bluuebunny/crossref_metadata_2025 huggingface dataset:
Altered balance in the autonomic nervous system in schizophrenic patients
Authors: Nielsen B. M. , Mehlsen J. , Behnke K.
Published: April 2008

Summary. The aim of the present study was to evaluate the autonomic nervous function in schizophrenic patients. Twenty‐eight patients (29 ± 6 years) diagnosed as schizophrenics and in stable medication were included, together with ten schizophrenic patients (25 ± 5 years) who were unmedicated. Eleven healthy subjects (32 ± 7 years) served as controls. Immediate heart‐rate responses to a single deep inspiration was used as a measure of parasympathetic function. Heart‐rate response to standing was used as a measure of sympathetic function. Supine blood pressure, heart‐rate and orthostatic changes in blood pressure did not differ between groups. Heart‐rate response to standing was greater in both medicated and non‐medicated schizophrenics compared to normal subjects (P<0·01). Heart‐rate response to standing was greater in non‐medicated compared to medicated schizophrenics (P<0·05). Heart‐rate response to inspiration was greater in non‐medicated schizophrenics compared to normal subjects (P<0·05), whereas no difference was found between medicated and non‐medicated schizophrenics. The results show that the balance in the autonomic nervous system is altered in schizophrenic patients with a hyperexcitability in both the sympathetic and the parasympathetic division. Our study has thus indicated a dysfunction in the autonomic nervous system per se and the previous interpretations of attentional orienting responses in schizophrenia is questioned. Medication with neuroleptics seems to partly normalize the autonomic reactivity rather than being the cause of autonomic dysfunction.
Plasma dihydroxyphenylglycol (DHPG) as an index of diabetic autonomic neuropathy
Authors: Christensen N. J. , Dejgaard A. , Hilsted J.
Published: April 2008

Summary. Forearm venous plasma noradrenalin and dihydroxyphenylglycol (DHPG) concentrations were measured in eight diabetic patients with and eight diabetic patients without neuropathy. Plasma noradrenalin was on average the same in patients with and without neuropathy and correlated to serum creatinine. Plasma DHPG concentrations were significantly reduced in patients with autonomic neuropathy as compared to patients without neuropathy (P<0·05). A low plasma DHPG/noradrenalin ratio in forearm venous blood identified all patients with autonomic neuropathy except one (P<0·02). Measuring the plasma DHPG/noradrenalin ratio may circumvent the problem of unrepresentative noradrenalin release from the forearm.
Role of pulmonary diseases and physical condition in the regulation of vasoactive hormones
Authors: Hietanen E. , Marniemi J. , Liippo K. , Seppänen A. , Hartiala J. , Viinamäki O.
Published: April 2008

Summary. Lungs have many non‐respiratory metabolic functions, of which some take place in the capillary endothelium, while others are in parenchymal lung tissue. We have studied the role of the lungs in the metabolism of vasoactive and some other hormones by comparing patients who have undergone lung resection to those having various obstructive or fibrotic lung diseases. We have also compared these groups with persons in good physical health. The data suggested that lung resection patients had low angiotensin II levels in plasma but the response of angiotensin II to exercise was normal. Also adrenalin concentration was low in the lung resection group while dopamine did not show any significant difference between the groups. When hormone levels were correlated to the exercise data, renin levels were especially related to physical condition. Serum post‐exercise renin values were inversely related to the uneven distribution of lung perfusion, possibly thus reflecting the diminished pulmonary vascularization. A negative association was found between angiotensin II and diffusion capacity. Thus, the angiotensin II levels may preferably be controlled by the non‐circulatory functions of the lungs.
Angiotensin II attenuates reflex decrease in heart rate and sympathetic activity in man
Authors: Sander‐Jensen K. , Secher N. H. , Astrup A. , Christensen N. J. , Damkjær‐Nielsen M. , Giese J. , Warberg J. , Bie P.
Published: April 2008

Summary. Circulatory variables and hormone concentrations in arterial plasma were measured in six normal subjects during angiotensin II (ANG II) step‐up infusion of 0·25 and 1·00 ng kg‐1× min. During the 1·00 ng kg‐1× min infusion ANG II plasma concentrations increased from 11 ± 2 to 48 ± 6 pg ml‐1; i.e., similar to those obtained during acute hypotensive hypovolemia in man. Mean arterial pressure increased (P<0·05) from a resting value of 89±3 to 97±5 mmHg. Heart rate and catecholamine concentrations did not change. Plasma aldosterone increased (P<0·05) from 36 ± 4 to 77 ± 10 pg ml‐1 during the infusion. Plasma concentrations of vasopressin, adrenalin and pancreatic polypeptide did not change during the investigation. During the 0·25 and 1·00 ng kg‐1× min infusion subcutaneous blood flow decreased (P= 0·06) to 67 ±20 and 66 ±26%, respectively, of control.

