).

BACKGROUND: The pathophysiology of mental stress-induced myocardial ischemia, which occurs at lower heart rates than during physical stress, is not well understood. METHODS AND RESULTS: The Psychophysiological Investigations of Myocardial Ischemia Study (PIMI) evaluated the physiological and neuroendocrine functioning in unmedicated patients with stable coronary artery disease and exercise-induced ischemia. Hemodynamic and neurohormonal responses to bicycle exercise, public speaking, and the Stroop test were measured by radionuclide ventriculography, ECG, and blood pressure and catecholamine monitoring. With mental stress, there were increases in heart rate, systolic blood pressure, cardiac output, and systemic vascular resistance that were correlated with increases in plasma epinephrine. During exercise, systemic vascular resistance fell, and there was no relationship between the hemodynamic changes and epinephrine levels. The fall in ejection fraction was greater with mental stress than exercise. During mental stress, the changes in ejection fraction were inversely correlated with the changes in systemic vascular resistance. Evidence for myocardial ischemia was present in 92% of patients during bicycle exercise and in 58% of patients during mental stress. Greater increases in plasma epinephrine and norepinephrine occurred with ischemia during exercise, and greater increases in systemic vascular resistance occurred with ischemia during mental stress. CONCLUSIONS: Mental stress-induced myocardial ischemia is associated with a significant increase in systemic vascular resistance and a relatively minor increase in heart rate and rate-pressure product compared with ischemia induced by exercise. These hemodynamic responses to mental stress can be mediated by the adrenal secretion of epinephrine. The pathophysiological mechanism involved are important in the understanding of the etiology of myocardial ischemia and perhaps in the selection of appropriate anti-ischemic therapy.

Adult↗

PubMed1996

Ethnic differences in forearm vasodilator capacity.

Previous studies have demonstrated significant ethnic differences in left ventricular structure in both normotensive and hypertensive subjects. To determine if these differences in ventricular geometry are associated with differences in vascular structure, we measured the minimum forearm vascular resistance in 30 healthy young African-American adults and in 30 whites matched for age, gender, and blood pressure. Average daytime blood pressure was determined by ambulatory monitoring during a typical work day. Minimum forearm vascular resistance was measured by plethysmography after 10 minutes of forearm ischemia. Indexed left ventricular mass and relative wall thickness were measured by 2-dimensional-directed M-mode echocardiography. The mean (+/-SD) ambulatory pressure was 126 +/- 11/79 +/- 8 mm Hg in African-Americans and 126 +/- 11/79 +/- 7 mm Hg in whites. The 2 groups were similar in body mass index and in family history of hypertension. African-Americans had a higher minimum forearm vascular resistance than did whites (2.39 +/- 0.75 vs 2.03 +/- 0.55 mm Hg, p <0.05). There was a trend toward a greater left ventricular relative wall thickness in African-Americans (0.38 +/- 0.07 vs 0.35 +/- 0.06, p=0.09). These results suggest that early vascular remodeling is present in African-Americans who do not have established hypertension, and that this ethnic difference in vascular structure is associated with a difference in ventricular geometry.

Adult↗

PubMed1996

Acute aerobic exercise reduces ambulatory blood pressure in borderline hypertensive men and women.

Ambulatory blood pressure (BP) monitoring was undertaken on two days in 31 men and women (11 with elevated resting and ambulatory BP and 20 who were normotensive), once following each of these treatment conditions: 20 min of moderate aerobic bicycle ergometry, and an equivalent control rest period. The two monitoring days were conducted within a 72 h period with the order of treatments counterbalanced across subjects. Mean BP and heart rate (HR) levels were calculated for each individual on an hourly basis and for work, home, and sleep periods, In the elevated BP group, the exercise day compared to the control day was associated with lower BP at work. Hour-by-hour analyses confirmed that the BP-lowering effect of exercise was significant for 5 h and diminished in magnitude between hours 6 and 9. These effects were not attributable to any marked differences in mood, total daily stress, posture, or activities between test days. Exercise was not associated with any appreciable differences in sleep BP or in the 24-h HR profile No differences in BP or HR as a function of exercise were seen in the normotensive group; however, the exercise-induced reduction in mean arterial BP (MAP) for hours 2 through 5 was significantly positively correlated with control day MAP levels at work in the total sample. Thus, moderate aerobic exercise, when engaged in prior to the stresses of daily living, seems to confer a protective reduction in ambulatory BP, particularly in individuals with elevated BP.

