Urinary Norepinephrine Is a Metabolic Determinant of 24-Hour Energy Expenditure and Sleeping Metabolic Rate in Adult Humans.

BACKGROUND: Interindividual variability in 24-hour energy expenditure (24EE) during energy-balance conditions is mainly determined by differences in body composition and demographic factors. Previous studies suggested that 24EE might also be influenced by sympathetic nervous system activity via catecholamine (norepinephrine, epinephrine) secretion. Therefore, we analyzed the association between catecholamines and energy expenditure in 202 individuals from a heterogeneous population of mixed ethnicities. METHODS: Participants (n = 202, 33% female, 14% black, 32% white, 41% Native American, 11% Hispanic, age: 36.9 ±â€…10.3 y [mean ±â€…SD], percentage body fat: 30.3 ±â€…9.4) resided in a whole-room calorimeter over 24 hours during carefully controlled energy-balance conditions to measure 24EE and its components: sleeping metabolic rate (SMR), awake-fed thermogenesis (AFT), and spontaneous physical activity (SPA). Urine samples were collected, and 24-h urinary epinephrine and norepinephrine excretion rates were assessed by high-performance liquid chromatography. RESULTS: Both catecholamines were associated with 24EE and SMR (norepinephrine: +27 and +19 kcal/d per 10 µg/24h; epinephrine: +18 and +10 kcal/d per 1 µg/24h) in separate analyses after adjustment for age, sex, ethnicity, fat mass, fat-free mass, calorimeter room, temperature, and physical activity. In a multivariate model including both norepinephrine and epinephrine, only norepinephrine was independently associated with both 24EE and SMR (both P < .008), whereas epinephrine became insignificant. Neither epinephrine nor norepinephrine were associated with adjusted AFT (both P = .37) but epinephrine was associated with adjusted SPA (+0.5% per 1 µg/24h). CONCLUSIONS: Our data provide compelling evidence that sympathetic nervous system activity, mediated via norepinephrine, is a determinant of human energy expenditure during nonstressed, eucaloric conditions.

[Assessment of the perioperative factors contributing to the hemodynamic changes during surgery in ten patients with pheochromocytoma].

BACKGROUND: Intensive perioperative management is required for adrenalectomy in patients with pheocromocytoma because of the unstable hemodynamics and life threatening cardiovascular disturbances due to catecholamine surge from the neuroendocrine tumors. The aim of this study was to assess the perioperative factors contributing to the hemodynamic changes during surgery in pheochromocytoma. METHODS: Ten patients with pheochromocytoma undergoing elective adrenalectomy were enrolled in this retrospective study. The circulating blood volume before surgery and the perioperative factors associated with hemodynamic changes during surgery were assessd by the pulse dye densitometry and VigileoTM/ FroTracTM system, respectively. RESULTS: The decreases of blood pressure after resections of the central veins from tumors were significantly greater in laparotomy than those in laparoscopic surgery (P<0.05). In addition, the decreases of blood pressure after resection of the central were correlated with tumor sizes (R= -0.611), perioperative noradrenaline (NA) blood levels (R= -0.860), perioperative amounts of NA in urine (R= -0.743), and mean stroke volume variations for 5 min after resection of the veins(R= - 0.679). CONCLUSIONS: The decreases of blood pressure after resections of the central veins are dependent on the perioperative blood NA levels, the level of NA in the perioperative urine testig, and tumor sizes.

Behavioral and perceived stressor effects on urinary catecholamine excretion in adult Samoans.

