Biomedical subjects

A Bengtsson

Publications and source records attributed to A Bengtsson.

At least 91 records · Page 5Linked to original sources

PubMed1996

Factor V:Q506 mutation and anticardiolipin antibodies in systemic lupus erythematosus.

Inherited resistance to activated protein C (APC resistance) is an important risk factor of venous thrombosis. It is caused by a point mutation in the gene coding for coagulation factor V, called FV:Q506. Arterio-venous thrombosis is a common and serious medical problem in patients with systemic lupus erythematosus (SLE). We studied the prevalence of the factor V mutation associated with APC resistance and IgG anticardiolipin antibodies (aCLs) in an epidemiological cohort of 78 Swedish SLE patients, to determine their roles as risk factors for thrombosis. In addition, a detailed evaluation of the clinical manifestations in these patients was performed. Totally, 19 (24%) of the 78 SLE patients had thrombosis, 11 (14%) had venous thrombosis and 8 (10%) had a cerebral infarction caused by occlusion of cerebral vessels. Twenty-six (33%) SLE patients were aCL positive and 8 (10%) were heterozygous for the factor V mutation. Only one of the patients with venous thrombosis and one of the patients with cerebral thrombosis had the FV:Q506 mutation, whereas 3 patients with venous thrombosis and 5 patients with cerebral infarction were aCL positive. Eleven of 19 patients with heart valve disease were aCL positive, a statistically significant association (P = 0.01). In conclusion, we found no statistically significant association between venous thrombosis and FV:Q506 mutation or venous thrombosis and aCL positivity. There was, however, an association between heart valve disease and aCL positivity.

Adolescent↗

PubMed1996

Increased release of tumor necrosis factor-alpha and interleukin-6 in women with the syndrome of hemolysis, elevated liver enzymes, and low platelet count.

BACKGROUND: Complement is activated in preeclampsia and complement products are known to activate macrophages. The aim of this study was to determine whether the macrophage derived cytokines, interleukin-1 beta, interleukin-6 and tumor necrosis factor-alpha, are released in patients with a form of severe preeclampsia characterized by the syndrome of hemolysis, elevated liver enzymes, and low platelet count (HELLP syndrome). METHODS: Complement activation and plasma levels of cytokines were studied in 11 women with HELLP syndrome and in 11 controls with uncomplicated pregnancies. To further evaluate the connection between complement activation and cytokine release an in vitro study on heparinized whole blood incubated with recombinant C5a was performed. RESULTS: In the HELLP group, complement anaphylatoxin C5a was increased in plasma at delivery (p < 0.01) and one day after delivery (p < 0.05), terminal C5b-9 complement complex was elevated in plasma at delivery (p < 0.001) and one day after (p < 0.01), plasma levels of interleukin-6 were increased one day after delivery (p < 0.01), and plasma concentrations of tumor necrosis factor-alpha were elevated at delivery (p < 0.01), compared with corresponding levels in controls. All parameters normalized within one week. Interleukin-I beta did not differ between the groups. In vitro, recombinant C5a incubated in whole blood gave a dose-dependent release of interleukin-6. No increased release of interleukin-1 or tumor necrosis factor-alpha was seen after incubation. CONCLUSIONS: Since cytokine release occurs in severe preeclampsia, inflammatory mechanisms may participate in the pathophysiology of severe preeclampsia.

Adult↗

PubMed1996

Evaluation of tissue trauma after laparoscopic and abdominal hysterectomy: measurements of neutrophil activation and release of interleukin-6, cortisol, and C-reactive protein.