Adult↗

PubMed1996

Relationship among depression scores, beta-endorphin, and angina pectoris during exercise in patients with coronary artery disease.

OBJECTIVES: To determine the relationship between depression scores and (1) anginal indices during exercise including time to onset of angina, duration of angina, and severity of angina and (2) beta-endorphin at rest and in response to exercise. DESIGN: Prospective clinical trial. SETTING: Tertiary-care university hospital. PATIENTS: Fifty-eight patients with documented coronary artery disease and exercise-induced ischemia. OUTCOME MEASURES: Anginal indices during exercise (time to onset of angina, duration of angina, severity of angina); hemodynamic measures (systolic blood pressure, heart rate, rate pressure product) at rest, at onset of angina and at peak exercise; and plasma beta-endorphin levels at rest and immediately after exercise. RESULTS: Twenty-two of 58 patients had typical angina and electrocardiographic change indicating myocardial ischemia during exercise. There was a positive correlation between depression scores and duration of angina and a negative correlation between depression scores and time to onset of angina. Among patients with angina during exercise, systolic blood pressure increased to a greater extent in patients with high depression scores. Patients with high depression scores had higher resting beta-endorphin levels. CONCLUSIONS: Patients with depressed mood had greater perception of anginal pain than nondepressed patients, which cannot be explained by differences in the severity of ischemia. Possible mechanisms include an alteration in beta-endorphin regulation or differences in baroreceptor stimulation.

Adult↗

PubMed1996

Social support and hostility interact to influence clinic, work, and home blood pressure in black and white men and women.

The effects of hostility and social support on clinic, work, and home systolic (SBP) and diastolic (DBP) blood pressures were evaluated in 129 healthy adults. High hostility was related to higher SBP and DBP in Whites; low hostility was related to higher SBP and DBP in Blacks. These relationships were significant for men at home and at work and for women at screening. The relationship between low hostility and higher BP in Blacks was largely due to Black men who reported low hostility plus high anger-in (suggesting suppressed hostility). In contrast, high hostile Black men with high tangible support tended to exhibit lower BP than all other Black men. In White women, high belonging support was related to lower BP, independent of hostility, and low tangible support plus high hostility was related to higher clinic BP. In high hostile subjects, regardless of ethnicity or gender, high appraisal support was related to lower overall BP. These data suggest that the adverse BP effects of hostility and the beneficial effects of social support interact in a complex manner, reflecting contextual, ethnic, and gender specificities.

Adult↗

PubMed1996

Blood pressure publication guidelines. Society for Psychophysical Research.

Blood pressure is one of the most commonly recorded functions in physiology and medicine, and it has become a major variable in recent psychophysiological and behavioral medicine research. Many methods have been developed for the measurement of blood pressure in clinical, laboratory, and natural settings. The broad objectives of this report are to summarize the most critical methodological issues in the measurement of blood pressure and to present principles and recommendations for the evaluation of blood pressure methods and findings in published studies.

Blood Pressure↗

PubMed1996

The ability of active versus passive coping tasks to predict future blood pressure levels in normotensive men and women.

Casual blood pressure (BP) after a 2-year follow-up interval was determined in 40 normotensive men and women (20 Blacks and 20 Whites), who had been initially tested for cardiovascular responses to a variety of active and passive coping tasks, including active speech, passive speech, reaction time, and forehead cold pressor tasks. Stepwise multiple regression analyses were used to identify the best model for predicting follow-up BP. Average systolic blood pressure (SBP) level during cold pressor stress was the single most powerful predictor of casual SBP over 2 years even after controlling for initial resting SBP. Other predictors of follow-up SBP were initial SBP, parental history of hypertension, and heart rate and SBP during passive speech (final model R(2) = .78). For follow-up diastolic blood pressure (DBP), the only significant predictors were initial DBP and male gender. These results contribute to a growing body of literature that suggests that cardiovascular measures observed during stressors have predictive validity above and beyond that of traditional predictor variables.

Journal Article↗

PubMed1995

Increased heart rate response to laboratory-induced mental stress predicts frequency and duration of daily life ambulatory myocardial ischemia in patients with coronary artery disease.