It is concluded that: (1) ANG II in physiological doses in man may augment the sympathetic activity on the circulatory system since compensatory decreases in heart rate or in plasma catecholamines were not observed during the increased arterial pressure; (2) ANG II does not induce a general decrease in vagal tone as plasma pancreatic polypeptide concentrations were unchanged; (3) the obtained plasma concentrations of ANG II do not stimulate the release of vasopressin to plasma; and (4) the threshold for reducing the subcutaneous blood flow is reached within relatively small increments in plasma ANG II.
Left ventricular volumes during graded upright exercise in healthy untrained subjects
Authors: Kelbæk H. , Christensen N. J. , Godtfredsen J.
Published: April 2008

Summary. Left ventricular (LV) volume changes were studied by radionuclide cardiography at rest and during graded upright bicycle exercise in seven healthy untrained men aged 21–30 years. The exercise‐induced changes in LV volumes were most pronounced during mild exercise: from rest to 25% submaximal exercise stroke volume increased by 26% and LV ejection fraction from 0·60 to 0·69 (both P<0·01), whereas further increments of the work load resulted in only small changes of these variables. LV end‐diastolic volume increased initially by 10% (P<0·05) but returned to baseline values at higher work loads, whilst a rather constant decrease was recorded in LV end‐systolic volume during increasing exercise loads.

Changes in plasma catecholamine levels were most pronounced at the high work loads, indicating that these hormones are not directly contributing to the LV volume changes.
Leg exchange of amino acids during exercise in patients with arterial insufficiency
Authors: Lundgren F. , Zachrisson H. , Emery P. , Bylund‐Fellenius A.‐C. , Elander A. , Bennegård K. , Scherstén T. , Lundholm K.
Published: April 2008

Intermittent claudication is associated with adaptation in muscle metabolism. This study has evaluated the metabolism of amino acids at rest and during non‐steady state exercise in patients with arterial insufficiency of at least six months duration in comparison with matched control individuals. The exchange of amino acids were measured during two periods of acute exercise; one initial exercise period with a standardized work load and exercise time and a second exercise period which continued until further exercise was impossible due to pain in the patients and exhaustion in the controls.

The maximum blood flow was reduced by 40% in the patients but the maximum oxygen uptake per unit power developed was almost the same in patients and controls. The patients had significantly lower concentrations of glutamine, lysine and taurine at rest compared with the controls. The exchange of amino acids across the resting leg did not differ between the two groups. Exercise increased the efflux of amino acids in both patients and controls. The efflux of glutamine (896 ± 205 vs. 48 ± 359 nmol/100 ml/min/watt) was higher in the patients compared to the controls at the first exercise period with inverse changes in the opposite direction of asparagine (149 ± 105 vs. 799 ± 121 and 27 ± 70 vs. 633 ± 334 nmol/100 ml/min/watt at the first and second exercise, respectively. Alanine release did not differ between the groups. The complementary patterns of glutamine and asparagine during hypoxic exercise in the patients may reflect the fact that these amino acids share a common carrier system. The similarity in the efflux of non‐metabolized amino acids, such as methionine, phenylalanine, tyrosine and 3‐methylhistidine, indicated that muscle hypoxia in claudication patients did not promote net degradation of either globular or myofibrillar proteins, although exercise increased the efflux of 3‐methylhistidine three‐ to fourfold in both patients and control individuals (from 1 ± 0·4 to 4 ± 1·8 and from 0 ± 0·7 to 6 ± 2·5 nmol/100 ml/min/watt, respectively). The exercise‐induced alterations in leg exchange of amino acids were restored within 10–20 min following exercise regardless of hypoxia.

The results demonstrate that patients with arterial insufficiency have altered intermediary metabolism of amino acids during exercise. However, muscle hypoxia in such patients does not seem to promote a negative protein balance or induce serious alterations in cell membrane integrity.
Cardiovascular effects of positive end‐expiratory pressure during acute left ventricular failure in dogs
Authors: Hevrøy O. , Reikerås O. , Grundnes O. , Mjøs O. D.
Published: April 2008

Haemodynamic and metabolic effects of ventilation with positive end‐expiratory pressure (PEEP) were studied in closed‐chest dogs anaesthetized with sodium pentobarbital during normal cardiac function and during acute left ventricular (LV) failure. LV failure was induced by embolizing the left coronary bed with 50 μm plastic microspheres causing a marked depression of LV function. End‐expiratory pressure was set to 0, 5, 10 and 15 cm H2O both before and after coronary embolization. During normal cardiac function PEEP above 5 cm H2O depressed cardiac output (CO) significantly. However, following coronary embolization after which LV function was seriously impaired, CO was maintained as PEEP was applied. This is attributed to reduced sensitivity to the LV pre‐load reductions induced by PEEP during LV failure. PEEP reduced MBF both during normal and impaired LV function. This did not result in ischaemic myocardial metabolism assessed by lactate extraction either in normal hearts or following coronary embolization. The reduced MBF was, however, associated with reduced MV̇O2 both during normal cardiac function and during LV failure. It is suggested that the reduced MBF is mainly due to reduced myocardial oxygen demand probably caused by reduced LV wall tension during PEEP ventilation.
Density dependence of expiratory flow—a useful basis for lung function tests?
Authors: Sixt R. , Bake B.
Published: April 2008

The aim of this investigation was to study the density dependence of forced expiratory flow and the ability of tests based on density dependence to disclose smoking‐induced small airways dysfunction. The lung function of 212 systematically sampled men (mean age 40·3; range 30–48 years) was studied by recording flow‐volume curves during air or helium‐oxygen (HeOx) breathing and by the single breath N2‐test.

Density dependence was expressed as the percentage increase in flow from air to HeOx when 50 and when 25% of the vital capacity (VC) remained to be expelled (dMEF50 and dMEF25).

The mean dMEF50 in 59 healthy non‐smokers was 40% (range+7 to +72) and the mean dMEF25 24% (range ‐20 to +63). Density dependence apparently decreased with relative lung volume and also with increasing age.