BACKGROUND: Trauma and major surgery stimulate a cascade of events that mediate the inflammatory response. The aim of our study was to determine whether or not hysterectomy leads to release of cytokines, cortisol, and C-reactive protein (CRP), activation of neutrophils, and activation of the complement cascade. A further aim was to compare laparoscopic and abdominal hysterectomy with regard to the same parameters. STUDY DESIGN: Twenty-four consecutive patients were randomized to either abdominal (n = 12) or laparoscopic hysterectomy (n = 12). Blood samples were drawn preoperatively, intraoperatively, and then at one minute, 24 hours, and seven days postoperatively. Interleukin-6 (IL-6) levels were used to evaluate cytokine release, cortisol and CRP to evaluate the inflammatory response, and polymorphonuclear (PMN) elastase to detect neutrophil activation. To evaluate complement activation, the terminal C5b-9 complement complex (TCC) was determined. RESULTS: Interleukin-6 concentrations were significantly elevated one minute and 24 hours postoperatively in both groups. Independent of the surgical technique or operative time, the highest IL-6 concentration was reached four hours after beginning the operation. Cortisol levels were significantly elevated during and after the operation in both groups. C-reactive peptide levels were significantly elevated in both groups 24 hours and seven days after the operation. Polymorphonuclear elastase was elevated 24 hours postoperatively in both groups. There were no signs of complement activation during the operative period or postoperatively in either patient group. CONCLUSIONS: Our results indicate serious tissue trauma during both laparoscopic and abdominal hysterectomy. The extent of surgical trauma did not differ between the two operative methods.

C-Reactive Protein↗

PubMed1995

Why does clozapine stimulate the motor activity of reserpine-pretreated rats when combined with a dopamine D1 receptor agonist?

The aim of the present experiments was to investigate the locomotor stimulant effects of the atypical antipsychotic agent, clozapine, in rats depleted of their dopamine by reserpine and alpha-methyl-p-tyrosine pretreatment. Clozapine itself induced a slight but never significant stimulation of locomotor activity which was enhanced by the addition of the selective dopamine D1 receptor agonist, SKF38393 (2,3,4,5-tetrahydro-7,8-dihydroxy-1-phenyl-1H-3- benzazepine), but not by the selective dopamine D2 receptor agonist, quinpirole. The stimulation produced by clozapine plus SKF38393 was blocked by the selective dopamine D1 receptor antagonist, SCH23390 (7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5- tetrahydro-1H-3-benzapine hydrochloride), while the selective dopamine D2 receptor antagonist, haloperidol, was ineffective. A combination of SCH23390 and haloperidol blocked the clozapine plus SKF38393-induced locomotion. Unlike clozapine, neither the selective 5-HT2 receptor antagonist, ritanserin, nor the dopamine D2 receptor antagonists, haloperidol and remoxipride, caused locomotor activation when given alone or in combination with SKF38393. The indirectly acting sympathomimetic amine, d-amphetamine, was inactive in the monoamine-depleted rats, indicating that no dopamine was available for release by d-amphetamine. The muscarinic receptor antagonist, scopolamine, alone did not alter locomotion, but produced marked stimulation when combined with SKF38393 but not with quinpirole. This stimulation was not affected by haloperidol. However, the scopolamine plus SKF38393-induced stimulation was partially blocked by SCH23390 or by a combination of haloperidol and SCH23390. The data indicate that clozapine, in rats depleted of their dopamine stores, exhibits properties consistent with those of a dopamine receptor agonist.(ABSTRACT TRUNCATED AT 250 WORDS)

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

PubMed1995

Not only Th2 cells but also Th1 and Th0 cells express CD30 after activation.

To investigate whether the CD30 molecule, expressed only by a minority of T and B cells, defines a subtype of T helper cells, Pityrosporum orbiculare-specific CD4+ T cell clones were assessed for CD30 protein and gene expression. The clones were defined as Th1, Th0, and Th2 according to their cytokine mRNA profile detected by reverse transcription PCR (RT-PCR). The kinetics of CD30 expression after OKT3 (anti-CD3) stimulation was analyzed by flow cytometry, immunocytochemistry, and RT-PCR. OKT3 activation induced a high expression of CD30 in cells of both Th1 and Th0 as well as Th2 type after 1-3 days. A difference between the clones was noted in that the Th2 clones remained highly positive in CD30 expression, whereas expression in the other clones started to decline from day 3. These data indicate that CD30 is expressed in activated CD4+ T cells of all three subtypes, and that the expression is sustained in Th2 cells.

Base Sequence↗

PubMed1995

Time course of bromocriptine induced excitation in the rat: behavioural and biochemical studies.

