Sympathetic single axonal discharge after spinal cord injury in humans: activity at rest and after bladder stimulation.

STUDY DESIGN: Clinical experimental mechanistic study. OBJECTIVES: (1) To determine in three spinal cord-injured patients whether individual muscle sympathetic nerve fibres below the level of the spinal lesion display spontaneous activity. (2) To determine in these patients if individual sympathetic vasoconstrictor fibres show a prolonged discharge following a bladder stimulus. SETTING: University hospital in Gothenburg, Sweden. METHODS: Microneurographic recordings of action potentials from individual muscle nerve sympathetic fibres in a peroneal nerve. Recordings of skin blood flow and electrodermal responses in a foot. RESULTS: In all patients, there was sparse ongoing spontaneous impulse traffic in individual sympathetic fibres. Brisk mechanical pressure over the urinary bladder evoked a varying number of action potentials in individual fibres, but the activity was brief and did not continue after the end of the evoked multiunit burst. CONCLUSION: Prolonged discharges in individual sympathetic fibres are unlikely to contribute to a long duration of blood pressure increases induced by brief bladder stimuli.

Preschool children born moderately preterm have increased waist circumference at two years of age despite low body mass index.

AIM: To investigate the development of waist circumference (WC) in preschool children born preterm compared with a population-based reference. BACKGROUND: Children born preterm are reported to be insulin resistant, despite being lean during early childhood. We hypothesize that the mechanism is through increased visceral adiposity. METHODS: Data from 4446 preschool children (2169 girls/2277 boys) born in 2001-2006 from a population-based study were compared with longitudinal measurements of body mass index (BMI) and WC from a cohort of 152 children (64 girls/88 boys) born moderately preterm in 2002-2004 (gestational age, 32-37 weeks). RESULTS: In the preterm children, the mean WC was 2.8 cm larger compared with the reference group (p < 0.001) at 2 years of age but not at 5 years of age. There was no significant difference in the mean BMI at 2 years of age. The preterm group was significantly leaner at 5 years of age, with a mean BMI of 15.13 compared with 15.98 in the reference group (p < 0.001). CONCLUSION: Children born moderately preterm present as lean during early childhood but have an increased waist circumference in infancy, pointing towards a change in fat distribution with more abdominal fat. This may have implications for their metabolic status.

International spinal cord injury skin and thermoregulation function basic data set.

OBJECTIVES: To create an international spinal cord injury (SCI) skin and thermoregulation basic data set within the framework of the International SCI Data Sets. SETTING: An international working group. METHODS: The draft of the data set was developed by a working group comprising members appointed by the American Spinal Injury Association (ASIA), the International Spinal Cord Society (ISCoS) and a representative of the Executive Committee of the International SCI Standards and Data Sets. The final version of the data set was developed after review and comments by members of the Executive Committee of the International SCI Standards and Data Sets, the ISCoS Scientific Committee, ASIA Board, relevant and interested international organizations and societies, individual persons with specific interest and the ISCoS Council. To make the data set uniform, each variable and each response category within each variable have been specifically defined to promote the collection and reporting of comparable minimal data. RESULTS: Variables included in the present data set are: date of data collection, thermoregulation history after SCI, including hyperthermia or hypothermia (noninfectious or infectious), as well as the history of hyperhidrosis or hypohidrosis above or below level of lesion. Body temperature and the time of measurement are included. Details regarding the presence of any pressure ulcer and stage, location and size of the ulcer(s), date of appearance of the ulcer(s) and whether surgical treatment has been performed are included. The history of any pressure ulcer during the last 12 months is also noted.

International spinal cord injury pulmonary function basic data set.