This study assessed the relation between hemodynamic data during a standardized mental stressor and ambulatory ischemia to determine if laboratory-induced responses could predict the magnitude of daily life ischemia. Forty-two men and 11 women, aged 46 to 79 years (mean 61), with coronary artery disease and exercise-induced ischemia were studied. All patients underwent 24- to 48-hour ambulatory electrocardiographic (ECG) monitoring (mean 43 +/- 0.8 hours) and laboratory-induced mental stress using a public speaking task. Hemodynamic data were obtained at rest and every minute during mental stress. Thirty-three of 53 patients (62%) had at least 1 ischemic episode during ECG monitoring. In patients who had ambulatory ischemia, there was a mean number of 7.9 +/- 1.8 episodes (mean total duration 79.2 +/- 24.1 minutes/48 hours). Significant positive correlations were found for peak heart rate and changes in heart rate during mental stress and ambulatory ischemia (r = 0.353 to 0.462, p < 0.05) in patients who had ambulatory ischemia. There was no correlation between systolic blood pressure during mental stress and ambulatory ischemia. Results of this study demonstrate that heart rate response during laboratory-induced mental stress correlates with magnitude of ischemia on ambulatory ECG monitoring in patients with coronary artery disease.

Activities of Daily Living↗

PubMed1995

Thyroid axis function during the menstrual cycle in women with premenstrual syndrome.

Fifteen women with premenstrual syndrome (PMS) and 15 control women were tested twice for thyroid axis measures, once during the follicular and once during the luteal phase of the menstrual cycle. While PMS and control women did not differ in mean hormone values during either phase of the menstrual cycle, PMS women showed significantly greater variability in hormone measures including TSH, T3 uptake, T4, and FTI relative to controls. These findings are consistent with the conceptualization that, for a subset of women with PMS, thyroid axis abnormalities may contribute to their disorder. Additionally, when analyzed in the sample as a whole, the menstrual cycle exerted a significant effect on reverse T3 with greater levels observed in the luteal relative to the follicular phase of the cycle.

Adult↗

PubMed1995

Psychophysical responses to a speech stressor: correlation of plasma beta-endorphin levels at rest and after psychological stress with thermally measured pain threshold in patients with coronary artery disease.

OBJECTIVES: We tested the hypothesis that psychological stress alters plasma levels of opioid peptides and that these plasma levels are related to pain perception in patients with coronary artery disease. BACKGROUND: Public speaking psychological stress has previously been shown to be associated with silent ischemia. METHODS: After instrumentation and a 30-min rest period, venous blood samples for beta-endorphin were obtained before and immediately after psychological stress in 20 patients with coronary artery disease. Pain threshold was then assessed using a thermal probe technique at baseline and immediately after stress. Patients gave three brief speeches lasting a total of 15 min about real-life hassle situations. RESULTS: Psychological stress significantly increases plasma beta-endorphin levels (4.3 +/- 0.9 pmol/liter [mean +/- SE] at rest to 8.3 +/- 2 pmol/liter after stress, p < 0.05). There was a significant positive correlation between pain threshold and beta-endorphin levels after stress (r = 0.577, p = 0.008). This significant positive correlation was still present while rest blood pressure and change in blood pressure during stress were controlled for by analysis of covariance techniques. CONCLUSIONS: In patients with coronary artery disease and exercise-induced ischemia, public speaking produces psychological stress manifested by increased cardiovascular reactivity and causes an increase in plasma beta-endorphin levels that is significantly correlated with pain thresholds. These findings may explain the predominance of silent ischemia during psychological stress in patients with coronary artery disease.

Blood Pressure↗

PubMed1995

Patients with borderline elevated blood pressure have enhanced left ventricular contractility.

Recent analyses of midwall left ventricular mechanics have demonstrated that patients with established hypertension and ventricular hypertrophy have depressed myocardial contractility. In this study, myocardial performance was assessed in subjects with borderline blood pressure elevations by relating the velocity of circumferential midwall fiber shortening to end-systolic stress in young men and women who were classified as normotensive (n = 92) or as having marginally elevated blood pressure (n = 43) based on daytime ambulatory systolic blood pressure. On average, velocity of midwall fiber shortening in those with higher blood pressure was 8% greater than predicted from results of normotensive controls. These results suggest that young patients with borderline blood pressure elevations have enhanced left ventricular contractility.

Adult↗

PubMed1995

Physiological determinants of hyperreactivity to stress in borderline hypertension.

