Care related pain in rehabilitation after orthopedic trauma: An exploratory study with qualitative data

OBJECTIVE

Care related pain (CRP) is generally under-estimated and rarely studied in rehabilitation as well as in general medecine. Beliefs about pain influence psychological distress, adjustment to pain and physical disability. In this sense, perceptions of CRP could limit recovery. This exploratory study aims to understand patients' and caregivers' subjective perceptions and beliefs about CRP.

PATIENTS AND METHODS

Questionnaires about CRP were submitted to members of the interdisciplinary team of a rehabilitation hospital and to patients with musculoskeletal complaints (cross-sectional design). Twenty patients were also individually interviewed (qualitative data). Four topics were addressed: frequency of CRP, situations and procedures causing CRP, beliefs about CRP and means used to deal with CRP.

RESULTS

Seventy-five caregivers and 50 patients replied to the questionnaire. CRP is a very common experience in rehabilitation and it is recognized by both groups. Generally, the situations causing CRP reflect the specificity of rehabilitation (mobilization…) and are similarly perceived by patients and caregivers, with patients considering them as more painful. Beliefs about CRP are clearly different from those usually associated with pain. Both groups point out the utilitarian and the inevitable character of CRP. They differ on that, that patients had a more positive view about CRP. They associate it more often with progress and see it as acceptable at least until a certain limit. They are also able to perceive the richness of means used by physiotherapists to help them coping with CRP.

CONCLUSION

Our data may suggest new keys to motivate patient to be active in rehabilitation for example in choosing carefully arguments or words which may fit theirs' beliefs about CRP, or in using various means to manage CRP. Promoting the use of relational competences with chronic pain patients and of a patient-centred approach may also be a concern in training caregivers.

Non Linear Weight Gain with Long Term Overfeeding in Man

This study deals with the pattern of body weight gain during an overfeeding period with a constant energy intake, in order to assess whether total daily energy expenditure (TEE) increased with body weight and thus could account for the progressive slow down in body weight gain over time. Twenty-four young adult males (12 pairs of identical twins) were overfed by 4.2 MJ per day, six days a week, for a total of 84 days during a 100-day overfeeding period. The total excess amount each man consumed was 353 MJ. It was assumed that, at a given time, the TEE increase (E) was dependent on body weight gain and energy cost (C) was proportional to the daily body weight gain. Results show an exponential increase in body weight, fat free mass, and fat mass (with half-times of 86, 57, and 84 days, respectively) that allows the calculation of E (246 +/- 37 kJ x kg(-1) x d(-1), mean +/- SE) and C (32.3 +/- 2.4 MJ x kg(-1)). Energy expenditure from other sources besides resting metabolic rate, such as physical activity and thermic effect of food, may represent as much as 65% of E. At the beginning of the overfeeding period, almost all the energy surplus was recovered as body substances but this proportion decreased to 60% after 100 days of overfeeding. It is concluded that 1) TEE changes were related to body weight change, 2) about 65% of E were accounted for by physical activity, thermic effect of food, or some other components, and 3) the fraction of the energy surplus stored as body substances decreased with the duration of overfeeding.

Relation BetweenBglIIPolymorphism in 3β-Hydroxysteroid Dehydrogenase Gene and Adipose Tissue Distribution in Humans

The aim of this study was to investigate the association between a restriction fragment length polymorphism (RFLP) at the 3beta-hydroxysteroid dehydrogenase locus and adipose tissue distribution phenotypes. A total of 132 unrelated individuals from the Quebec Family Study were followed prospectively for an average period of 11.3 years. The BglII polymorphism in exon 4 of the 3beta-HSD gene was detected by PCR. Body mass, body fat, and regional fat distribution indicators were adjusted for age and age2 within each gender. Associations were assessed in unrelated adults with ANOVA across three genotypes. No association was found for the indicators of body mass, body fat, and regional distribution of adipose tissue measured in 1992. In women, the changes (difference between data collected in 1992 and at entry) in the sum of six skinfolds (p=0.04), abdominal skinfold (p=0.01), and abdominal skinfold adjusted (p=0.03) for the sum of six skinfolds at entry were related to the BglII polymorphism at the 3beta-HSD locus. These relations were not found in men, but they gained less body mass and body fat over the 11.3-year period. This suggests that sequence variation at the 3beta-HSD locus or in neighboring genes on chromosome 1 may contribute to individual differences in body fat content and adipose tissue distribution in adult women, particularly in abdominal adipose tissue deposition as they grow older and gain body fat.