OBJECTIVES: To develop the International Spinal Cord Injury (SCI) Pulmonary Function Basic Data Set within the framework of the International SCI Data Sets in order to facilitate consistent collection and reporting of basic bronchopulmonary findings in the SCI population. SETTING: International. METHODS: The SCI Pulmonary Function Data Set was developed by an international working group. The initial data set document was revised on the basis of suggestions from members of the Executive Committee of the International SCI Standards and Data Sets, the International Spinal Cord Society (ISCoS) Executive and Scientific Committees, American Spinal Injury Association (ASIA) Board, other interested organizations and societies and individual reviewers. In addition, the data set was posted for 2 months on ISCoS and ASIA websites for comments. RESULTS: The final International SCI Pulmonary Function Data Set contains questions on the pulmonary conditions diagnosed before spinal cord lesion,if available, to be obtained only once; smoking history; pulmonary complications and conditions after the spinal cord lesion, which may be collected at any time. These data include information on pneumonia, asthma, chronic obstructive pulmonary disease and sleep apnea. Current utilization of ventilator assistance including mechanical ventilation, diaphragmatic pacing, phrenic nerve stimulation and Bi-level positive airway pressure can be reported, as well as results from pulmonary function testing includes: forced vital capacity, forced expiratory volume in one second and peak expiratory flow. The complete instructions for data collection and the data sheet itself are freely available on the website of ISCoS (http://www.iscos.org.uk).

Low risk HLA-DQ and increased body mass index in newly diagnosed type 1 diabetes children in the Better Diabetes Diagnosis study in Sweden.

OBJECTIVE: Type 1 diabetes and obesity has increased in childhood. We therefore tested the hypothesis that type 1 diabetes human leukocyte antigen DQ (HLA-DQ) risk genotypes may be associated with increased body mass index (BMI). DESIGN: The type 1 diabetes high-risk HLA-DQ A1*05:01-B1*02:01/A1*03:01-B1*03:02 genotype along with lower risk DQ genotypes were determined at the time of clinical onset by PCR and hybridization with allele-specific probes. BMI was determined after diabetes was stabilized. SUBJECTS: A total of 2403 incident type 1 diabetes children below 18 years of age were ascertained in the Swedish national Better Diabetes Diagnosis (BDD) study between May 2005 to September 2009. All children classified with type 1 diabetes, including positivity for at least one islet autoantibody, were investigated. RESULTS: Overall, type 1 diabetes HLA-DQ risk was negatively associated with BMI (P<0.0008). The proportion of the highest risk A1*05:01-B1*02:01/A1*03:01-B1)03:02 genotype decreased with increasing BMI (P<0.0004). However, lower risk type 1 diabetes DQ genotypes were associated with an increased proportion of patients who were overweight or obese (P<0.0001). Indeed, the proportion of patients with the low-risk A1*05:01-B1*02:01/A1*05:01-B1*02:01 genotype increased with increasing BMI (P<0.003). The magnitude of association on the multiplicative scale between the A1*05:01-B1*02:01/A1*05:01-B1*02:01 genotype and increased BMI was significant (P<0.006). The odds ratio in patients with this genotype of being obese was 1.80 (95% confidence interval 1.21-2.61; P<0.006). The increased proportion of overweight type 1 diabetes children with the A1*05:01-B1*02:01 haplotype was most pronounced in children diagnosed between 5 and 9 years of age. CONCLUSIONS: Susceptibility for childhood type 1 diabetes was unexpectedly found to be associated with the A1*05:01-B1*02:01/A1*05:01-B1*02:01 genotype and an increased BMI. These results support the hypothesis that overweight may contribute to the risk of type 1 diabetes in children positive for HLA-DQ A1*05:01-B1*02:01.

International spinal cord injury cardiovascular function basic data set.

OBJECTIVE: To create an International Spinal Cord Injury (SCI) Cardiovascular Function Basic Data Set within the framework of the International SCI Data Sets. SETTING: An international working group. METHODS: The draft of the data set was developed by a working group comprising members appointed by the American Spinal Injury Association (ASIA), the International Spinal Cord Society (ISCoS) and a representative of the executive committee of the International SCI Standards and Data Sets. The final version of the data set was developed after review by members of the executive committee of the International SCI Standards and Data Sets, the ISCoS scientific committee, ASIA board, relevant and interested international organizations and societies, individual persons with specific interest and the ISCoS Council. To make the data set uniform, each variable and each response category within each variable have been specifically defined in a way that is designed to promote the collection and reporting of comparable minimal data. RESULTS: The variables included in the International SCI Cardiovascular Function Basic Data Set include the following items: date of data collection, cardiovascular history before the spinal cord lesion, events related to cardiovascular function after the spinal cord lesion, cardiovascular function after the spinal cord lesion, medications affecting cardiovascular function on the day of examination; and objective measures of cardiovascular functions, including time of examination, position of examination, pulse and blood pressure. The complete instructions for data collection and the data sheet itself are freely available on the websites of both ISCoS (http://www.iscos.org.uk) and ASIA (http://www.asia-spinalinjury.org).