Blood pressure hyperreactivity during stress is characteristic of borderline hypertension in white men. The present study evaluated the hemodynamic basis of this hyperreactivity and assessed its physiological basis in terms of sympathetic nervous system function. Cardiovascular adjustments to an aversive reaction time test were compared with those of the forehead cold pressor test, representing stressors that elicit active behavioral responses in contrast to passive tolerance of aversive stimulation. As anticipated, blood pressure increases were greater in 12 borderline hypertensive men compared with 21 age-matched normotensive men during the active reaction time stressor but not during the passive cold pressor test. The pressor hyperreactivity in borderline hypertensives was associated with excessive rises in plasma epinephrine and norepinephrine, leading to greater increases in cardiac output, despite evidence that the cardiac beta-adrenergic receptors in these subjects were downregulated compared with those of normotensive subjects. During the cold pressor test, borderline hypertension was associated with greater increases in systemic vascular resistance, which, in the presence of normal baroreceptor reflex function, led to an attenuation of cardiac output, thus producing no greater net effect on blood pressure than seen in normotensive subjects. Evidence of vascular hypertrophy in the borderline hypertensive subjects was considered to account for their vascular hyperreactivity to cold pressor stimulation. Collectively, the observations in this study further support the view that the early stages of hypertension in white men are characterized by sympathetic nervous system hyperreactivity, but only in association with tasks that elicit active behavioral coping responses.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗

PubMed1995

Job status and high-effort coping influence work blood pressure in women and blacks.

Work-related stress has been associated with an increased risk of hypertension and more severe cardiovascular problems in white men but has been less studied in women and black men. To determine whether the trait of high-effort coping (John Henryism) was related to higher blood pressure during work and laboratory challenges, we studied a biracial sample of 72 men and 71 women working full time outside the home who underwent ambulatory blood pressure monitoring for one 8-hour workday. This was followed by laboratory monitoring of blood pressure during resting baseline and five brief stressors. Women who were high-effort copers and had high status jobs had higher diastolic pressures at work and in the lab than other women; their pressure levels did not differ from those of men, but other women had lower pressures than men. In blacks, the same combination of high-effort coping plus high job status was similarly associated with high work and laboratory diastolic pressure, as well as higher work systolic pressure. The trait of high-effort coping was observed in the large majority (71%) of the women and blacks who had achieved high status jobs but was seen in a minority (36%) of white men with high status jobs and was unrelated to increased blood pressure in the latter group.

Adaptation, Psychological↗

PubMed1995

Parental history of hypertension and cardiovascular response to stress in Black and White men.

White offspring of hypertensives typically exhibit an elevated cardiovascular response to stress. Studies of Black offspring of hypertensives have been fewer, with inconsistent results. This may be due, in part. to incomplete characterizations of hemodynamic responses. This study examines cardiovascular reactivity in Black and White offspring of hypertensives with a particular focus on vascular resistance responses. A total of 62 healthy normotensive men, 41 with a parental history of hypertension (PH+: 21 Blacks, 20 Whites), and 21 without parental hypertension (PH-: 7 Blacks, 14 Whites) engaged in a series of laboratory tasks. Both Black and White PH+ participants exhibited elevated diastolic blood pressure (DBP) responses, but to different patterns of stressor tasks. Familial differences in total peripheral resistance response were also obtained for Black and White participants in a comparison across all tasks, but were particularly evident in tasks when PH+ participants had elevated DBP responses. These results suggest that a parental history of hypertension is an important moderator of cardiovascular, and in particular peripheral vascular, responses to stress in Black and White individuals.

Journal Article↗

PubMed1994

Intertask consistency of hemodynamic responses to laboratory stressors in a biracial sample of men and women.

Cardiovascular responses were examined in a community sample of 128 subjects, comprised of 58 African American and 70 Caucasian American men and women. Subjects completed a battery of laboratory stressors including mental arithmetic, reaction time, a speech task, and the cold pressor test. In addition to systolic and diastolic blood pressures, the underlying hemodynamic parameters of cardiac output and total peripheral resistance were assessed. In order to explore intertask consistency of response in both ethnic groups and both gender groups, correlational analyses were conducted separately for each group. For the psychological tasks, unanimously significant coefficients were observed. Intertask consistency between psychological tasks and the cold pressor was also considerable, but was somewhat less impressive (particularly for blood pressure) than that observed among the psychological tasks themselves. With regard to hemodynamic responses, cardiac output and total peripheral resistance demonstrated intertask consistency equal to, if not greater than, that shown by systolic and diastolic blood pressure, this consistency being evident for each ethnic and each gender group.

Adolescent↗