Foot varus in stroke patients: muscular activity of extensor digitorum longus during the swing phase of gait

BACKGROUND

Hemiparetic patients often present an abnormal leg muscles balance that can lead to foot deformities like equinovarus or varus.

OBJECTIVE

To assess whether a muscle imbalance between tibialis anterior and extensor digitorum longus was associated with a varus deformity of the foot during the swing phase of gait in stroke patients.

METHODS

Twenty hemiparetic patients presenting a foot varus during the swing phase of gait were compared to 16 healthy subjects. Gait was analyzed by video recording and by surface electromyography. Duration and magnitude of electromyographic signal were collected for tibialis anterior and extensor digitorum longus. Presence of an activity of the calf muscles during the swing phase was also evaluated.

RESULTS

Hemiparetic patients exhibited more often premature activity of the calf muscles (p<0.05) and greater duration and amplitude asymmetry between tibialis anterior and extensor digitorum longus (p<0.05). These asymmetries were explained by a decrease in extensor digitorum longus activity (p<0.05).

CONCLUSIONS

The activity of extensor digitorum longus muscle during the swing phase of gait is important to balance the foot in the frontal plane. The activation of that muscle should be included in rehabilitation programs.

Skeletal muscle low attenuation area and maximal fat oxidation rate during submaximal exercise in male obese individuals

BACKGROUND

Muscle triacylglycerols (TG) are known to be a source of energy during submaximal exercise.

OBJECTIVE

The aim of this study was to assess whether an index of muscle fat content is related to maximal fat oxidation rate (FATOXmax) in 58 obese men (mean age 46.0+/-0.8 (s.e.) y, body weight 96.4+/-1.4 kg, percentage fat: 31.9+/-0.5%) [corrected].

DESIGN

FATOXmax was defined as the highest value of fat oxidation rate, measured by indirect calorimetry, while walking on a treadmill (4.3 km/h) at three different slopes: 0% (40+/-1% of VO2max), 3% (47+/-1% of VO2max) and 6% (58+/-1% of VO2max). Fat-free mass (FFM) and fat mass (FM) were measured with the underwater technique and scans were obtained by computed tomography (CT) at the mid thigh level to assess areas of adipose tissue within skeletal muscle, ie deep adipose tissue (DAT), subcutaneous adipose tissue (SAT), skeletal muscle (M) and low attenuation skeletal muscle (LAM, range of attenuation values: 0-34 Hounsfield units). LAM and DAT were used as indices of skeletal muscle fat content.

RESULTS

FATOXmax, adjusted for age, was correlated with FFM (r=0.26, P<0.05), LAM (r=0.29, P<0.05), abdominal visceral adipose tissue (r=0.30, P<0.05) and plasma free fatty acid (FFA) levels (r=0.33, P<0.05) but not with SAT (r=0.03) and DAT (r=0.21) [corrected]. In a stepwise linear multiple regression, plasma FFA, age and LAM significantly predicted FATOXmax (r2=0.27). Each independent variable explained about 9% of the FATOXmax variance.

CONCLUSION

LAM makes a significant but weak contribution to the modulation of fat oxidation during submaximal exercise in obese men.

In vivo whole-body resting energy expenditure and insulin action in human malignant hyperthermia

BACKGROUND

Malignant hyperthermia (MH) is a pharmacogenetic disease triggered by volatile anesthetics or succinylcholine. The disorder is heterogenetic and caused by abnormal calcium regulation within skeletal muscle cells. No clear metabolic differences have been found in MH-susceptible (MHS) persons in vivo while not having MH episodes, but some reported signs suggest that insulin action and energy turnover might be altered in muscle of MHS persons.

METHODS

In fasting and insulin-stimulated conditions, using the glucose clamp technique and indirect calorimetry, we assessed in vivo resting energy expenditure (REE) and nutrient utilization rates in 10 MHS, 5 MH-equivocal (MHE) and 10 MH-negative (MHN) persons from 14 families. With a model using the persons' fat-free mass, fat mass, age, and gender, we calculated their predicted REE and compared it with measured REE in 10 MHS and 10 MHN persons (measured - predicted = residual REE).