International standards to document remaining autonomic function after spinal cord injury.

STUDY DESIGN: Experts opinions consensus. OBJECTIVE: To develop a common strategy to document remaining autonomic neurologic function following spinal cord injury (SCI). BACKGROUND AND RATIONALE: The impact of a specific SCI on a person's neurologic function is generally described through use of the International Standards for the Neurological Classification of SCI. These standards document the remaining motor and sensory function that a person may have; however, they do not provide information about the status of a person's autonomic function. METHODS: Based on this deficiency, the American Spinal Injury Association (ASIA) and the International Spinal Cord Society (ISCoS) commissioned a group of international experts to develop a common strategy to document the remaining autonomic neurologic function. RESULTS: Four subgroups were commissioned: bladder, bowel, sexual function and general autonomic function. On-line communication was followed by numerous face to face meetings. The information was then presented in a summary format at a course on Measurement in Spinal Cord Injury, held on June 24, 2006. Subsequent to this it was revised online by the committee members, posted on the websites of both ASIA and ISCoS for comment and re-revised through webcasts. Topics include an overview of autonomic anatomy, classification of cardiovascular, respiratory, sudomotor and thermoregulatory function, bladder, bowel and sexual function. CONCLUSION: This document describes a new system to document the impact of SCI on autonomic function. Based upon current knowledge of the neuroanatomy of autonomic function this paper provides a framework with which to communicate the effects of specific spinal cord injuries on cardiovascular, broncho-pulmonary, sudomotor, bladder, bowel and sexual function.

Higher glucose uptake in paralysed spastic leg.

BACKGROUND: Insulin resistance and diabetes mellitus have been reported in the spinal cord injured (SCI). The group exhibits risk factors, as decreased physical activity, as well as episodes of stimulation of sympathetic nervous system below the level of lesion known to stimulate lipolysis, which in turn could induce insulin resistance. However, data are inconsistent, which might indicate the presence of protective mechanisms. OBJECTIVE: To investigate the glucose uptake in spastic paralysed SCI legs compared to able-bodied. To investigate regional differences between glucose handling in the arm and leg. STUDY DESIGN: Experimental controlled study. SETTINGS: Institution of Clinical Neuroscience and Physiology, Spinal Injures Unit, Sahlgrens University Hospital, Goteborg, Sweden. METHODS: Nine SCI subjects (2 C7, 7 T1-T4 ASIA A: 8, ASIA B: 1) were compared to 10 weight- and age-matched controls. Plasma flow in arm and leg was analysed by venous occlusion strain gauge plethysmography, and plasma derived from artery and veins in the arm and leg was analysed for glucose, insulin and lactate during fasting resting conditions. RESULTS: Glucose uptake was higher in SCI legs compared to controls. There was no difference in insulin uptake or lactate production. Plasma flow was higher in SCI legs compared to controls. Controls showed a higher glucose uptake and lactate production in arm than leg. CONCLUSIONS: Spasticity may counteract the risk of diabetes by inducing an insulin-independent glucose uptake. The regional difference in metabolism in able-bodied make it hazardous to do generalizations to whole body metabolism from arm or leg measurements.

Amenorrhoea in newly spinal cord injured women: an effect of hyperprolactinaemia?