Despite the wide variation of density dependence in the reference group, dMEF50 was on average significantly reduced in smokers, and dMEF25 in ex‐smokers and subjects with symptoms such as cough and/or sputum production, wheezing unrelated to common colds and dyspnea when walking on level ground. However, only 8% of the smokers exhibited ‘abnormal’ density dependence (dMEF25 < (predicted value— 2RSD)) as compared to 11 and 33% for the forced expiratory volume in one second (FEV1) and dN2 (alveolar slope).

If abnormal dN2 in the smoking group is taken to indicate smoking‐induced small airway dysfunction, then the ability of dMEF50 and dMEF25 to disclose such dysfunction is limited.
Does airway closure affect lung sound generation?
Authors: Bohadana A. B. , Kanga J. F. , Kraman S. S.
Published: April 2008

Summary. The purpose of this experiment was to test the hypothesis that airway closure impedes the production of lung sounds at low lung volume. We recorded breath sounds in three healthy men during inspiratory vital capacity manoeuvres in upright, head‐down and lateral decubitus postures. We then compared the rate of increase of breath sound intensity (BSI) between the dependent and non‐dependent lung zones. Closing volumes, measured separately, were normal in the upright but increased in the head‐down postures. The data revealed no consistent lag in the rate of increase of BSI over the dependent lung zones in any of the postures. Our data suggest that airway closure does not influence lung sound generation. If true, this implies that lung sounds are produced proximally to the site of physiologic airway closure.
Cardiac function in open‐chest dogs after left to right ventricular shunting and right coronary artery occlusion
Authors: Geiran O. , Thorvaldson J. , Ilebekk A.
Published: April 2008

Summary. Patients with acquired ventricular septal defect (VSD) after myocardial infarction have a particularly bad prognosis if right ventricular function is severely impaired. The significance of an ischaemic right ventricular free wall on cardiac function during interventricular shunting was examined in open‐chest dogs. An external interventricular shunt could be opened and closed at will, and by occlusion of the right coronary artery (RCA), a part of the right ventricular free wall was rendered ischaemic. Aortic flow decreased by 8±2% when the shunt was opened in the presence of a normal right ventricle, and by 16±2% (difference: P<0.05) in the presence of right ventricular ischaemia. Aortic flow fell by 19±3% when the RCA was occluded. Right ventricular dyskinesia was demonstrated after occlusion of RCA, by recording segment lengths in the right ventricular free wall. The dyskinesia was aggravated when the shunt was opened. The left ventricle exerted a ‘negative’ work on the ischaemic right ventricular free wall. Retention of blood in the right ventricle, with a subsequent decline in left ventricular filling and an almost unchanged interventricular shunting of blood, explain why aortic flow fell more when the shunt was opened in the presence of right ventricular ischaemia.
Plasma renin activity and oxygen content along the renal veins in hypertensive patients
Authors: Tidgren B. , Brodin U.
Published: April 2008

Summary. Plasma renin activity (PRA) and oxygen content in three different locations in the renal veins were studied in 27 patients with suspected renin‐dependent hypertension or during post‐operative follow‐up investigations after renal artery reconstruction. A significant decrease in PRA was found along the right renal vein but not along the left one. The oxygen content simultaneously measured was lower in the central parts of both renal veins than most peripherally, more on the right side than on the left one, indicating dilution of renal venous blood.

An erroneous ratio between renal vein PRA of the affected and the contralateral kidney was found in two of 17 patients with unilateral renal artery stenosis when sampling from a central position in the renal vein. This indicates that a peripheral position of the catheter is important when sampling for renal vein PRA.
The veno‐arteriolar reflex in free skin flaps
Authors: Zoltie N. , Young C. , Faris I. , Tan E.
Published: April 2008

Summary. The veno‐arteriolar reflex was measured in 10 subjects in whom an area of denervated skin was present in the lower limb following free flap transfer of skin and subcutaneous tissue 3 weeks to 2 years previously. The vasoconstrictor response to dependency was measured in the skin of the flap, in adjacent innervated skin and after chemical dilatation of cutaneous vessels in the skin of the flap. This veno‐arteriolar reflex resulting in a reduction of blood flow of 30–40% was present and equal in both normal and denervated skin. The response was abolished by chemical vasodilatation.

The results indicate that sympathetic innervation is not essential for the venoarteriolar reflex, and suggest that myogenic mechanisms may be more important than previously believed.
Arterio‐venous concentration difference of [51Cr]EDTA after a single injection in man. Significance of renal function and local blood flow
Authors: Rehling M. , Hyldstrup L. , Henriksen J. H.
Published: April 2008

Summary. The present investigation was undertaken in order to study (1) the difference in arterial (Ca) and venous (Cv) concentration of [51Cr]EDTA (ethylenediaminetetra‐acetate) after a single intravenous injection, (2) the impact of different physiological variables on this difference, and (3) the error introduced in the measurement of renal plasma clearance and total plasma clearance by using venous blood samples instead of arterial.

In 13 patients with GFR ranging from 29 to 150 ml min‐1, Ca was higher than Cv immediately after the injection. After mean 38 min (range 12–82 min) the two curves crossed, and 180–300 min post‐injection (p.i.) Cv was 5·9% higher than Ca (range 0·5–13·9%, P<0·001). The more reduced renal function, the smaller was the concentration difference. The areas under the arterial and the venous plasma concentration curves did not differ significantly at either 0–∞ or 0–300 min p.i., whereas the venous area 0–100 min p.i. underestimated the arterial area in the same period by 4·1% (P<0·05).