RESULTS

In vivo measured REE and glucose disposal rates were similar in 10 MHS and 10 MHN persons. Only during insulin stimulation was residual REE greater in MHS persons (6.4%; P = 0. 013).

CONCLUSIONS

In vivo insulin action is unimpaired in MHS persons. Although the absolute values of whole-body REE are the same in MHS and MHN persons, the part of REE independent of the determinants fat-free mass, fat mass, age, and gender is moderately greater in MHS than in MHN persons during insulin exposure. This suggests that MH susceptibility might influence insulin-stimulated energy turnover in muscle.

Linkage and association of the sodium potassium-adenosine triphosphatase alpha2 and beta1 genes with respiratory quotient and resting metabolic rate in the Québec Family Study

The purpose of this study was to examine the relationship between the alpha2 (exon 1 and exon 21-22 with BglII) and beta1 (MspI and PvuII) genes of the sodium potassium adenosine triphosphatase and resting metabolic rate (RMR) and respiratory quotient (RQ). The sample included 582 participants from 171 families of the Québec Family Study. RMR and RQ were adjusted for age, sex, fat mass, and fat free mass. Sib-pair analyses indicated a significant linkage between RQ and the alpha2 exon 1 marker (P = 0.03) and the alpha2 exon 21-22 marker (P = 0.02). No linkage was detected between the beta1 markers and either RMR or RQ, whereas RMR was not linked with the alpha2 makers. There was a significant interaction (P < 0.0003) between alpha2 exon 1 carrier status and age group [younger (< 45 yr) vs. older (> or = 45 yr) adults] for RQ. The association between carrier status and RQ was significant in younger adults (RQ = 0.76 in carriers vs. 0.80 in noncarriers, P < 0.0001) but was not in older adults (RQ = 0.81 in carriers vs. 0.80 in noncarriers). The alpha2 exon 1 gene accounted for approximately 9.1% and 0.3% of the variance in RQ in younger and older adults, respectively. The results suggest that the sodium potassium adenosine triphosphatase alpha2 gene may play a role in fuel oxidation, particularly in younger individuals.

Linkage of the Na,K-ATPase alpha 2 and beta 1 genes with resting and exercise heart rate and blood pressure: cross-sectional and longitudinal observations from the Quebec Family Study

OBJECTIVE

To investigate whether genetic variations in the genes encoding the alpha and beta subunits of the Na,K-ATPase are linked with hemodynamic phenotypes.

DESIGN AND PARTICIPANTS

Cross-sectional data based on 533 subjects (no antihypertensive medication) were obtained from 150 families of phase 2 of the Quebec Family Study, together with longitudinal data from 338 subjects (105 families) who had been measured 12 years earlier in phase 1 of the Quebec Family Study.

MAIN OUTCOME MEASURES

Restriction fragment length polymorphisms were examined at the alpha 2 (exon 1 and exon 21-22 with BglII) and beta 1 (Msp I and Pvu II) loci of Na,K-ATPase. Hemodynamic phenotypes measured included systolic and diastolic blood pressure, heart rate and rate-pressure product at rest and during low-intensity exercise.

RESULTS

Sib-pair analysis revealed relatively strong linkages (P = 0.0003-0.002) between the resting heart rate and rate-pressure product and the alpha 2 exon 21-22 marker and alpha 2 haplotype. Moreover, the alpha 2 exon 21-22 marker showed suggestive linkages (P = 0.01 to 0.043) with resting systolic blood pressure and exercise diastolic blood pressure, heart rate and rate-pressure product, and the alpha 2 haplotype with exercise diastolic blood pressure and rate-pressure product and the 12-year change in resting systolic blood pressure (P = 0.03 to 0.05). Both the beta 1 Msp I marker and the beta 1 haplotype were linked with the resting rate-pressure product (P = 0.007 and 0.003, respectively), and all beta 1 markers showed linkage with the change in resting systolic blood pressure (P = 0.00005 to 0.024). In men, there was a significant (P = 0.01) interaction between the alpha 2 exon 21-22 genotype and the postglucose plasma insulin level with regard to resting systolic blood pressure.