STUDY DESIGN: Prospective, single centre study. OBJECTIVES: Previous studies have suggested a relationship between stress reaction and elevated levels of prolactine. The aim of the present study was to investigate if there was a relationship between s-prolactine and menstrual cycle status following spinal cord injury (SCI). SETTING: Spinal Cord Injury Unit, Göteborg, Sweden. METHODS: S-prolactine and menstrual cycle status were investigated in 16 consecutive women with SCI, treated at the SCI Unit, Sahlgrens University Hospital, Göteborg, Sweden. Level of injury ranged from C1 to L5, ASIA A-D. Mean age at injury was 45 years (range 20-79). RESULTS: S-Prolactine showed a mean value of 741 mIU/l (standard deviation (s.d.): 625; 95% confidence interval (CI): 435-1788 mIU/l, reference value <400 mIU/l). When dividing the group according to fertility status we found hyperprolactinaemia in the women who were in childbearing age (n=9): mean value 1050 mIU/l (s.d.: 678; 95% CI: 607-1493 mIU/ml), whereas it was normal in the group in menopause (n=7): mean value 343 mIU/l (s.d.: 185, 95% CI: 206-480 mIU/l) (P<0.01 when comparing groups). The group that developed amenorrhoea showed the highest values of s-prolactine. All values but one was normalised 3-6 months later. CONCLUSION: Amenorrhoea following SCI is correlated to level of s-prolactine. We found no correlation between level of s-prolactine and level or degree of injury.

Activity performance and upper extremity function in cervical spinal cord injury patients according to the Klein-Bell ADL Scale.

STUDY DESIGN: Cross-sectional study. OBJECTIVES: (1) To examine whether the Klein-Bell ADL Scale (K-B Scale) discriminates cervical spinal cord injury (SCI) patients in daily activities and to explore its applicability in this group of patients. (2) To examine the association between basic ADL and upper extremity function. (3) To investigate if grip ability can be discerned in the scale. SETTING: Spinal Cord Injury Unit, Sahlgrenska University Hospital, Göteborg, Sweden. METHODS: Fifty-five patients with cervical SCI with no prior reconstructive hand surgery were included in the study. Analyses of the patient's independence were made according to the K-B Scale. Three additional analyses were carried out, the first examined whether the use of assistive devices and house and car adaptations influenced independence. The last two used different approaches to investigate whether arm and grip function could be detected in the K-B scale. RESULTS: Raw score in the K-B Scale can discriminate for independence in daily activities but the scale's weight scheme does not function for cervical SCI patients. Assistive devices and car and house adaptations can compensate for dependence in daily activities. Lack of grip function decreases the patient's ability to become independent. Diagnosis-related activities cannot be assessed in all items. CONCLUSION: The K-B Scale's raw score was useful assessing daily activities in cervical SCI patients. Its reliability in conjunction with arm and grip function in patients with cervical SCI has yet to be proven.

Continent cutaneous urinary diversion in patients with spinal cord injury.

STUDY DESIGN: Retrospective study. OBJECTIVE: To examine the functional results and effect on quality of life of continent cutaneous urinary diversion in spinal cord injured patients. SETTING: Department of Urology, Sahlgrenska University Hospital, Göteborg, Sweden. SUBJECTS: A total of 10 patients with spinal cord injury (SCI). METHOD: The patients were operated on with an ileal reservoir (Kock reservoir or T-pouch), Cr-EDTA clearance was determined preoperatively and at follow-up. The patients answered a questionnaire concerning reservoir function, various activities and quality of life. The patient charts were reviewed. RESULTS: One patient died of pulmonary embolism 3 years after surgery. Two patients were reoperated on for reservoir perforation. All patients were satisfied/very satisfied with their reservoirs. Half of them reported improved ability to perform various activities. Eight out of nine patients reported improved quality of life. CONCLUSION: For a selected group of patients with SCI, continent cutaneous urinary diversion provides successful outcome with improved quality of life.

Hyponatremia-induced transient visual disturbances in acute spinal cord injury.