In a computer simulation model, variation in the forearm capillary permeability–surface area product did not have any significant influence on the Cv–Ca difference, whereas the difference was very sensitive to even small changes in forearm blood flow within the physiological range.

For measurement of renal plasma clearance it is recommended to use one long period: from the time of injection until 300 min p.i. or longer. If the clearance period is too short, the use of venous samples will overestimate the true renal clearance. Plasma clearance determined by venous and arterial blood samples does not differ significantly as long as the concentration is followed from the time of injection and a long period is applied. When simplified plasma clearance techniques are used, different results may be obtained from venous and arterial samples. The simplified techniques using venous blood samples—which usually include some empirical corrections—should be sufficiently reliable in daily clinical practice provided the forearm blood flow is reasonably high, e.g. exposure to cold should be avoided.
Does mitochondrial compartmentation of CO2 exist in man?
Authors: Fuller N. J. , Elia M.
Published: April 2008

Summary. A comparison was made between the specific radioactivity of urea, and that of CO2 in breath, in urine and in arterialized blood, during a 36‐h continuous infusion of 0.5 mCi and 100 mmol of sodium bicarbonate (NaH14CO3) into six normal male volunteers. After a period of equilibration, the mean specific radioactivity of urea was found to be only 16% below that of end expiratory CO2 and a similar amount below that of CO2 both in arterialized blood and in urine. This difference may be explained by isotopic dilution of 14CO2 by metabolic CO2 produced in the splanchnic tissues. It is concluded that, in these normal subjects, there is little or no compartmentation between cytosolic CO2 and the mitochondrial CO2 used for urea synthesis.
Chest pain and oesophageal pressure relationships in man following an intravenous bolus of adenosine
Authors: Melcher A. , Sylvén C.
Published: April 2008

Summary. After titration of maximum tolerable i.v. bolus dose of adenosine, this dose was given to seven volunteers (20–42 years), instrumented with a three‐lumen oesophageal pressure catheter with recording sites at the levels of the stomach, the lower oesophageal sphincter (LOS) and the oesophagus. In addition to continuous pressure recordings, chest pain was estimated continuously by a 10‐graded category–ratio scale.

Baseline resting pressures were 8·4 (1·9) mmHg in the stomach, 1·6 (1·7) mmHg in the oesophagus and 20 (2·6) mmHg in the LOS resulting in a net LOS pressure of 11 (± 1·3) mmHg. Following injection of adenosine which provoked transient chest pain with a rated maximum of 5·4 (1·0), resting oesophageal pressure did not change while net LOS pressure decreased to – 1·3 (1·9) mmHg (P<0·0001). Adenosine injection did not affect swallowing‐induced peristaltic contractions of the oesophagus and LOS although the peristaltic wave was delayed (P<0·05). Thus, chest pain evoked by adenosine cannot be caused by spastic oesophageal contractions. Adenosine may have a relaxing effect on the LOS but does not block its normal reactions to swallowing.
Atrial natriuretic factor during exercise in male endurance athletes: effect of training
Authors: Vollmer‐Larsen B. , Vollmer‐Larsen A. , Larsen O. Graff , Breum L. , Larsen J. , Keller N.
Published: April 2008

Summary. Nine male endurance runners were evaluated with bicycle exercise testing before a training break of 3 weeks duration, and 0, 2 and 4 weeks after resumption of training to assess the effects of training on resting and exercise plasma atrial natriuretic factor (ANF) measured at 50% and 100% of predetermined maximal workload. Maximal oxygen uptake and lean body mass (LBM) were calculated at each time point. Maximal oxygen uptake decreased during training break, but rose 4 weeks after resumption of training (P<0·01). LBM was unchanged after inactivity, but rose after resumption of training (P<0·01). Plasma ANF at rest did not change throughout the experiment. ANF levels rose after training break at maximal workload (P<0·05), and decreased 4 weeks after resumption of training, but only at submaximal workload (P<0·05). No correlations between systolic blood pressure, mean blood pressure or heart rate and ANF could be demonstrated. These results indicate that the haemodynamic changes associated with endurance training are reflected in plasma ANF levels during exercise, but not at rest. The full adaptation of ANF release to training probably requires more time than the 4 weeks reported for the haemodynamic adjustments.
Fluorescein angiography and distal arterial pressure in patients with arterial disease of the legs
Authors: Wallin L. , Lund F. , Westling H.
Published: April 2008

Summary. Fluorescein angiography (FA) of the foot soles was performed in 119 patients with arterial disease of the legs. Fluorescein was injected rapidly intravenously and sequential photographs were taken of the foot soles. Densitometric measurements were performed on three areas of each foot image: the big toe, the foot pad (just proximal to the little toe) and the heel. The relationships between different FA measurements and systolic arterial pressure in the ankle or the big toe were analysed.

The appearance times of fluorescence correlated inversely with ankle pressure (P<0·001). The initial slopes of the fluorescence–time curves at all three sites of measurement correlated with ankle pressure (P<0·001). The initial slopes of fluorescence–time curves of the big toe and the foot pad correlated with toe pressure (P<0·001).

In 12 patients effective arterial pressure was lowered by elevation of the feet, and in eight patients external pressure was applied to the foot by enclosing it in a box. The changes in FA evoked by these manoeuvres further strengthened the relationship between arterial pressures and FA measurements.