OBJECTIVES: The effects of perceptions and behaviors related to culturally patterned socioeconomic obligations on catecholamine excretion rates were studied in a cross-sectional sample of Samoan adults. METHODS: A total of 378 participants, ages 29-62 years, from 9 villages throughout Samoa, provided timed overnight urine specimens, and self-reported perceptions and behaviors associated with contributions to one's family, aiga, and chief, matai, and communal gift exchanges, fa'alavelave. Urinary norepinephrine and epinephrine excretion rates were measured by high performance liquid chromatography with electrochemical detection. Age (≤40 vs. >40 years) and gender-specific regression models were estimated to detect associations with catecholamine excretion. RESULTS: Young women who contribute more to their matai, who consider fa'alavelave to be a financial strain, and who view their contribution to their matai to be "just right," had significantly higher residence-adjusted norepinephrine excretion. Young women who contribute more to their matai, who consider fa'alavelave to be a financial strain, and who consider their contribution to their aiga not to be a burden, had higher epinephrine excretion. Older men who contribute more to their aiga and who perceive their contribution to their aiga to be "just right" had increased residence-adjusted epinephrine excretion. CONCLUSIONS: Individual-level perceptions and behaviors related to traditional socioeconomic obligations are a significant correlate of increased overnight catecholamine excretion rates. Higher excretion rates may be attributed to psychosocial stress arousal associated with a discordance between personal desires for upward social mobility, and family and community-based socioeconomic obligations. Changes in patterns of individual-level psychosocial stress arousal may contribute to cardiovascular disease risk in modernizing Samoans.

Minimal changes in environmental temperature result in a significant increase in energy expenditure and changes in the hormonal homeostasis in healthy adults.

OBJECTIVE: Resting energy expenditure (EE) is a major contributor to the total EE and thus plays an important role in body weight regulation. Adaptive thermogenesis is a major component of EE in rodents, but little is known on the effects of exposure of humans to mild and sustainable reduction in environmental temperature. DESIGN: To characterize the dynamic changes in continuously measured resting EE, substrate utilization, and hormonal axes simultaneously in response to mild reduction in environmental temperature, we performed a cross-over intervention. METHODS: Twenty-five volunteers underwent two 12-h recordings of EE in whole room indirect calorimeters at 24 and 19 °C with simultaneous measurement of spontaneous movements and hormonal axes. RESULTS: Exposure to 19 °C resulted in an increase in plasma and urine norepinephrine levels (P<0.0001), and a 5.96% (P<0.001) increase in EE without significant changes in spontaneous physical activity. Exposure to the lower temperature resulted in a significant increase in free fatty acid levels (P<0.01), fasting insulin levels (P<0.05), and a marginal decrease in postprandial glucose levels. A small but significant (P<0.002) increase in serum free thyroxine and urinary free cortisol (P<0.05) was observed at 19 °C. CONCLUSIONS: Our observations indicate that exposure to 19 °C, a mild and tolerable cold temperature, results in a predictable increase in EE driven by a sustained rise in catecholamine and the activation of counter-regulatory mechanisms.

C-type natriuretic peptide as a new regulator of food intake and energy expenditure.

The physiological implication of C-type natriuretic peptide (CNP) including energy metabolism has not been elucidated, because of markedly short stature in CNP-null mice. In the present study we analyzed food intake and energy expenditure of CNP-null mice with chondrocyte-targeted CNP expression (CNP-Tg/Nppc(-/-) mice), in which marked skeletal dysplasia was rescued, to investigate the significance of CNP under minimal influences of skeletal phenotypes. In CNP-Tg/Nppc(-/-) mice, body weight and body fat ratio were reduced by 24% and 32%, respectively, at 20 wk of age, and decreases of blood glucose levels during insulin tolerance tests were 2-fold exaggerated at 17 wk of age, as compared with CNP-Tg/Nppc(+/+) mice. Urinary noradrenalin excretion of CNP-Tg/Nppc(-/-) mice was greater than that of CNP-Tg/Nppc(+/+) mice by 28%. In CNP-Tg/Nppc(-/-) mice, rectal temperature at 1600 h was higher by 1.1 C, and uncoupling protein-1 mRNA expression in the brown adipose tissue was 2-fold increased, which was canceled by propranolol administration, as compared with CNP-Tg/Nppc(+/+) mice. Oxygen consumption was significantly increased in CNP-Tg/Nppc(-/-) mice compared with that in CNP-Tg/Nppc(+/+) mice. Food intake of CNP-Tg/Nppc(-/-) mice upon ad libitum feeding and refeeding after 48 h starvation were reduced by 21% and 61%, respectively, as compared with CNP-Tg/Nppc(+/+) mice. This study unveiled a new aspect of CNP as a molecule regulating food intake and energy expenditure. Further analyses on precise mechanisms of CNP actions would lead to the better understanding of the significance of the CNP/guanylyl cyclase-B system in food intake and energy expenditure.