STUDY DESIGN: Case report and literature review. OBJECTIVE: To report an unusual case of prolonged hyponatremia in acute cervical spinal cord injury complicated by visual disturbances and to review the literature regarding the issue. SETTINGS: Spinal Cord Injury Unit in Göteborg, Sweden. METHODS: Retrospective analysis of clinical charts of an individual with traumatic spinal cord injury. RESULTS: A previously healthy 28-year-old man sustained a C7 injury in a motor vehicle accident. His injury was managed surgically and he was overhydrated during the acute management and postoperatively. When weaned off the respirator he was confused and anxious and showed a S-Na of 127 mmol/1 and complained of visual disturbances. The hyponatremia was treated by extra sodium and fluid restriction but fell to a lowest value of 121 mmol/l (Day 14 post injury). Visual acuity was 0.2 on right eye and 0.06 on left eye and the eye examination revealed signs of fundus hypertonicus. CT scans and MRI revealed no signs of brain edema. The patient was further treated by mineral corticoids and fluid restriction for 4 months and his vision improved slightly, but on a final examination 125 days post injury he was found to have an afferent pupillary defect on his left eye, and bilateral atrophy of the visual nerves. The hyponatremia resolved and 6 months post injury he showed a normal S-Na. CONCLUSIONS: SCI individuals are at increased risk of developing hyponatremia. The reported complication of visual disturbances further stresses the importance of prevention of overhydration and of timely management of hyponatremia in this group of patients.

Early interdisciplinary rehabilitation programme for whiplash associated disorders.

PURPOSE: To assess the clinical outcomes of a multidisciplinary rehabilitation programme for early intervention of chronic whiplash associated disorders (WAD). The primary aim of the programme was to increase levels of activity and independence in patients suffering WAD. METHODS: Ninety subjects with purported chronic symptoms associated with whiplash associated disorder (WAD) were referred to a multi-centre multi-modal 5- and 8-week rehabilitation programme in 1997-1998, during which prospective and retrospective functional and psychological evaluations were conducted, the follow-up was to 6 months. RESULTS: Subjects indicated they were satisfied with the programme. Retrospective evaluation indicated increased ability to cope with and control pain and, to some extent, psychological aspects. The pain intensity in the neck and upper back were significantly decreased at 6 months follow-up. However, for most of the functional and psychological markers, no significant changes were found. CONCLUSIONS: A multi-modal rehabilitation programme for the chronic suffering attributed to WAD had positive effects according to several aspects of the retrospective evaluations, but according to most of the aspects evaluated prospectively the programme does not appear to have significant benefits.

Volatiles from apple (Malus domestica) eliciting antennal responses in female codling moth Cydia pomonella (L.) (Lepidoptera: Tortricidae): effect of plant injury and sampling technique.

The antennal responses of codling moth females, Cydia pomonella, to volatiles from apple branches with green fruits were recorded by electroantennography coupled to gas chromatography. The antennae strongly responded to 4,8-dimethyl-1,3(E),7-nonatriene, linalool, beta-caryophyllene, (E)-beta-farnesene, germacrene D, (Z,E)-alpha-farnesene, (E,E)-alpha-farnesene and methyl salicylate. These compounds were all present in volatile collections on Porapak Q from both living and cut branches. Analysis by the solid phase microextraction technique (SPME) showed that the emission of some electrophysiologically active compounds increased after branches had been cut, especially 4,8-dimethyl-1,3(E),7-nonatriene, linalool and (E,E)-alpha-farnesene. The identification of apple volatiles eliciting antennal responses is the first step towards the identification of compounds mediating host-finding and oviposition in codling moth females.

Insulin resistance and sympathetic function in high spinal cord injury.