CONCLUSIONS

These data suggest that the alpha 2 and beta 1 genes of Na,K-ATPase contribute to the regulation of hemodynamic phenotypes in healthy subjects.

A major gene for resting metabolic rate unassociated with body composition: results from the Québec Family Study

A major gene hypothesis for resting metabolic rate (RMR) was investigated using segregation analysis (POINTER) of data on families participating in Phase 2 of the Québec Family Study. Complete analyses were conducted on RMR adjusted for age, and also on RMR adjusted for age and other covariates, primarily fat mass (FM) and fat-free mass (FFM). Prior to adjustment for covariates, support for a major gene hypothesis was equivocal-i.e., there was evidence for either a major gene or a multifactorial component (i.e., polygenic and/or familial environment). The multifactorial model was preferred over the major gene model, although the latter did segregate according to Mendelian expectations. However, after the effects of FM and FFM were accounted for, a major gene effect was unambiguous and compelling. The putative locus accounted for 57% of the variance, affected 7% of the sample, and led to high values of RMR. The lack of a significant multifactorial effect suggested that the familial etiology of RMR adjusted for FM and FFM was likely to be entirely a function of the major locus. Comparing the RMR results from pre- and post-adjustment for FM and FFM suggests a plausible hypothesis. We know from earlier studies in this sample that there is a putative major gene for FM and a major non-Mendelian effect for FFM. The current study leads us to speculate that: (1) the gene(s) affecting body size and body composition also may have an effect on RMR, and further (2) removal of the effect of the major gene(s) for body size and composition allowed for detection of an additional major gene affecting only the RMR. Thus, RMR appears to be an oligogenic trait.

Genetic pleiotropy for resting metabolic rate with fat-free mass and fat mass: the Québec Family Study

Shared genetic and familial environmental causes for the associations among resting metabolic rate (RMR), fat-free mass (FFM), and fat mass (FM) were investigated in families participating in phase 2 of the Québec Family Study. A multivariate familial correlation model assessing the pattern of significant cross-trait correlations between family members (e.g., RMR in parents with FFM in offspring) was used to infer the etiology of the associations. For each of FM and FFM with RMR, significant sibling, parent-offspring, and intraindividual cross-trait correlations suggests the associations are familial. Furthermore, the lack of significant spouse cross-trait correlations suggests that the familial aggregation is primarily genetic. Bivariate heritability estimates suggest that as much as 45% to 50% of the shared variance between FFM and RMR may be genetic, and as much as 28% to 34% for FM and RMR. This study supports the notion that the gene(s) affecting each of FFM and FM also influence the RMR. Moreover, the lack of any familial associations between FFM and FM suggests that the effects of each body size component on RMR are independent, i.e., more than one genetic source on the RMR-body size association. The possibility that RMR is an oligogenic trait (i.e., more than one underlying genetic etiology) should be further investigated using more complex multivariate segregation methods until specific genes can be tested.

Inhibition of Na(+)-K(+)-ATPase by digoxin and its relation with energy expenditure and nutrient oxidation rate

This study investigates the effects of digoxin, an inhibitor of the Na+ pump (Na(+)-K(+)-ATPase), on resting metabolic rate (RMR), respiratory quotient (RQ), and nutrient oxidation rate. Twelve healthy male subjects followed a double-blind protocol design and received either 1 mg/day digoxin or a placebo 2 days before indirect calorimetry measurements. Digoxin induced a 0.22 +/- 0.07 kJ/min or 3.8 +/- 1.5% (mean +/- SE, P = 0.01) decrease in RMR and a 0.40 +/- 0.13 kJ/min (P = 0.01) decrease in fat oxidation rate, whereas carbohydrate and protein oxidation rates did not change significantly. A dose-response relationship between serum digoxin and RQ was observed. These results suggest that digoxin reduces not only RMR but also fat oxidation rate by mechanisms that remain to be elucidated. Because a linkage and an association between genes coding the Na(+)-K(+)-ATPase and the RQ have been previously observed, the present demonstration of an effect of Na(+)-K(+)-ATPase inhibition on fat oxidation rate strengthens the concept that the activity of this enzyme may play a role in body weight regulation.