Modeling multisystem biological risk in young adults: The Coronary Artery Risk Development in Young Adults Study.

Although much prior research has focused on identifying the roles of major regulatory systems in health risks, the concept of allostatic load (AL) focuses on the importance of a more multisystems view of health risks. How best to operationalize allostatic load, however, remains the subject of some debate. We sought to test a hypothesized metafactor model of allostatic load composed of a number of biological system factors, and to investigate model invariance across sex and ethnicity. Biological data from 782 men and women, aged 32-47, from the Oakland, CA and Chicago, IL sites of the Coronary Artery Risk Development in Young Adults Study (CARDIA) were collected as part of the Year 15exam in 2000. These include measures of blood pressure, metabolic parameters (glucose, insulin, lipid profiles, and waist circumference), markers of inflammation (interleukin-6, C-reactive protein, and fibrinogen), heart rate variability, sympathetic nervous system activity (12-hr urinary norepinephrine and epinephrine) and hypothalamic-pituitary-adrenal axis activity (diurnal salivary free cortisol). A "metafactor" model of AL as an aggregate measure of six underlying latent biological subfactors was found to fit the data, with the metafactor structure capturing 84% of variance of all pairwise associations among biological subsystems. There was little evidence of model variance across sex and/or ethnicity. These analyses extend work operationalizing AL as a multisystems index of biological dysregulation, providing initial support for a model of AL as a metaconstruct of inter-relationships among multiple biological regulatory systems, that varies little across sex or ethnicity.

Cortisol levels during the menopausal transition and early postmenopause: observations from the Seattle Midlife Women's Health Study.

OBJECTIVE: Cortisol levels rise among some women during the late stage of the menopausal transition (MT), but we know little about changes in cortisol levels in relation to menopause-related factors (MT stage, urinary estrone glucuronide [E1G], testosterone, follicle-stimulating hormone [FSH]), stress-related factors (epinephrine, norepinephrine, and perceived stress), symptoms (hot flashes, mood, memory, and sleep), social factors (income adequacy, role burden, social support, employment, parenting, and history of sexual abuse), and health-related factors (depressed mood, perceived health, physical appraisal, body mass index, and smoking). The aim of the study was to examine the influence of menopause-related factors, stress-related factors, symptoms, social factors, and health-related factors on cortisol levels during the MT. METHODS: Participants were a subset of Seattle Midlife Women's Health Study who provided data during the late reproductive, early and late MT stages, or early postmenopause and who were not using hormone therapy or corticosteroids (N = 132 women, up to 5,218 observations). Data provided included menstrual calendars for staging the MT, annual health reports, health diaries, and overnight urine specimens (assayed for cortisol, catecholamines, E1G, and FSH) between 1990 and 2005 were included. Perceived stress, symptoms, and health behaviors were assessed in a health diary. Health-related and social factors were assessed in an annual health update. Multilevel modeling was used to test the effects of menopause-related and other factors on overnight cortisol levels. RESULTS: When tested with age as a measure of time, menopause-related covariates, including E1G, FSH, and testosterone, were associated with significant increases in overnight cortisol levels (P < 0.0001). Likewise, epinephrine and norepinephrine were each associated significantly with overnight cortisol levels (P < 0.0001). In multivariate analyses, E1G, FSH, and testosterone constituted the best set of predictors. CONCLUSIONS: Overnight cortisol levels during the MT were associated with E1G, testosterone, and FSH levels. In addition, they were significantly and positively associated with epinephrine and norepinephrine. MT stage, symptoms, and social, stress-related, and health-related factors had little relationship to overnight cortisol levels when other biological indicators were considered.

