Biomedical subjects

L Kaijser

Publications and source records attributed to L Kaijser.

At least 19 recordsLinked to original sources

PubMed1992

Adenosine induced chest pain--a comparison between intracoronary bolus injection and steady state infusion.

OBJECTIVE: Adenosine may induce chest pain in at least two ways, either by direct stimulation of sensory afferents before actual ischaemia occurs or secondary to ischaemia. The aim was to study if the mechanism of pain induction may depend on the method of adenosine administration. METHODS: Increasing doses of adenosine were given to seven male patients with ischaemic heart disease referred for coronary angiography: first as a bolus intracoronary injection (2.5-50 mumol), second as a 1 ml.min-1 steady state infusion (0.01-20 mumol.min-1) and third as an intravenous steady state infusion (0.076-0.76 mumol.kg-1 x min-1). Pain, rate-pressure product, coronary sinus blood flow, and ECG were monitored. Lactate was analysed in coronary sinus and arterial blood. RESULTS: After intracoronary bolus injection there were no signs of myocardial ischaemia, whereas during intracoronary steady state infusion, and in spite of a lower, but definite, degree of pain, 5/7 patients showed myocardial lactate production and three patients showed ST depression. During the intravenous steady state infusion 6/6 patients showed ST depression. CONCLUSIONS: These findings suggest that when using adenosine for studies on the mechanisms of chest pain in patients with ischaemic heart disease it is preferable to use an intracoronary bolus injection technique rather than a steady state infusion, as the risk of inducing ischaemia with the latter model cannot be ignored.

Adenosine↗

PubMed1992

Correlation between computer-assisted femoral arteriography and physiological tests in hypercholesterolaemic patients: a methodological study with special reference to clinical trials.

The validity of computer-assisted femoral arteriography, for the study of regression/progression of atherosclerosis in follow-up clinical trials, was investigated by comparison with routine physiological estimates of peripheral circulatory function. Thus, in 114 hypercholesterolaemic patients, the results of aorto-femoral arteriography were compared with those of leg segmental blood pressure measurement, oscillometry, digital pulse plethysmography, and bicycle and treadmill exercise tests. In 107 patients, 18 with symptoms of peripheral vascular disease (PVD) and 89 asymptomatic, magnification arteriograms of a 20 cm segment of the right or left superficial femoral artery were obtained. These arteriograms were digitized and the following variables were calculated: arterial lumen volume (corrected for body size), per cent stenosis, and edge roughness. The correlation between arteriographic and physiological variables was investigated with a linear regression model, taking into account the possible interaction with sex, and presence or absence of symptoms of PVD. Lumen volume correlated significantly with all five physiological variables, and per cent stenosis correlated significantly with four of the physiological variables. For the roughness measure, however a significant correlation was found only with plethysmography. By using logistic multiple regression analysis linear functions of physiological variables were constructed to detect ilio-femoral arterial occlusion. The sensitivity/specificity for detection of right-sided, left-sided, and bilateral occlusion was 0.83/0.98, 0.78/0.98, and 0.60/1.00 respectively (N = 108-111). Systolic blood pressure (ankle-arm ratio) was the single variable most closely correlated to the likelihood of arterial occlusions. It is concluded that arterial lumen volume and per cent stenosis, measured for the digitized femoral arteriogram, correlate well with physiological variables, which reflect the state of atherosclerosis both in the femoral arteries and in other arterial beds including the heart, and that routine physiological tests can be used to identify patients with arterial occlusions in the iliac and femoral arteries.

Adult↗

PubMed1992

Myocardial lactate extraction and release at rest and during heavy exercise in healthy men.

The relationship between myocardial lactate extraction and blood lactate concentration and the possibility that simultaneous uptake and release of lactate occur in the normal human heart was investigated by measuring arterial-coronary sinus differences of lactate and of labelled lactate during infusion of 14C lactate in 13 healthy young male volunteers. Measurements were done at rest, during increased cardiac work with unaltered arterial lactate concentration achieved by atrial pacing and during increased cardiac work and increased arterial lactate concentration achieved by supine cycle ergometer exercise. There was on no occasion a significant difference in 14C lactate specific activity between arterial and coronary sinus blood, i.e. no significant admixture of non-labelled lactate occurred in the coronary sinus indicating that on no occasion was there any sign of lactate release. The myocardial extraction of lactate seemed to be a linear function of arterial lactate concentration. During exercise with an arterial lactate concentration of 6 mmol l-1 and above, lactate could have covered approximately 75-100% of the oxidative metabolism. Thus, during short-term heavy work myocardial lactate extraction dominates over other substrates (mainly free fatty acids and glucose) taken up by the heart, and used for oxidation by the heart muscle cells.