Plasma glucose, insulin, and glucagon before and after long-term overfeeding in identical twins

Plasma glucose, insulin, and glucagon levels were measured before and after long-term overfeeding (4.2 MJ/d during a 100-day period) in 24 lean adults (12 pairs of monozygotic twins). Fasting plasma glucose, insulin, and glucagon were significantly increased by overfeeding. During a 75-g oral glucose tolerance test (OGTT), no major alteration in glucose tolerance was observed and insulin area under the curve was increased. During a meal test, insulin and glucagon areas under the curve were increased. The pre-overfeeding values for glucose, insulin, and glucagon (fasting and areas) were not correlated with the gains in body weight and in fat mass. However, fasting glucagon before overfeeding was positively correlated with the gains in abdominal visceral fat and in femoral fat. The changes with overfeeding in insulin area during the OGTT were positively correlated with the changes in total subcutaneous fat, even after adjustment for total body fat gain. Significant twin intrapair similarity was observed for fasting plasma glucagon before overfeeding and for the changes in fasting insulin and glucagon with overfeeding. These results indicate that (1) in response to long-term overfeeding, both fasting insulin and glucagon are increased; (2) initial levels of glucose, insulin, and glucagon do not predict the gains in body weight and total body fat during overfeeding, but are related to changes in indicators of fat topography; (3) the changes in total subcutaneous fat represent an important correlate of insulin changes with overfeeding; and (4) the genotype could be an important determinant of insulin and glucagon responses to a prolonged positive-energy-balance period.

DNA variation in the genes of the Na,K-adenosine triphosphatase and its relation with resting metabolic rate, respiratory quotient, and body fat

The aim of this study was to investigate in 261 subjects from 58 families the association between DNA variation at the genes coding for the Na,K-ATPase peptides and resting metabolic rate (RMR), respiratory quotient (RQ), and percent body fat (%FAT). Five restriction fragment length polymorphisms (RFLP) at three Na,K-ATPase genes were determined: one at the alpha 1 locus (BglII), and two at the beta locus (beta MspI and beta PvuII). Haplotypes were determined from the two variable sites of the alpha 2 gene (alpha 2 haplotypes) and the beta gene (beta haplotypes). There was a strong trend for %FAT to be related to the RFLP generated by BglII at the alpha 2 exons 21-22 in males (P = 0.06) and females (P = 0.05). RQ was (a) associated with the BglII RFLP at the alpha 2 exon 1 (P = 0.02) and with the alpha 2 8.0 kb/4.3 kb haplotype (P = 0.04) and (b) linked with the beta gene MspI marker (P = 0.04) and with the beta 5.3 kb/5.1 kb haplotype (P = 0.008) based on sib-pair analysis. The present study suggests that the genes encoding Na,K-ATPase may be associated or linked with RQ and perhaps with %FAT but not with RMR.

Detection of a MspI restriction fragment length polymorphism for the human sex hormone-binding globulin (SHBG) gene

A rare polymorphism in the human sex hormone-binding globulin (SHBG) gene was detected using a human SHBG cDNA probe. It is the first DNA sequence variation reported in this gene.

Genetic influences on energy expenditure in humans

Variations in human energy expenditure are partly because of an influence of the genotype, even after control for the well-established concomitants of energy expenditure. Using the techniques of genetic epidemiology, we have found that about 40% of the variance in resting metabolic rate, thermic effect of food, and energy cost of low-to-moderate intensity exercise (< or = 5 times the resting metabolic rate) is explained by inherited characteristics. A significant genetic effect has also been reported for the level of habitual physical activity. The existence of a genotype-environment interaction has also been investigated. Thus, in response to chronic overfeeding, as well as negative energy balance, changes in the components of energy expenditure exhibit significant identical twin pair resemblance. Nutrient partitioning is emerging as a major determinant of the individual differences in metabolic rate responses to overfeeding or negative energy balance conditions. Taken as a whole, these observations consistently support the hypothesis that heredity plays a significant role in the various components of energy expenditure in humans.