OBJECTIVE: Cardiovascular disease (CVD) is today one of the main causes of death and affects spinal cord injured (SCI) earlier than able-bodied. Risk factors for CVD, such as decreased glucose tolerance, insulin resistance and increased fat mass, are all reported among SCI subjects and may be related to changes in sympathetic nervous system (SNS) function. METHODS: In order to test our hypothesis of a relationship between metabolic disturbances and alterations in SNS function, glucose and adipose tissue metabolism was investigated by the hyperinsulinaemic normoglycaemic clamp and microdialysis. Body composition was determined by DEXA-scanning. The SNS function was evaluated in total body as well as above and below lesion level by radiolabelled noradrenaline (NA) isotope dilution technique. A 24 h continuous plasma-NA monitoring was performed in seven SCI subjects. RESULTS: Following an oral glucose load the SCI group demonstrated normal glucose tolerance but impaired insulin sensitivity with a maximum insulin value of 83 mU x l(-1) in SCI compared to 50 in siblings, while adipose tissue metabolism was normal compared to siblings. Fat tissue mass constituted 34% of body mass in SCI group compared to 21% in weight-matched controls. Peripheral afferent activation resulted in increased blood pressure, decreased heart rate and reduction in muscle and skin blood flow. Furthermore, lipolysis below lesion level was activated by peripheral stimulation (89-135 micromol x l(-1)). The 24 h continuous monitoring revealed p-NA levels > 1.40 nmol x l(-1) sufficient to induce lipolysis in 20% of the registrations. NA spillover below lesion level increased substantially following peripheral afferent stimulation (0.06-0.90 pmol x min x (-1) x 100 g(-1)), whereas spillover above lesion level increased during central activation. CONCLUSIONS: We found signs of decreased insulin sensitivity and increased fat tissue mass. Peripheral activation of SNS was visualised in the SCI group by increased transmitter spillover as well as increased lipolysis and vasoconstriction. The diurnal registration of NA levels indicated frequent episodes of peripheral sympathetic activation in the group. This may compensate for the inability of central activation of SNS and may contribute to maintain lipolysis activity as well as to generate insulin resistance in the group.

Autonomic dysreflexia.

Autonomic dysreflexia (AD) may complicate spinal cord injured (SCI) subjects with a lesion level above the sixth thoracic level. There are several ways to remove triggering factors and, furthermore, new trigger mechanisms may be added by the introduction of new treatments. New data about the pathogenic mechanisms have been suggested in recent years as well as signs of metabolic effects associated with the reaction. This review of the syndrome includes clinical aspects of the AD reaction; the known pathogenic mechanisms, the incidence and prevalence and triggering factors. AD is associated with some cases of severe morbidity, including cerebral haemorrhage, seizures and pulmonary oedema. Symptomatic as well as specific treatments are discussed. Finally, some further questions are raised by the necessity of a proper definition of the syndrome, the revealing of the underlying pathophysiology, and new investigations concerning incidence and prevalence.

Regional sympathetic function in high spinal cord injury during mental stress and autonomic dysreflexia.

Centrally mediated sympathetic stimulation of subjects who have suffered a spinal cord injury (SCI) does not activate the decentralized part of the body below the level of the lesion, whereas experimental data indicate an exaggerated response above the level of the lesion. SCI subjects may exhibit an autonomic dysreflexia reaction following afferent stimulation below the level of the lesion. In order to investigate the function of the sympathetic nervous system above and below the level of the lesion, regional noradrenaline spillover was measured by means of steady-state isotope dilution technique above (forearm) and below (leg) the level of the lesion at baseline, during mental stress and following bladder stimulation in nine SCI subjects (mean age 41 years; level of injury C7-T4; mean duration of injury 13.8 years). The results from the SCI subjects were also compared with those from 10 weight- and age-matched control subjects, both at rest and during mental stress. Body composition was determined by dual energy X-ray absorptiometry scanning and arm/leg blood flow by occlusion plethysmography. At baseline, total and regional noradrenaline spillover did not differ between the groups. Mental stress increased mean arterial pressure in both groups. Heart rate (76 versus 64 beats/min; P < 0.05) and arm noradrenaline spillover (2.73 versus 1.71 pmol/min/100 g; P < 0.05) increased more in spinal cord injury subjects than in control subjects, whereas total body (2826 versus 3783 pmol/min; P < 0.01) and leg noradrenaline spillover (0.23 versus 0.41 pmol/min/100 g; P < 0.05) increased only in the control group. During bladder stimulation, SCI subjects reacted with a marked increase in mean arterial pressure and leg noradrenaline spillover (from 0.06 to 0.91 pmol/min/100 g; P < 0.05) and their leg blood flow decreased. Regional and total noradrenaline clearance were similar in the two groups. In conclusion, peripheral afferent stimulation below the level of the lesion in spinal cord injury subjects gives rise to a marked noradrenaline spillover from the decentralized part of the sympathetic nervous system suggesting a remaining, but qualitatively altered, neuronal function. Centrally mediated stimulation induced an exaggerated response above the level of the lesion.