The aim of the present study was to further investigate the behavioural and biochemical pharmacology of the directly acting dopamine (DA) receptor agonist bromocriptine (BRC). BRC produced an initial depression of locomotion followed after about an hour by a weak but significant locomotor stimulation. The stimulation was potentiated by concomitant administration of the D1 agonist SKF38393. Ex vivo biochemical determinations indicated that reductions in dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) levels occurred in the striatum after BRC injection without a significant change in DA levels, indicating a reduced DA turnover. An increase in 5-hydroxytryptamine (5HT) and 5-hydroxyindoleacetic acid (5HIAA) levels occurred in the striatum leading to a significant increase in turnover (i.e. ratio of 5HIAA to 5HT). Noradrenaline concentrations increased in the striatum. In the cortex, sharp falls in HVA and DOPAC levels without a corresponding change in DA were observed. While there was no significant change in noradrenaline levels in this brain region, an increase in 5HIAA, but not in 5HT, levels occurred. These changes indicate an increase in 5HT turnover (ratio of 5HIAA to 5HT). In vivo dialysis indicated that extracellular levels of DA, DOPAC and HVA in the striata of freely moving rats were sharply reduced for at least 6 h after injection. In vitro binding studies showed that BRC exhibited high (Ki values in low nanomolar range) affinities for DA D2A, D2B, D3, alpha 1 and alpha 2 adrenergic receptors together with unexpectedly high affinity (about 1 nM) for 5HT1A receptors. The data indicate that the initial behavioural depression and later locomotor stimulation induced by BRC are accompanied by a sharp monophasic fall in striatal extracellular DA levels as indicated by dialysis studies. Since the behavioural stimulation was augmented by concomitant D1 receptor stimulation, the data suggest that the reduced DA turnover is influencing the amount of DA available to stimulate postsynaptic D1 receptors. However, the biochemical studies indicated that BRC has a high affinity for 5HT1A receptors and affects the turnover of 5HT in the brain. Thus, the behavioural effects of BRC may depend not only on effects on the DA system but also on 5HT systems.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

PubMed1995

Effects of ephedrine on oxygen consumption and cardiac output.

Bolus doses of ephedrine are often used by anaesthesiologists for intraoperative hypotension. This randomized single-blind cross-over study was designed to simultaneously evaluate circulatory, respiratory and metabolic effects of intravenously given ephedrine in 12 healthy male volunteers. Oxygen uptake and carbon dioxide excretion were measured with indirect calorimetry and non-invasive transthoracic electrical bioimpedance was used for cardiac output measurements. The maximum effect on most variables was reached at 4-5 min. At 5 min after the administration of ephedrine 0.1 mg per kilogram body weight, there were significant increases in cardiac index, systolic and mean arterial blood pressure, expired minute volume, oxygen uptake and carbon dioxide excretion rates. There were no significant changes in the quotient between oxygen uptake rate and cardiac index, VO2/CI during the 30 min study period. The O2 saturation was not altered. The present study indicates that ephedrine increases oxygen demand and supply in a similar magnitude.

Adrenergic Agents↗

PubMed1995

Release of inflammatory mediators in association with collection of wound drainage blood during orthopaedic surgery.

Ten patients undergoing hip replacement surgery were studied regarding activation of complement and leukocytes in association with collection of wound drainage blood. The blood was collected postoperatively but not reinfused due to the possible risks with reinfusion of blood containing inflammatory mediators. Blood samples for analysis of complement activation (TCC), leukocyte activation (PMN elastase) and cytokines (Interleukin-6) were drawn preoperatively from the patients. Blood samples were also drawn intraoperatively from the wound. Samples were also drawn from the collected wound drainage blood, before and after blood was passed through a microporous filter. There were elevated concentrations of TCC, PMN elastase and IL-6 in the collected wound drainage blood before and after the filter. The filtration did not significantly reduce the concentrations of these factors. In the wound blood the concentrations were higher compared to those found in the systemic blood preoperatively, but lower compared to concentrations found in the collected drainage blood. The study demonstrates that the collection of wound drainage whole blood is associated with activation of complement, release of PMN elastase and cytokines.

Aged↗

PubMed1995

Pain analysis in patients with fibromyalgia. Effects of intravenous morphine, lidocaine, and ketamine.

Pain intensity, muscle strength, static muscle endurance, pressure pain threshold, and pain tolerance at tender points and control points were assessed in 31 patients with fibromyalgia (FM), before and after intravenous administration of morphine (9 patients), lidocaine (11 patients), and ketamine (11 patients). The three different studies were double-blind and placebo-controlled. The patients were classified as placebo-responders, responders (decrease in pain intensity by > 50%) and non-responders. The morphine test did not show any significant changes. The lidocaine test showed a pain decrease during and after the infusion. The ketamine test showed a significant reduction in pain intensity during and after the test period. Tenderness at tender points decreased and endurance increased significantly, while muscle strength remained unchanged. The present results support the hypothesis that the NMDA receptors are involved in pain mechanisms in fibromyalgia. These findings also suggest that central sensitization is present in FM and that tender points represent secondary hyperalgesia.