Effect of dexfenfluramine on energy expenditure in man

A short review has been made of the experimental studies performed in man, in which the effect of dexfenfluramine (D-F) on resting energy expenditure has been explored. It appears that the extent to which D-F possesses thermogenic properties (in addition to its anorectic effect) still remains controversial. Some investigators found either no significant increase in energy expenditure in response to the drug or a moderate effect in post-absorptive and/or postprandial state. It may be reasonable to assume that the supplementary weight loss observed with D-F as compared to a placebo can be primarily attributed to its anorectic effect rather than to its putative thermogenic effect.

Lean-body-mass composition and resting energy expenditure before and after long-term overfeeding

This report deals with the association between the constituents of lean body mass (LBM) and resting metabolic rate (RMR) before and after a 100-d overfeeding period. Computed-tomography (CT) scan of 22 young adult males at nine different body levels were used to estimate adipose tissue mass (ATMCT), LBMCT, skeletal-muscle mass (SMMCT), and non-muscular LBMCT (NM-LBMCT). Before overfeeding, all body constituents, except ATMCT, were significantly correlated with RMR. Only body mass changes were significantly correlated with RMR changes. Comparison of these results with those of several studies in the literature reveals that the relationship between RMR and fat-free mass is highly influenced by the size of the SD for the latter variable. In stepwise-multiple-regression analysis, only SMMCT could be used to predict RMR. It was concluded that SMMCT and ATMCT, but not NM-LBMCT, increased during overfeeding and that the best correlates of RMR remain LBMCT, SMMCT, and body mass.

Human resting energy expenditure in relation to dietary potassium

This study investigates the putative effect of potassium on energy expenditure. Eight young adult men were submitted to two different normocaloric mixed diets in a randomized order, containing either 163 +/- 9 or 69 +/- 2 mmol potassium/d. On the fifth day of each diet, after an overnight fast, resting metabolic rate (RMR) was measured over a 1-h period. After these measurements, either a potassium load (50 mmol) or a placebo were given to subjects submitted to the low- or the high-potassium diet, respectively. RMR was then measured again for 3 h and the last hour was kept for further analysis. Results showed that acute and chronic variations in potassium intake do not induce significant changes in RMR, and chronic but not acute changes in serum potassium concentration were significantly correlated with changes in energy expenditure (r = 0.74, P less than 0.05) by mechanisms that remain to be elucidated.

Aerobic performance at altitude: effects of acclimatization and hematocrit with reference to training

The aim of the present investigation carried out on six members of the Swiss 1981 Mt. Lhotse Shar (8398 m) expedition was to assess the quantitative role of some of the determinants of VO2max at altitude. The loss of VO2max expected for the investigated altitude range was partially counterbalanced by the training undergone by the subjects during the approach to the base camp. delta VO2max was -18% instead of the expected 30%-35%. The VO2max value attained shortly after arrival at 5200 m was not significantly increased (38.4 +/- 4.4 SD vs 36.9 +/- 3.3 ml O2.kg-1.min-1) with a progressive rise of Hb from 16.4 +/- 0.8 to 18.2 +/- 1 g/100 ml of blood. Hemodilution, by oral administration of 2 liters of the isosmolar solution ISOSTAR, at 5200 m led to a 2.3% decrease of Hct and a 7.3% reduction of VO2max per kg of body weight. The product of heart rate times systolic arterial pressure ("double product") was somewhat (but not significantly) greater in hypoxia than in normoxia at all work loads. The maximum value for this product, however, was 10%-15% lower at 5200 than at 400 m. The increase of Hb from 15.1 +/- 0.7 to 17.1 +/- 1.6 g/100 ml of blood pre- to post-expedition was not accompanied by a significant increase of VO2max determined at 400 m either absolute or per kg of body weight.

The parasympathetic nervous system and the thermic effect of glucose/insulin infusions in humans