We conclude that FA is a good method for evaluating circulation in the foot when neither ankle nor toe pressure is obtainable. In addition, FA may be useful when vascular disease is suspected in the presence of normal pressures, because the fluorescence distribution pattern was clearly abnormal in 11 of 16 such feet.
Role of leg vasculature in the cardiovascular response to arm work in wheelchair‐dependent populations
Authors: Kinzer S. M. , Convertino V. A.
Published: April 2008

Summary. To assess the effects of leg vasculature on cardiovascular dynamics during submaximal arm work, oxygen uptake (V̇o2), cardiac output (Q̇) and heart rate (HR) were measured during arm‐crank ergometry (ACE) at 35 W (45% peak ACE V̇o2) in five able‐bodied subjects, five wheelchair‐dependent paraplegics, and five wheelchair‐dependent bilateral amputees who represented the conditions of active, passive, and absence of leg musculature respectively. Arteriovenous oxygen difference (a—v̇ O2) and stroke volume (SV) were calculated from V̇o2, Q̇ and HR. An index of leg fluid accumulation and leg blood flow was measured in the paraplegics and able‐bodied subjects during rest and ACE. V̇o2, Q̇, and a‐v̇ O2 during ACE were not statistically different among the three groups. However, paraplegics exhibited higher HR (P< 0.05) and lower SV (P < 0.06) during exercise compared to both amputees and able‐bodied subjects. Greater (P < 0.05) leg fluid accumulation was measured in paraplegics compared to able‐bodied subjects, although no statistically significant differences in leg blood flow were observed. Although our results are limited to a small number of subjects, these data suggest that an active muscle pump contributes significantly to elevated venous return and stroke volume during ACE. The legs of the paraplegic appear to act as a reservoir for fluid accumulation which may limit cardiac filling, particularly during moderate arm work to support wheelchair function.
Haemodynamic and ADH responses to central blood volume shifts in cardiac‐denervated humans
Authors: Convertino V. A. , Thompson C. A. , Benjamin B. A. , Keil L. C. , Savin W. M. , Gordon E. P. , Haskell W. L. , Schroeder J. S. , Sandler H.
Published: April 2008

Summary. Haemodynamic responses and antidiuretic hormone (ADH) were measured during body position changes designed to induce blood volume shifts in 10 cardiac transplant recipients to assess the contribution of cardiac and vascular volume receptors in the control of ADH secretion. Each subject underwent 15 min of a control period in the seated posture, then assumed a lying posture for 30 min at 6° head‐down tilt (HDT) followed by 30 min of seated recovery. Venous blood samples and cardiac dimensions (echocardiography) were taken at 0 and 15 min before HDT, 5, 15 and 30 min of HDT, and 5, 15 and 30 min of seated recovery. Blood samples were analysed for haematocrit, plasma osmolality, plasma renin activity (PRA) and ADH. Resting plasma volume (PV) was measured by Evans blue dye and per cent changes in PV during posture changes were calculated from changes in haematocrit. Heart rate (HR) and blood pressure (BP) were recorded every 2 min. In the cardiac transplant subjects, mean HR decreased (P<0·05) from 102 b.p.m. pre‐HDT to 94 b.p.m. during HDT and returned to 101 b.p.m. in seated recovery while BP was slightly elevated (P<0·05). PV was increased by 6·3% (P<0·05) by the end of 30 min of HDT but returned to pre‐HDT levels following seated recovery. Plasma osmolality was not altered by posture changes. Mean left ventricular end‐diastolic volume increased (P<0·05) from 90 ±5 ml pre‐HDT to 105 ±4 ml during HDT and returned to 88 ±5 ml in seated recovery. Plasma ADH was reduced by 28% (P<0·05) by the end of HDT and returned to pre‐HDT levels with seated recovery. PRA was also reduced by 28% (P<0·05) with HDT. These responses were similar to those of six normal cardiac‐innervated control subjects and one heart‐lung recipient. Therefore, cardiac volume receptors are not the only mechanism for the control of ADH release during acute blood volume shifts in man.
Pulmonary clearance of inhaled 99Tcm‐DTPA: significance of site of aerosol deposition
Authors: Groth S. , Hermansen F. , Rossing N.
Published: April 2008

Summary. The aim of this study was to analyse how changes in the site of 99Tcm‐DTPA aerosol deposition between central and peripheral parts of the lung influence routine measurement of pulmonary clearance of 99Tcm‐DTPA (PCl). The study was performed in six ‘never‐smokers’ and 10 smokers with bronchial hypersecretion. Changes in aerosol deposition was accomplished by changing the aerosol particle size and the velocity by which the subjects inhaled the particles. In the smokers with bronchial hypersecretion there was a significantly smaller PCI after central deposition (P< 0·01), than after peripheral deposition, while in the never‐smokers, significance was not reached. The smokers with bronchial hypersecretion had a significantly higher PCI than the never‐smokers (P<0·01) when the 99Tcm‐DTPA had been deposited in the peripheral parts of the lung, but at the examination of central deposition, the difference was no longer significant. It is concluded that in smokers with bronchial hypersecretion measurement of regional PCl is influenced by the site of 99Tcm‐DTPA deposition in the lung.
The effect of sympathetic blockade and cooling in Raynaud's phenomenon
Authors: Engelhart M.
Published: April 2008

Summary.Nineteen patients with Raynaud's phenomenon (12 suffering from generalized scleroderma [GS] and seven from primary Raynaud's phenomenon [PR] and seven cold‐tolerant healthy women underwent a cooling challenge with combined body and finger cooling. Finger systolic blood pressure was measured at 30 and 15°C, before and after nervous blockade at the finger‐base with lidocain. Finger/arm blood pressure ratio (FBP/armBP) at 30°C was significantly lower in GS as compared to controls and PR, and it did not change after nervous blockade in any group. FBP/armBP at 15°C, decreased to zero in all patients with Raynaud's phenomenon and to median 0–67 in controls, prior to nervous blockade. After nervous blockade, in response to cooling, FBP/armBP at 15°C decreased significantly and was comparable in all groups.