Adult↗

PubMed1995

Release of cytokines, polymorphonuclear elastase and terminal C5b-9 complement complex by infusion of wound drainage blood.

25 patients undergoing total hip replacement surgery were studied in an investigation of release of cytokines (interleukin-1 beta, IL-1 beta; interleukin-6, IL-6; interleukin-8, IL-8; and tumor necrosis factor-alpha, TNF-alpha), PMN elastase and terminal C5b-9 complement complexes (TCC) at the time of collection and transfusion of autologous blood. 15 patients received wound blood that was washed and centrifuged before being transfused as an erythrocyte suspension. In this blood there were no elevations in the concentrations of cytokines, TNF-alpha, PMN elastase or TCC, and there was no increase in these variables in plasma after transfusion of wound blood. 10 patients received postoperatively-collected drainage blood. There were high amounts of cytokines, PMN elastase and TCC in this blood, and filtration of the collected drainage blood did not reduce the concentrations of these factors, except those of TCC. When the collected drainage blood was infused, elevated plasma concentrations of IL-6, IL-8 and PMN elastase were observed 1 and 60 minutes after completing the transfusion. No differences regarding blood pressure, oxygen saturation (SpO2), and hemoglobin concentration between the groups were recorded.

Aged↗

PubMed1994

Complement system activation during orthotopic liver transplantation in man. Indications of peroperative complement system activation in the gut.

Sixteen patients with acute and chronic liver disease undergoing OLT were studied regarding the role of the liver and the gut in complement activation. Also, the relation between complement activation and clinical manifestations during the liver transplantation reperfusion period was investigated. Blood samples for measurement of complement anaphylatoxin C3a (C3a), complement anaphylatoxin C5a (C5a), and terminal C5b-9 complement complex (TCC) were taken simultaneously from the central venous catheter and the radial arterial line before starting the operative procedure, 1 min before declamping, and 1-2 min, 5 min, 30 min and 6-12 hr after declamping. Simultaneous blood sampling from the radial arterial line, central venous catheter, portal vein, and hepatic vein was performed 1-2 min and 5 min after completed unclamping. Elevated plasma levels of C3a and TCC were found upon reperfusion, while C5a levels remained unchanged throughout the operation compared with the preoperative levels. The levels of C3a in the portal vein were higher compared with the levels in the simultaneously obtained samples from the radial artery. The results indicate complement cascade activation located to the gut during the reperfusion phase of OLT. Seventy-five percent of the patient studied suffered from the postreperfusion syndrome, indicated by profound hypotension upon reperfusion of the transplanted liver. There was a significant correlation between high concentration of C3a anaphylatoxin and development of profound hypotension.

Adult↗

PubMed1994

Increased antiretroviral antibody reactivity in sera from a defined population of patients with systemic lupus erythematosus. Correlation with autoantibodies and clinical manifestations.

OBJECTIVE: The implied role of retroviruses in the pathogenesis of murine systemic lupus erythematosus (SLE) led us to study antiretroviral antibodies in a population-based SLE cohort. METHODS: Immunoassays using whole virus and synthetic peptides were performed on sera from 72 patients with SLE and 88 control subjects. RESULTS: Reactions with whole baboon endogenous virus occurred more frequently in patients with SLE, and correlated with the presence of anti-RNP and anti-Sm. Some retroviral env and gag peptides, several of which were similar to U1 small nuclear RNP, reacted more strongly in patients with SLE, and their presence was correlated with discoid rash, hematologic disorder, and other symptoms. CONCLUSION: These results provide circumstantial evidence for involvement of retroviruses in the pathogenesis of human SLE; further studies should be carried out using other techniques for measurement of retroviral expression.

Adult↗

PubMed1994

Development of tolerance to 8-OH-DPAT induced blockade of acquisition of a passive avoidance response.