Socioeconomic status is related to urinary catecholamines in the Coronary Artery Risk Development in Young Adults (CARDIA) study.

OBJECTIVE: To determine whether socioeconomic status (SES) is associated with catecholamine levels (epinephrine [E] and norepinephrine [NE]-indicators of sympathetic nervous system [SNS] activity) in a community-based sample of men and women, Blacks and Whites, with a broad range of income; and to test whether such a relationship is mediated by psychosocial factors and/or health behaviors. METHODS: A total of 672 participants from the Coronary Artery Risk Development in Young Adults study (CARDIA) provided 12-hour, overnight urine samples, and completed sociodemographic, health behavior, and psychosocial questionnaires. RESULTS: Regardless of whether measured in terms of income, education, or occupation, higher SES was associated with lower urinary catecholamine levels, independent of age, race, and gender. These relationships were stronger in men than in women but were similar across Blacks and Whites. Smoking and greater levels of depressive symptoms accounted for some of the association of SES with E and, to a lesser extent, with NE. CONCLUSIONS: These data provide support for the hypothesis that lower SES is accompanied by increased physiologic distress, indicated by elevated SNS activity. Further, they suggest that the association of SES with catecholamines, like the associations of SES with morbidity and mortality, is apparent at all levels of the socioeconomic hierarchy.

Increased resting energy expenditure after 40 minutes of aerobic but not resistance exercise.

OBJECTIVE: Resting energy expenditure (REE) is increased 24 hours after high-intensity aerobic exercise lasting 60 minutes, whereas results have been inconsistent after resistance training and aerobic exercise of shorter duration. The objective of the study was to compare the effects of 40 minutes of high-intensity aerobic vs. resistance exercise on REE 19 to 67 hours after exercise. RESEARCH METHODS AND PROCEDURES: REE was compared 19, 43, and 67 hours after 40 minutes of aerobic training (AT; 80% maximum heart rate) or resistance training (RT; 10 repetitions at 80% maximum strength, two sets and eight exercises). Twenty-three black and 22 white women were randomly assigned to AT, RT, or no training (controls). Exercisers trained 25 weeks. REE was measured after a 12-hour fast. RESULTS: There was a significant time x group interaction for REE when adjusted for fat-free mass and fat mass, with post hoc tests revealing that the 50-kcal difference between 19 and 43 hours (1310 +/- 196 to 1260 +/- 161 kcal) and the 34-kcal difference between 19 and 67 hours (1310 +/- 196 to 1276 +/- 168 kcal) were significant for AT. No other differences were found, including RT (19 hours, 1256 +/- 160; 43 hours, 1251 +/- 160; 67 hours, 1268 +/- 188 kcal). Urine norepinephrine increased with training only in AT. After adjusting for fat-free mass, REE Delta between 19 and both 43 and 67 hours was significantly related to urine norepinephrine (r = 0.76, p < 0.01 and 0.68, p < 0.03, respectively). DISCUSSION: Consistent with findings on longer duration AT, these results show that 40 minutes of AT elevates REE for 19 hours in trained black and white women. This elevation did not occur with 40 minutes of RT. Results suggest that differences are, in part, due to increased sympathetic tone.

Assessment of continuous positive airway pressure treatment in obstructive sleep apnea syndrome using 24-hour urinary catecholamines.