Aural rehabilitation in the elderly: supply of hearing aids related to measured need and self-assessed hearing problems.

Three age cohorts of elderly persons in Göteborg (70, 75 and 88 years of age) were studied regarding hearing aid (HA) rehabilitation, on the one hand, and measured and self-assessed hearing, on the other. The participants, 615 in number, were representative of their ages and were selected from a geriatric population study. At age 70, 12% of the participants had been equipped with HAs. At age 75, the corresponding figure was 14% and at age 88, 32%. The correlations between self-assessed and audiometrically measured hearing were reasonably high (r = 0.5-0.7). According to the result for the self-assessed measure, we estimate that elderly persons with pure-tone averages (PTAs) at 30 dB HL (0.5-4 kHz, better ear) are in need of aural rehabilitation. Nevertheless, few subjects with PTAs between 30 and 49 dB HL have been equipped with HAs. At age 88, almost 20% of those with pronounced problems had no HA. Very few participants with no documented hearing problems for aural rehabilitation had been equipped with HAs.

Differentiated norepinephrine spillover in human skeletal muscle.

Most neurophysiological studies have shown similar sympathetic outflow to arm and leg. However, some direct microneurographic recordings indicate differentiated sympathetic outflow to limbs both at rest and during mental stress. Hence, differentiated levels of norepinephrine (NE) spillover could prevail. By steady-state infusion of [3H]NE and body composition determination by dual-energy X-ray absorptiometry-scan, we simultaneously assessed arm and leg NE spillover related to 100 g tissue and total limb weight. NE spillover was lower in leg than arm (0.26 vs. 1.51 pmol.min-1.100 g-1, P < 0.05), and the difference remained when expressed as a function of total limb weight (66 vs. 137 pmol/min, P < 0.05). Fractional extraction of [3H]NE was similar in arm and leg. Neuronal uptake blockade by desipramine was more effective in leg than arm; fractional extraction in leg decreased by 32% (P < 0.05) but was unaltered in arm. Thus a lower NE spillover was observed from leg than arm, possibly reflecting a lower sympathetic outflow and a more neuronally dependent reuptake.

Regulation of lipolysis by the sympathetic nervous system: a microdialysis study in normal and spinal cord-injured subjects.

To evaluate the regulation of lipolysis by the sympathetic nervous system, eight spinal cord-injured (SCI) subjects with a lesion above T5 resulting in a decentralization of the lower-body sympathetic nervous system and adrenal medulla (age, 36 +/- 2 years; weight, 82 +/- 5 kg; body fat mass, 26.8 +/- 3.0 kg; all mean +/- SE) and nine control subjects (age, 33 +/- 2; weight, 80 +/- 3; NS; body fat mass, 16.1 +/- 1.5 kg; P < .01) were investigated after fasting overnight. Each subject was studied with subcutaneous microdialysis and 133Xe-clearance adipose tissue blood flow (ATBF) in the umbilical and clavicular regions during postabsorptive rest and after sympathoexcitatory stimulation by means of mental stress and isometric handgrip exercise. SCI subjects had an increased body fat mass, hyperinsulinemia, and an elevated lipolytic rate at rest compared with control subjects. ATBF and lipolysis were activated to a normal extent following mental stress and isometric handgrip exercise in the umbilical region in control subjects. ATBF was increased in tissue above but not below the lesion level in SCI subjects following mental stress. Glycerol release was not different between groups in either tissue region despite significantly lower noradrenaline and adrenaline levels in SCI subjects. This finding argues against a significant adrenergic control of the lipolytic rate at rest. Furthermore, the small differences in stimulated glycerol release between groups, as well as the increased plasma glycerol levels in SCI subjects, cast doubt on the view that interruption of adrenergic activity below the lesion is the sole mechanism underlying the increased body fat mass in SCI subjects.