We conclude that the sympathetic nervous system seems to play an important part in provoking Raynaud's phenomenon in PR and most GS.
Neuropeptide Y is released together with noradrenaline from the human heart during exercise and hypoxia
Authors: Kaijser L. , Pernow J. , Berglund B. , Lundberg J. M.
Published: April 2008

Summary. The myocardial release of neuropeptide Y‐like immunoreactivity (NPY‐LI) and noradrenaline (NA) during exercise with and without arterial hypoxia was measured in 18 healthy men by arterial (a) and coronary sinus (cs) catheterization. Exercise was performed in the supine position on a cycle ergometer at a load, selected to produce a heart rate during air breathing of 120 beats min‐1. Coronary sinus blood flow (CSBF) was measured and a and cs samples for NPY‐LI, NA, oxygen and lactate analyses were taken at rest and after 6 min exercise. The inspiratory gas was then switched to 15% (n= 8) or 12% (n= 10) oxygen in nitrogen, exercise continued at the same load and measurements repeated after 6 min. At rest no significant release and during normoxic exercise a very small myocardial release of NPY‐LI and NA was detected. During hypoxia compared to normoxia the cardiac NPY‐LI release increased four‐fold and the NA net release doubled at the same time as the arterial NPY‐LI remained unaltered or only slightly increased. Both the NPY‐LI and the NA net release from the heart correlated with the heart rate and the arterial but not the cs oxygen tension. The NPY‐LI release was correlated with the NA net release. The findings suggest that arterial hypoxia stimulates cardiac NPY together with NA release which derives from local sympathetic nerves. The release from the heart seems to be greater than from other tissues.
Influence of combined intravenous and oral glucose administration on splanchnic glucose uptake in man
Authors: Ferrannini E. , Katz L. D. , Glickman M. G. , Defronzo R. A.
Published: April 2008

Summary. The influence of intravenous plus oral glucose administration on splanchnic glucose handling was examined in healthy young individuals by combining the hepatic vein catheterization technique with the double glucose tracer method. After 1 h of steady state hyperglycaemia (11·7 Itim) induced by intravenous glucose alone (hyperglycaemic clamp technique), subjects ingested 89 ± 1 g of glucose, and the hyper‐glycaemic plateau was maintained for the subsequent 4 h by adjusting the exogenous glucose infusion rate. Over the 4‐h absorptive period, only 51 ± 4 g of oral glucose (i.e. 58 ±4% of the ingested load) appeared in the systemic circulation, while 193 ± 15 g (1·072±0·083 mol) of glucose had to be infused exogenously to sustain the hyperglycaemia. Endogenous glucose production was suppressed by over 60%. Net splanchnic glucose balance switched from a positive value (i.e. net uptake) of 506 ± 2–56 uniol min‐1kg‐1with intravenous glucose alone (0·60 min) to a negative one (i.e. net output) of 12·50 ± 2·44 u. mol min‐1kg‐1during 4 h (60–300 min) of intravenous+oral glucose. The mean rate of splanchnic glucose uptake was estimated to be 6·39 ±4·67 ixmol min‐1kg‐1with intravenous glucose alone, and 8·83 ±4·28 u. mol min‐1kg‐1with intravenous+oral glucose. In either case, the large majority (80–90%) of the glucose appearing in the systemic circulation was disposed of by extrasplanchnic tissues. These results indicate that pre‐existing hyperglycaemia and/or hyperinsulinaemia inhibit gastrointestinal glucose absorption, and that oral glucose administration does not result in a major redistribution of intravenous glucose between splanchnic and extrasplanchnic tissues.
Mucociliary clearance in healthy men at rest and during exercise
Authors: Olséni L. , Wollmer P.
Published: April 2008

Summary. We measured mucociliary clearance at rest and during exercise in 11 healthy non‐smoking men. The subjects inhaled an aerosol containing [99Tcm]albumin millimicrospheres with deep inhalations. Four sets of scintigraphic images were obtained with 15‐min intervals. Lung retention of radioactivity was quantified using a gamma camera and the clearance of particles from the lungs calculated for each 15‐min period. The first image was obtained directly after inhalation, the second after a period of 15‐min rest, the third after a period of exercise on a bicycle ergometer (workload approximately 80% of predicted maximum capacity) and the final fourth image after another period of rest. We found small differences in clearance rate at rest and during exercise indicating that there is no substantial change in the clearance rate during exercise in normal subjects.
Effect of acquisition and analysis routines on gated blood pool measurements
Authors: Brodin L.‐Å. , Bone D. E.
Published: April 2008

Summary. Results obtained from gated equilibrium blood pool (GBP) studies are not only dependent on intrinsic variations, but also on the way in which images are acquired and analysed. The aim of this study was to investigate factors which could affect left ventricular time‐activity curves.

Temporal resolution was studied by comparing studies of 20 and 40 frames beat‐1. Forty frames per beat resulted in a mean left ventricular ejection fraction of 0.48 compared to 0.46 for 20 frames beat‐1. The mean difference of 0.02 was significant (P<0.01) as was the mean difference in maximum emptying rate (MER = 0.28, P<0.01) and in maximum filling rate (MFR = 0.38, P<0.01).