BACKGROUND: Obstructive sleep apnea syndrome (OSAS) is related to diurnal sympathetic hyperactivity and increased blood pressure, both factors that are likely to lead to the development of cardiovascular disease. HYPOTHESIS: The study investigated whether 24-h urinary catecholamines would reflect the effect of obstructive sleep apnea on autonomic activity. METHODS: Standard polysomnography was performed in 17 patients with OSAS (age 53.7 +/- 13.5 years, mean +/- standard deviation). The number of apnea/hypopnea episodes per hour of sleep (apnea/hypopnea index [AHI]); number of oxygen desaturation episodes per hour (desaturation index [DSI]); arousals per hour (arousal index); lowest oxygen saturation (lowest SpO2); and percentages of stages 1, 2, 3/4, and rapid eye movement sleep (% stage 1, -2, and -3/4, and % REM, respectively) were measured. Overnight continuous positive airway pressure (CPAP) titration was performed the night after the baseline sleep measurements had been taken. Twenty-four-hour urinary adrenaline and noradrenaline were also examined. RESULTS: During the CPAP treatment, both 24-h urinary adrenaline and noradrenaline were significantly lower compared with natural sleep. Continuous positive airway pressure significantly decreased the AHI, DSI, % stage 1, and arousal index and significantly increased the lowest SpO2. There were no significant differences in % stage 2, % stage 3/4, and % REM between before and during CPAP treatment. Multiple analysis of covariance tests revealed that lowest SpO2 was the most important factor for increasing 24-h urinary noradrenaline levels (F = 4.75, p = 0.048). CONCLUSIONS: One night CPAP treatment could improve autonomic dysfunction. The assessment of 24-h urinary noradrenaline would provide important information for evaluating the effect of CPAP treatment.

Clinical assessment of norepinephrine transporter blockade through biochemical and pharmacological profiles.

BACKGROUND: To assess the sensitivity of biochemical, physiological, and pharmacological markers of peripheral norepinephrine (NE) transporter (NET) function, we chronically antagonized NET by a range of doses of duloxetine [(+)-N-methyl-3-(1-naphthalenyloxy)-2 thiophenepropanamine], which blocks the NE reuptake process. METHODS AND RESULTS: Duloxetine was administered in a randomized, placebo-controlled study in 15 healthy volunteers. Plasma from duloxetine-treated subjects (ex vivo effect) dose-dependently decreased radioligand binding to human NET (maximum inhibition was 60%) (P=0.02). The dose of intravenous tyramine required to raise systolic blood pressure by 30 mm Hg (PD30) increased dose-dependently with duloxetine and was significant at the end of the 120-mg/d dosage (P<0.001). The plasma dihydoxyphenylglycol to NE (DHPG/NE) ratio was reduced significantly at 2 weeks of treatment with 80 mg/d duloxetine (11.3 at baseline, 3.4 at 240 mg/d, P<0.001). Plasma NE was significantly increased starting at 120 mg/d duloxetine. Urine results (corrected for 24-hour creatinine excretion) showed a dose-dependent change from the baseline urinary excretion for NE, DHPG, and the DHPG/NE ratio. The most sensitive measure, the DHPG/NE ratio, was significant at the 80-mg dose. Urinary NE excretion was significantly raised after 2 weeks of treatment with 80 mg/d duloxetine (P<0.001), the lowest dose used in the study. CONCLUSIONS: These findings suggest that the degree of NET blockade can be assessed with the plasma or urine DHPG/NE ratio and the pressor effect of tyramine. Also, the DHPG/NE ratio is more sensitive at the lower end of NET inhibition, whereas tyramine exhibits a linear relation, with NET inhibition commencing at a higher dose.

Gender and ethnic differences in urinary stress hormones: the population-based Chicago Health, Aging, and Social Relations Study.