The thermic effect of glucose/insulin infusions was investigated in seven healthy young men before and during either inhibition (atropine sulphate 10 micrograms/kg bolus; 10 micrograms/kg/h) or stimulation (edrophonium chloride, 10 mg bolus; 0.75 mg/min starting rate) of the parasympathetic nervous system. The thermic effects of glucose/insulin were 6.2% +/- 0.4% and 5.6% +/- 0.7% before atropine and edrophonium, respectively, and increased to 7.1% +/- 0.5% (NS) with atropine and 7.5% +/- 1.2% (P less than .05) with edrophonium. In four subjects atropine or edrophonium was infused before the hyperinsulinemic, euglycemic clamp. A significant increase in resting metabolic rate and plasma norepinephrine concentrations was observed with edrophonium alone. When the thermic effects of glucose/insulin were calculated with respect to the metabolic rates observed during the drug infusions alone, they were 5.9% +/- 1.4% and 3.6% +/- 0.6% (NS) for the clamp + atropine and clamp + edrophonium, respectively. These results demonstrate that the increases in the thermic effect of glucose/insulin infusions observed during inhibition or stimulation of the parasympathetic nervous system were due to atropine or edrophonium increasing the resting metabolic rate rather than increasing the thermic response to glucose-insulin infusions. However, because it has been shown that atropine can decrease the thermic effect of an orally administered meal by approximately 60%, it would appear that the parasympathetic nervous system can influence the thermic effect of food by affecting the rate of digestion, absorption and storage of the ingested nutrients.

After effects of chronic hypoxia on cardiac output and muscle blood flow at rest and exercise

Cardiac output (Q, by N2-CO2 rebreathing) and limb muscle blood flow (qm, from 133Xe clearance) were determined in eight male subjects at rest and during cycloergometric loads immediately before and 12 days after return from the 1981 Swiss Lhotse Shar (8,398 m) Expedition. Compared to control conditions, after exposure to hypoxia: 1) Q was unchanged at rest and at 75 watts (W) but was 18% less (P less than 0.01) at 150 W with constant heart rate (approximately 140 beats X min-1); 2) qm in the vastus lateralis was identical at rest but 26% and 39% less (P less than 0.05 and P less than 0.001, respectively) at two submaximal leg work loads (75 and 125 W); 3) qm in the biceps at 50 W was 34% less (P less than 0.01); 4) hemoglobin flow (QHb and qmHb), similarly to blood flow (Q and qm), was significantly reduced; 5) the qm adjustment rate, measured from the time required to attain a new steady state upon a square wave change of work load starting from rest, was slower, particularly at the lower work loads. From the above results as well as from corresponding morphometric findings showing in the same subjects: 1) a decrease of the ratio between fiber section and number of capillaries and 2) a rise of the mitochondrial to fiber volume ratio, it is concluded that during altitude acclimatization peripheral O2 delivery becomes more efficient.

Cardiac output distribution during vasopressin infusion or dehydration in conscious dogs

To better understand the role of arginine vasopressin in cardiovascular regulation, we measured in unanesthetized dogs regional blood flows with radioactive microspheres before and during 1-h vasopressin infusions that increased the vasopressin concentration of plasma by 11 +/- 0.6 pg/ml. Cardiac output measured by an electromagnetic flowmeter decreased by 13%. Blood flows to the skeletal muscle and skin, the areas most affected, decreased by 30.8 and 34.3%, respectively. In the same group of dogs a period of 48-h water restriction increased plasma vasopressin by 6.9 +/- 1.3 pg/ml and reduced cardiac output by 14.4%. Skeletal muscle blood flow decreased by 32.8%, a pattern strikingly similar to that following vasopressin infusion. Obvious differences between vasopressin infusion and dehydration were also noted, in particular in the skin and splanchnic areas. However, the possibility that vasopressin contributed to the cardiovascular adjustments to dehydration must be considered. The use of an antagonist of the vascular effects of vasopressin, [1-deaminopenicillamine, 2-(O-methyl)tyrosine]arginine-vasopressin ([dPTyr(Me)]AVP), did not permit us to clarify this issue, because this analogue given alone exerted pronounced systemic and regional cardiovascular effects that resembled those of vasopressin.

Cardiovascular effects of vasopressin infused into the vertebral circulation of conscious dogs

1. Seven conscious dogs received arginine-vasopressin infusions (100 and 1000 fmol min--1 kg--1) through catheters implanted in the left vertebral artery or the inferior vena cava while arterial pressure, cardiac output (electromagnetic flowmeter) and heart rate were measured. 2. Despite similar increases in plasma vasopressin concentrations, intravertebral administration induced a lesser increase in mean arterial pressure and a greater decrease in heart rate than the same infusion given intravenously. 3. These results suggest that vasopressin has an effect on structures of the central nervous system involved in cardiovascular control, possibly by affecting the baroreceptor reflex.