We examined the effects of manipulating 5-HT1A receptors on the performance of a passive avoidance task in rats. Firstly, we studied the effect of racemic 8-OH-DPAT and compared it to the pure enantiomers (subcutaneous injection, s.c.). Secondly, we investigated the effect (s.c.) of the selective 5-HT1A receptor antagonist (S)-UH-301 [(S)-5-fluoro-8-hydroxy-2-(dipropylamino)tetralin] both alone and on 8-OH-DPAT-induced disruption of acquisition. Thirdly, we examined whether tolerance occurs to the effects of 8-OH-DPAT on passive avoidance acquisition. Finally, we examined the effects (s.c.) of the selective NMDA receptor antagonist dizocilpine, (+)-MK-801[(5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo(a,d)cyclohe pten-5, 10-imine], on this tolerance development. Different doses of racemic 8-OH-DPAT were injected 10 min before rats were exposed to the acquisition phase of a step through passive avoidance response. When tested for retention 24 h later, 8-OH-DPAT-pretreated rats failed to exhibit any avoidance. R(+) and S(-)-8-OH-DPAT were also active with the R(+)-isomer being more active than the S(-)-isomer. The 5-HT1A antagonist (S)-UH-301 [(S)-5-fluoro-8-hydroxy-2-(dipropylamino)tetralin] was without effect on avoidance performance but antagonized the effect of 8-OH-DPAT. In a further experiment, rats were pretreated with racemic 8-OH-DPAT (0.3 mg/kg). Twenty four hours later, they received a challenge dose of 8-OH-DPAT and exposed to the acquisition phase of the avoidance response. When tested 24 hr later for retention, 8-OH-DPAT challenged rats failed to show any indication of an avoidance response.(ABSTRACT TRUNCATED AT 250 WORDS)

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed1994

Dopamine receptor antagonists block amphetamine and phencyclidine-induced motor stimulation in rats.

d-Amphetamine (DEX) and phencyclidine (PCP) increased motor activity in rats as measured in automated activity cages. Analysis of the stimulation indicated that both drugs increased horizontal activity (total activity), locomotion, and peripheral activity. However, DEX increased while PCP decreased the incidence of rearing. The ability of different drugs to antagonise DEX- and PCP-induced increases in total activity (called stimulation) was measured. Dopamine (DA) D1 receptor antagonists (SCH23390, NNC-01-0112) were 7-8 times more potent in blocking DEX than PCP. DA D2 receptor antagonists (raclopride, remoxipride, haloperidol) were only 1-2 times more potent against DEX-induced stimulation. Nonselective DA receptor antagonists were also tested. Chlorpromazine was more potent against DEX than against PCP. Buspirone and sertindole were slightly more potent in blocking PCP than DEX. Ritanserin (5-HT2 receptor antagonist) was inactive against both stimulants. 8-OH-DPAT (5-HT1A receptor agonist) potentiated the stimulant effects of DEX and PCP. Prazosin (alpha 1-adrenergic receptor antagonist) partially blocked both DEX and PCP. Most drugs tested depressed spontaneous motor activity. Remoxipride and sertindole, however, caused very little depression even at doses several times higher than those needed to block DEX or PCP. The data show clear pharmacological differences between DEX- and PCP-induced stimulation.

Animals↗

PubMed1994

Allergenic cross-reactivity among peach, apricot, plum, and cherry in patients with oral allergy syndrome: an in vivo and in vitro study.

BACKGROUND: Oral allergy syndrome in response to fruits and vegetables frequently occurs as clusters of hypersensitivity to members of the same botanical family, for which the immunologic basis lies in a number of common allergens, most of them still unidentified. OBJECTIVE: This study was designed to assess the in vivo and in vitro cross-reactivity between fruits of the Prunoideae subfamily (i.e., peach, cherry, apricot, and plum) and to identify their major allergens and the cross-reactivity of the peach extract with grass and birch pollen. METHODS: The in vivo study was conducted by skin prick tests and open food challenges with fresh fruits in 23 patients with oral allergy syndrome for peach and positive skin prick test and RAST results for the other Prunoideae. In vitro sodium dodecylsulfate-polyacrylamide gel electrophoresis was followed by immunoblotting and immunoblotting-inhibition. RESULTS: A 13 kd component was identified as the only major allergen common to all the Prunoideae, the other major allergens were found at 14 kd in peach and at 30 kd in cherry. Immunoblotting inhibition showed wide cross-reactivity within the Prunoideae, whereas grass and birch pollen partially inhibited the peach blotting. CONCLUSIONS: Clinical cross-reactivity to Prunoideae is essentially due to a common 13 kd IgE-binding component, which seems to be the most important major allergen of this subfamily, not shared with grass and birch pollen.