Gender and ethnic disparities in cardiovascular disease and mortality have spurred interest in the epidemiology of stress hormone production. Greater disease burden among men and blacks raises the possibility of gender and ethnic differences in stress hormone production. The purpose of this study was to determine whether urinary stress hormones were higher among men and blacks in a population-based sample. Urinary hormone analysis permits a time-integrated assessment of the stress response system. However, differences in collection and standardization strategies have led to inconsistent findings. Subjects were an ethnically diverse population-based sample of 229 men and women aged 50-67 yr who provided an overnight urine specimen. Urine concentration was standardized using a traditional creatinine-based approach as well as a new method that accounts for muscle mass. With the use of creatinine standardization, no gender or ethnic differences were noted in epinephrine or cortisol production. Norepinephrine levels were higher among women compared with men (P = 0.001), however. After accounting for muscle mass, we found that both epinephrine (P = 0.018) and norepinephrine (P = 0.033) levels were higher among men compared with women. No significant differences in cortisol production were found by gender or ethnicity. The consistency of these results with previous studies of 24-h urine samples suggests muscle mass should be accounted for when comparing overnight urinary hormone values across gender and ethnicity.

Urinary excretion of catecholamines, cortisol and their metabolites in Meishan and large white sows: validation as a non-invasive and integrative assessment of adrenocortical and sympathoadrenal axis activity.

Urinary free corticoids (cortisol and cortisone), catecholamines (norepinephrine or NE, epinephrine or E, dopamine or DA, and their O-methoxylated metabolites) as well as creatinine (Cr) were analysed in 42 spontaneously voided urine samples from Large White (LW, n = 20), Meishan (MS, n = 6), and LW x MS (F1, n = 16) lactating sows. The cortisol concentration in the urine of MS (28.1 pg/micrograms Cr) was five-fold greater than that of LW sows (6.2 pg/micrograms Cr, P < 10(-4)). F1 were intermediate (12.0 pg/micrograms Cr). Mean cortisone concentration was also larger in MS (13.5 pg/micrograms Cr) compared to LW (7.1 pg/micrograms Cr, P < 0.01). Although the differences were less pronounced, the concentrations of the catecholamines were also greater in MS than in LW sows (norepinephrine: 25.4 versus 5.9 pg/micrograms Cr, epinephrine: 8.7 versus 2.8 pg/micrograms Cr and dopamine: 59.2 versus 17.8 pg/micrograms Cr, P < 10(-4)). These results confirmed the hypercortisolism state of MS pigs previously shown by plasma cortisol assay and supported the hypothesis that the sympathetic nervous system is hyperactive in this breed. These urinary investigations may offer possible applications for the assessment of chronic stress.

Fluoxetine increases resting energy expenditure and basal body temperature in humans.

Humans lose weight when administered fluoxetine, an inhibitor of serotonin reuptake by nerve terminals. To determine whether increased energy expenditure contributes to this weight loss we admitted 20 nondepressed obese women to a metabolic unit where they were randomly assigned to 3 wk of a 1.76-MJ/d formula diet and either 60 mg fluoxetine/d or a placebo. Resting energy expenditure of the control subjects fell below normal after 5.6 +/- 0.6 d of energy restriction, whereas that of the fluoxetine-treated subjects increased by 4.4 +/- 1.8% (P < 0.005) within 3 d of commencing treatment. This increased resting energy expenditure then reversed and fell below normal after 9.8 +/- 0.9 d of energy restriction. Basal body temperature of the control subjects decreased insignificantly during the period of energy restriction, but that of the fluoxetine-treated subjects increased by 0.28 +/- 0.10 degrees C (P < 0.05) within 3 d of commencing diet and drug treatment. Urinary norepinephrine excretion and the serum triiodothyronine concentration decreased equally in both groups. Despite identical energy intakes and equal nitrogen balance, the fluoxetine-treated subjects lost weight faster than the control subjects during the final week of energy restriction (P < 0.05). We propose that serotonin reuptake inhibition increases energy expenditure by increasing basal body temperature.

The effects of a high carbohydrate diet on postprandial energy expenditure during exercise in rats.