No significant differences in ejection fraction (EF) values were found between acquisitions made in list and frame mode, but the mean differences for MER = 0.03 (P<0.05) and MFR = 0.01 (P<0.02) were significant. For patient repositioning and intra‐observer variations no significant differences were found.

In patients with normal EF values (>0.5) no significant differences were found in the inter‐observer study. In patients with anterior myocardial infarction (AMI), significant differences were found in EF, MER and MFR (EF = 0.02, P<0.001; MER = 0.2, P<0.‐01; MFR = 0.24, P<0.01).

Significant differences were found in all values when comparing a semi‐automatic method of evaluation with two automatic methods.

In conclusion the results from this study suggest that acceptable reproducibility can be achieved in GBP studies, provided the method of analysis is not changed between studies.
Nailfold capillaroscopy in non‐insulin dependent diabetes mellitus: blood flow velocity during rest and post‐occlusive reactive hyperaemia
Authors: Pazos‐Moura C. C. , Moura E. G. , Bouskela E. , Filho I. P. Torres , Breitenbach M. M. D.
Published: April 2008

Summary.Direct intravital microscopic examinations of nailfold capillaries were made in two groups of subjects: 15 healthy volunteers (C) and 16 non‐insulin dependent (D II) diabetic patients. In the diabetic group, the disease duration was less than 1 year (n= 4), between 1 and 10 nyears (n= 8) and between 10 and 18 years (n= 4). Capillary morphology was evaluated and the distribution of morphological patterns was significantly different between the two groups (P<0.001). The number of enlarged capillaries was increased in the D II group compared to the C group and capillaries with nodular apical elongations were only found in diabetics. Capillary blood flow velocity (CBFV) was measured during rest and after release of 60 s arterial occlusion. To assess autoregulatory capacity we determined peak CBFV post occlusion and time to reach it in single capillaries. Mean resting CBFV was not statistically different in the two groups but mean peak CBFV post occlusion was significantly lower (C: 1.49±0.14 mm s‐1; mean±SE; D II: 0.93±0.13 mm s‐1, (P<0.05) and mean time to reach it significantly prolonged (C: 8.9±0.6 s; D II: 18.0± 1.9 s;P<0.05) in diabetics compared to controls. Thus skin microvascular autoregulatory responses are disturbed in these patients. The impairments of the reactive hyperaemia response could not be correlated to either metabolic control or duration of the disease.
Plasma levels of atrial natriuretic peptide at rest and during exercise in heart failure—influence of cardiac rhythm and haemodynamics
Authors: Berglund H. , Jensen‐Urstad M. , Theodorsson E. , Bevegård S.
Published: April 2008

Summary. The relationship between plasma levels of immunoreactive atrial natriuretic peptide (ir‐ANP), arginine vasopressin (AVP), cardiac rhythm and different haemodynamic variables were studied at rest and during exercise in 16 patients with heart failure undergoing heart catheterization for clinically indicated reasons.

Even though there was no significant relationship between pulmonary capillary wedge pressure (PCW) and ir‐ANP at rest (r= 0·39; P= 0·14) changes in these variables with exercise correlated well (r= 0·71; P= 0·002). Change in right atrial mean pressure, heart rate, mean arterial blood pressure or cardiac index did not significantly influence change in plasma levels of ir‐ANP. The correlation between PCW and AVP at rest (r= 0·92; P<<0·001) disappeared during exercise. Calculated ir‐ANP/PCW ratios decreased slightly during exercise, but were not influenced by initial atrial pressures or atrial fibrillation.

These observations provide evidence for a similar responsiveness of ANP in patients with sinus rhythm and atrial fibrillation. The ability of rapid change in ANP plasma levels during exercise was preserved and proportional to changes in PCW over a wide pressure range in the studied patient group. This finding indicates that left atrium distension rather than right atrium distension is the major determinant for the release of ANP in patients with congestive heart failure. The observed rapid responsiveness of ANP to change in left atrial pressure may allow the hormone to modulate haemodynamic response during short periods of exercise.
Pulmonary vasodilatation and augmentation of right ventricular function following terbutaline infusion in severe chronic pulmonary disease
Authors: Eliasen K. , Ringsted C. , Munck O. , Hjortsø E. , Heslet L.
Published: April 2008

Summary. Twenty patients with a median age of 61 years and a median forced expired volume in 1 s (FEV1) after bronchodilatating therapy of 0·55 1 were studied in order to measure the effect of intravenous terbutaline on bronchial tone, cardiac function, pulmonary haemodynamics, gas exchange, and oxygen transport capacity during rest and in 10 patients during exercise.

Terbutaline infusion during rest resulted in an increase in heart rate from 84 to 103 beats min‐1 (P < 0·01), a decrease in mean systemic arterial pressure from 95 to 80 mmHg (P < 0·02), an unchanged mean pulmonary arterial pressure (18 mmHg), an increase in cardiac index from 2·89 to 3·86 1 min‐1 m‐2 (P < 0·01), an increase in right ventricular ejection fraction from 45 to 53% (P < 0·01), an increase in left ventricular ejection fraction from 63 to 67% (NS), an unchanged arterial oxygen tension, and an increase in calculated oxygen delivery from 533 to 638 ml O2 min‐1 m‐2 (P < 0·01). During exercise terbutaline infusion resulted in an increase in heart rate from 108 to 120 beats min‐1 (P < 0·05), a decrease in mean systemic arterial pressure from 117 to 106 mmHg (P < 0·01), a decrease in mean pulmonary arterial pressure from 29 to 22 mmHg (P < 0·01), an increase in cardiac index from 4·53 to 4·64 min‐1 m‐2 (NS), an unchanged arterial oxygen tension, and an increase in the calculated oxygen delivery from 834 to 856 ml O2 min‐1 m‐2 (NS).