Allergens↗

PubMed1994

Isolated hyperthermic liver perfusion with chemotherapy for liver malignancy.

In an open study of unresectable liver tumours, isolated regional perfusion with hyperthermia and cytotoxic drugs has been tested in 29 patients. Four patients had primary hepatocellular cancer, 10 patients had metastases from malignant melanoma, remaining from breast cancer, colorectal cancer, midgut carcinoids and miscellaneous primaries. At laparotomy the proper hepatic artery and portal vein were canulated and connected to a pump oxygenator. The inferior vena cava was canulated with a triple lumen catheter (Perfufix) allowing for porto-caval shunting, drainage of lower body and renal veins to the heart and separate drainage of liver veins to the pump oxygenator. Liver perfusion was performed with a mean flow of 900 ml per min. Melphalan and cis-platinum 0.5 mg/kg body-weight were added to the perfusate for 1 h after liver temperature reached 40 degrees C. Four patients died within 30 days of perfusion due to multiple organ failure. These patients had more than 50% of liver volume occupied by cancer. All surviving patients developed reversible hepato- and renal toxicity. Partial tumour regression was registered in 20% of the patients. Five patients have survived more than three years. Hyperthermic liver perfusion is feasible but in patients with massive liver tumour, there is a significant risk of developing multiple organ failure.

Adult↗

PubMed1994

Formation of cytokines by retransfusion of shed whole blood.

We have studied, in 10 patients undergoing hip replacement surgery, the release of cytokines (tumour necrosis factor-alpha (TNF-alpha), interleukin-1 alpha (IL-alpha), interleukin-1 beta (IL-1 beta), interleukin-4 (IL-4), interleukin-6 (IL-6) and interleukin-8 (IL-8)) in association with retransfusion of autologous shed blood. The patients were reinfused with whole blood collected after operation. The median volume returned to the patients was 300 ml whole blood (25-75% range = 300-425 ml). Before reinfusion, blood was filtered. Plasma concentrations of IL-6 increased 1 and 60 min after retransfusion (P < 0.05). The plasma concentrations of TNF-alpha, IL-1 alpha, IL-1 beta, IL-4 and IL-8 did not change significantly after retransfusion of shed wound blood. However, there were increased concentrations of IL-1 alpha, IL-1 beta, IL-6 and IL-8 in the collected blood (P < 0.001). The filtration procedure did not reduce significantly the concentrations of these factors. This study shows that whole blood collected from a surgical wound contains large concentrations of cytokines. Filtration of the shed wound blood did not reduce significantly these levels and retransfusion caused increased plasma concentrations of IL-6.

Aged↗

PubMed1994

Effects of hyperventilation on the inspiratory to end-tidal oxygen difference.

We assessed the inspiratory to end-tidal oxygen difference (PIO2-PE'O2) during voluntary hyperventilation in 10 healthy male volunteers. The oxygen difference was measured with a fast-response paramagnetic differential oxygen sensor. As simultaneous changes in metabolism and cardiac output also influence (PIO2-PE'O2), oxygen uptake was measured with indirect calorimetry and non-invasive transthoracic electrical bioimpedance was used for measurement of cardiac output. After a rest period, subjects were instructed to double their minute ventilation volume (VE) and after 5 min triple their resting VE for another 5 min. (PIO2-PE'O2) decreased from a zero value of 6.4 kPa to 3.9 kPa at 5 min (P < 0.01) and 2.9 kPa at 10 min (P < 0.01). At 15 min (i.e. 5 min after the end of hyperventilation) there was an increase in (PIO2-PE'O2) to 8.3 kPa (P < 0.05). Regression analysis between (PIO2-PE'O2) (kPa) and VE (litre m-2 min-1) gave the formula: (PIO2-PE'O2) = 1/(0.059 + 0.034 VE), r = -0.92, n = 158. Oxygen uptake and cardiac output did not change significantly during hyperventilation, but decreased in the post-hyperventilation period. An oxygen difference of more than 8 kPa was associated with significant arterial desaturation.

Adult↗