Whether or not a high intake of carbohydrate increases postprandial energy expenditure during exercise was studied in rats. The rats were meal-fed regularly twice a day (0800-0900 hours and 1800-1900 hours) on either a high carbohydrate (CHO) (carbohydrate/fat/protein = 70/5/25, % of energy) or high fat (FAT) (35/40/25) diet for 12 days. On the final day of the experiment, all of the rats in each dietary group were fed an evening meal containing equal amounts of energy (420 kJ.kg-1 body mass). After the meal, they were divided into three subgroups: pre-exercise control (PC), exercise (EX), and resting control (RC). The PC-CHO and PC-FAT groups were sacrificed at 2030 hours. The EX-CHO and EX-FAT groups were given a period of 3-h swimming, and then sacrificed at 2330 hours. The RC-CHO and RC-FAT groups rested after the meal and were sacrificed at 2330 hours. Total energy expenditure during the period 1.5 h from the commencement of exercise was higher in EX-CHO than in EX-FAT. The respiratory exchange ratio was also higher in EX-CHO than in EX-FAT, suggesting enhanced carbohydrate oxidation in the former. Compared with both PC-FAT and RC-FAT, the liver glycogen content of EX-FAT rats was significantly decreased by exercise. On the other hand, the liver glycogen content of both EX-CHO and RC-CHO was higher than that of PC-CHO rats. The glycogen content of soleus muscle of EX-FAT was slightly decreased during exercise, however, that of EX-CHO increased significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Twenty-four-hour energy expenditure in pregnant and nonpregnant Gambian women, measured in a whole-body indirect calorimeter.

Twenty-four-hour energy expenditure (EE), daily and sleeping EE, and the energy cost of a standardized treadmill exercise were assessed in a respiration chamber in 41 young pregnant Gambian women at 12 (n = 11), 24 (n = 15), and 36 (n = 15) wk of gestation and compared with 13 nonpregnant nonlactating (NPNL) control women. The rate of 24-h EE was significantly higher (P less than 0.001) at 36 wk gestation (8443 +/- 243 kJ/d) than in the NPNL group (6971 +/- 172 kJ/d) or at 12 and 24 wk (7088 +/- 222 and 7188 +/- 192 kJ/d, respectively). Per unit body weight, no more differences in 24-h EE, daily and sleeping EE, or energy cost of walking were observed between pregnant and NPNL women. There was no statistical difference in the 24-h respiratory quotient among the groups. We conclude that the state of pregnancy in Gambian women induces a progressive rise in 24-h EE, which becomes significant in the third trimester and is proportional to body weight.

Ethnic differences in sympathetic nervous system-mediated energy expenditure.

The impact of sympathetic nervous system (SNS) activity on energy expenditure (EE) was evaluated in nondiabetic Caucasian and Pima Indian men while on a weight-maintenance diet using two approaches as follows. 1) The relationship between 24-h EE, measured in a respiratory chamber, and 24-h urinary norepinephrine was studied in 36 Caucasians [32 +/- 8 (SD) yr, 95 +/- 41 kg, 22 +/- 13% fat] and 33 Pimas (29 +/- 6 yr, 103 +/- 28 kg, 30 +/- 9% fat). There was no difference between the two groups in 24-h EE (2,422 vs. 2,523 kcal/24 h) and in urinary norepinephrine (28 vs. 31 micrograms/24 h), even after adjusting for body size and composition. Twenty-four-hour EE correlated significantly with 24-h urinary norepinephrine in Caucasians (r = 0.78, P less than 0.001) but not in Pimas (r = 0.03), independent of fat-free mass (FFM), fat mass, and age. 2) The effect of beta-adrenoceptor blockade with propranolol (120 micrograms/kg FFM bolus and 1.2 micrograms.kg FFM-1.min-1 for 45 min) on the resting metabolic rate (RMR) was evaluated in 36 Caucasians (30 +/- 6 yr, 103 +/- 36 kg, 25 +/- 11% fat) and 32 Pimas (28 +/- 6 yr, 100 +/- 34 kg, 27 +/- 10% fat). The RMR was similar in the two groups (2,052 vs. 1,973 kcal/24 h) even after adjustment for FFM, fat mass, and age and dropped significantly after propranolol infusion in Caucasians (-3.9%, P less than 0.001) but not in Pimas (-0.8%, P = 0.07).(ABSTRACT TRUNCATED AT 250 WORDS)

[Value of several hormone indicators and cyclic nucleotides in the assessment and prognosis of resistance to acute hypoxia during operator activities]. / Informativnost' nekotorykh gormonal'nykh pokazatelei i tsiklicheskikh nukleotidov v otsenke i prognoze ustoichivosti k vozdeistviiu ostroi gipoksii pri operatorskoi deiatel'nosti.