It was concluded that terbutaline augments right ventricular function: increases right ventricular ejection fraction and decreases right ventricular end‐diastolic volume, and further decreases pulmonary vascular resistance without decreasing arterial oxygen tension, and increases oxygen delivery in patients with chronic pulmonary disease during rest and exercise.
Effects of ischaemic training on force development and fibre‐type composition in human skeletal muscle
Authors: Eiken O. , Sundberg C. J. , Esbjörnsson M. , Nygren A. , Kaijser L.
Published: April 2008

Summary. Force (peak torque) of m. quadriceps femoris was measured during 60 repeated, voluntary dynamic knee extensions in 10 men before and after a 4‐week training regimen of one‐legged cycle exercise. Biopsies for histochemical analysis were obtained from the lateral vastus muscle after the training period. One leg was trained with the blood flow to the leg muscles reduced by local supra‐atmospheric external pressure of 50 mmHg (‘Ischaemic leg, I‐leg’). Employing the same work‐load profile the other leg was trained at normal atmospheric pressure (‘Non‐restricted‐flow leg, N‐leg’). In response to I‐training, Maximum Peak Torqued (MPT; the highest torque produced in any contraction) and Initial Peak Torque (IPT; the average peak torque of the initial 12 contractions) decreased by 8% (P<0.01) and 9% (P<0.001), respectively. Final Peak Torque (FPT; the average peak torque of the final 12 contractions) increased by 13% (P<0.05) after I‐training. No changes in MPT, IPT or FPT occurred following N‐training. After training the proportion of slow‐twitch fibres was higher (P<0.05) and the mean slow‐twitch fibre area was larger (P<0.05) in the I‐than in the N‐trained leg. The results indicate that blood flow‐restricted training, in contrast to non‐restricted‐flow training, decreases maximum voluntary dynamic force, possibly by inducing an increase in the share of the muscle cross‐sectional area consisting of slow‐twitch fibres. That flow‐restricted training improves maintenance of force during short‐term local exercise may reflect ischaemically induced changes in the metabolic characteristics of skeletal muscle.
Reliability of impedance cardiography in measuring central haemodynamics
Authors: Mehlsen J. , Bonde J. , Stadeager C. , Rehling M. , Tangø M. , Trap‐Jensen J.
Published: April 2008

Summary. The purpose of the study described here was to investigate the reliability of impedance cardiography (IC) in measuring cardiac output (CO) and central blood volume. Absolute values and changes in these variables obtained by impedance cardiography and by isotope‐ or thermodilution techniques were compared. The reproducibility of IC within the same day was compared with that of isotope dilution and the reproducibility in IC from day to day was derived. Finally, the effects of the readings of impedance tracings by different observers were quantified. The results are based on 270 measurements in 37 healthy subjects and in 25 unmedicated patients with ischaemic heart disease.

We obtained significant correlations between absolute values y = 0·68x+1·48) and changes (y = 1·00x+0·0003) in CO measured by IC and isotope‐ or thermodilution. IC significantly overestimated absolute values of CO (P <0·001). We found a qualitative but no quantitative correlation between thoracic fluid volume measured by IC and central blood volume measured by isotope dilution.

IC was highly reproducible both when studies were repeated within the same day (SD on differences in CO = 0·36 1 min1 for IC; SD on differences in CO = 0·30 1 min1 for isotope dilution) and on different days (SD on differences in CO = 0·45 1 min1). A low intra‐observer variability was found (SD on differences in CO = 0· 121min1).

We conclude that impedance cardiography is reliable in measuring changes in cardiac output and thus suitable for repeated measurements in studies on the haemodynamic effects of physiological or pharmacological intervention. Impedance cardiography is sufficiently reliable for comparison of absolute values of CO between different groups of patients. We cannot recommend impedance cardiography for quantitative studies of central blood volume.
Local and central sympathetic reflex control of blood flow in skeletal muscle and subcutaneous tissue in normal man
Authors: Andersen E. B. , Boesen F. , Henriksen O.
Published: April 2008

Summary. The effect of age and sex on relative changes in blood flow and vascular resistance in skeletal muscle and subcutaneous tissue during postural changes and during local increase in transmural pressure was studied in 33 healthy subjects.

The intra‐individual variation was studied in five subjects. Blood flow was measured by the local 133Xenon wash‐out method. No relation to age or sex was seen in the centrally elicited sympathetic vasoconstrictor responses in subcutaneous tissue and skeletal muscle and in the locally elicited vasoconstriction in subcutaneous tissue. A small, but statistically significant, correlation to sex and age was found in the local sympathetic vasoconstrictor response in skeletal muscle. The age correlation was caused only by an attenuated response in the young subjects below 40 years of age and may be fortuitous. The intra‐individual variation was acceptably small.

Based on the present results, a reduction in blood flow in skeletal muscle and subcutaneous tissue during centrally or locally elicited sympathetic vasoconstriction of 10% or less should be considered abnormal.

The local 133Xenon wash‐out method is of value in examining patients suspected of dysfunction in the sympathetic part of the autonomic nervous system.