A study was performed in which 16 healthy volunteers, aged 25-40 years, worked in a two-dimensional tracking simulator and breathed a mixture containing 9-12% oxygen. This led to a higher incretion of cortisol, insulin, somatotropin, a greater renal excretion of epinephrine, norepinephrine, and a higher content of cAMP in lymphocytes, plasma and urine. The subjects with a higher insulin in plasma and renal excretion of catecholamines showed a longer time of tolerance to the above exposure which varied from 50 to 120 min. The high tolerance was combined with a greater activity of the sympathoadrenal system, incretion of cortisol and cAMP in lymphocytes. A significant correlation was demonstrated between cAMP in the above environments both before and after exposure.

Urinary catecholamines, plasma insulin and environmental factors in relation to body fat distribution.

The relationship of body fat distribution to insulin and the catecholamines, hormones that affect lipolysis differentially by fat site, was examined within an environmental context, including factors of medication use, physical activity, dietary intake, educational attainment, and age. Four cross-sectional body fat areas (cm2) were determined by three computed tomography (CT) scans (subcutaneous chest fat at the level of the nipples, subcutaneous and intra-abdominal fat at the level of the umbilicus, and subcutaneous left mid-thigh fat) in 191 second-generation Japanese-American men aged 45-74 years. The site-specific fat measurements were first examined in relation to use of beta-adrenergic antagonists, then to fasting plasma insulin and C-peptide levels and to urinary epinephrine and norepinephrine levels from a 24-h urine collection made during usual daily activities. Greater fat stores in the intra-abdominal area, even after adjustment for body mass index (BMI, weight/height2) and presence of coronary heart disease, were found to be related to use of beta-adrenergic antagonists. In men taking no adrenergic antagonists (n = 157), after adjustment for BMI, truncal fat measurements of the chest (partial r = -0.16, P less than 0.05) and intra-abdominal area (partial r = -0.21, P less than 0.05) were found to be inversely related to epinephrine, and intra-abdominal fat (partial r = 0.25, P less than 0.01) alone was directly related to fasting plasma insulin. With respect to other environmental variables, the significant inverse relationship of intra-abdominal fat (adjusted for BMI) with physical activity (partial r = -0.17, P less than 0.05) and the significant difference in intra-abdominal fat by educational attainment (college 102.3 +/- 5.7 vs no college 115.7 +/- 6.1 cm2, P = 0.03) became non-significant with adjustment, using multiple regression analysis, for insulin in the case of physical activity and epinephrine in the case of educational attainment. Thus, intra-abdominal fat showed a unique set of relationships to metabolic parameters which could be further related to certain environmental variables.

Assessment of cold induced alterations in catecholamine turnover of lean and glutamate-treated obese rats.

Excretion of norepinephrine (NE) and vanillylmandelic acid (VMA) in urine as well as NE-turnover in tissues from lean and glutamate-treated obese rats were determined in warm and cold environment. NE-and VMA-excretion in urine was elevated by cold exposure, indicating an activation of the sympathetic nervous system in animals of both groups. Organspecific NE-turnover responds with higher sensitivity to cold in obese rats but without complete compensation in brown adipose tissue. Urinary NE- and VMA- excretion as well as NE-turnover in organs confirmed that cold exposure activates the sympathetic nervous system. Measurement of NE-turnover in tissues gives organspecific information regarding alterations in sympathetic activity during cold exposure, whereas excretion of NE and VMA in urine is a summarizing measure for the whole body turnover only.