Adult↗

PubMed1992

Effects of graded restriction of perfusion on circulation and metabolism in the working leg; quantification of a human ischaemia-model.

An experimental model used with the intention of mimicking the ischaemic condition in patients with arterial obliterative disease was evaluated. The influence of reduced effective perfusion pressure by increased external pressure on leg blood flow and metabolism was determined during exercise in 10 healthy subjects. Catheters were inserted into the right femoral artery and vein and into the left femoral vein. Supine one-legged (n = 5) or two-legged (n = 5) cycle exercise was performed with the subject's legs in a pressure chamber. Zero and three different levels of local supra-atmospheric pressure were applied over the legs: 30, 50 and 60 mmHg. Three submaximal work loads were used: 24, 48 and 72 W/leg. Leg blood flow was measured by the constant-infusion dye-dilution technique. Samples were also drawn from the femoral artery and vein for oxygen saturation and lactate determinations and arterial pressure was recorded. Exercise blood flow decreased progressively with increasing chamber pressure (P less than 0.001). Exposure to 50 mmHg over the working leg led to a mean reduction of blood flow by 16% and venous oxygen saturation by 12 percentage units (P less than 0.05). Lactate release increased with increasing pressure (P less than 0.05). In summary, local application of moderate positive external pressure over the working leg reduces blood flow in a 'dose-dependent' manner, and as a consequence, femoral venous oxygen saturation decreases and lactate release increases. Thus, this method makes it possible to induce graded ischaemia in human skeletal muscle during exercise in a controlled fashion.

Adult↗

PubMed1991

Neurogenic forearm vasodilatation during contralateral isometric exercise is attenuated in diabetes mellitus.

The responses in heart rate, blood pressure and blood flow in the resting forearm during contralateral isometric handgrip were investigated together with the respiratory sinus arrhythmia (measured during standardized breathing frequency and depth), and the heart rate response to a Valsalva manoeuvre in 20 patients with insulin-dependent diabetes and clinical signs of a peripheral neuropathy. The respiratory sinus arrhythmia and the Valsalva ratio were attenuated in the patients compared to age-matched controls, indicating reduced vagal function. Also the responses to handgrip were reduced. The blood flow increase in the resting forearm upon handgrip was correlated with both the respiratory sinus arrhythmia and the Valsalva ratio, supporting neurogenic mediation of the flow response and indicating a reduction in sympathetic as well as vagal function in diabetes autonomic neuropathy.

Adult↗

PubMed1991

Autonomic nervous system function in patients with primary obstructive sleep apnoea syndrome.

Ten patients with obstructive sleep apnoea syndrome cured by uvulopalatopharyngoplasty were compared to nine patients considered as surgical failures, using cardiovascular reflex tests--Valsalva manoeuvre, respiratory sinus arrhythmia, isometric handgrip and head-up tilt. Two patients had signs of moderate vagal dysfunction, but no case of definite autonomic nervous dysfunction was diagnosed. The overall results indicated sympathetic overreactivity, positively correlated to oxygen desaturation indices and remaining after successful treatment. Four patients did not exhibit bradycardia during sleep apnoea. Two of them had decreased respiratory sinus arrhythmia when awake, but two had normal values. This implies a difference in vagal responsiveness between the awake and sleeping states, or that other factors besides vagus function influence the bradycardia response to apnoea. The group mean values were all within normal limits. There was no significant difference between the two groups in any test. Autonomic nervous dysfunction therefore does not seem to contribute to surgical failure, nor to occur with increased incidence among patients with primary obstructive sleep apnoea syndrome.

Adult↗

PubMed1991

Increased insulin-stimulated glucose uptake by exercised human muscles one day after prolonged physical exercise.

We evaluated whether the increased peripheral insulin sensitivity often reported after physical exercise is generalized or limited to the active musculature. Substrate exchange in leg (previously active) and forearm (previously inactive) were measured by catheterization technique basally and during a hyperinsulinaemic euglycaemic clamp (2 mU insulin kg-1 BW min-1) in nine healthy men before and 1 day after 3-h exercise (50% VO2max). One day after exercise basal glucose uptake was unchanged in the leg, while it was decreased in the forearm (-61%, P less than 0.01) compared with the pre-exercise condition. Glucose uptake during hyperinsulinaemia was increased in the leg (+31%, P less than 0.05), but not in the forearm. Basal lactate release by the leg was increased by the exercise, while lactate release by the forearm was decreased, significantly only during the clamp. These results indicate that local and not systemic factors are responsible for the changes in insulin sensitivity observed in the recovery from physical exercise.

Adult↗

PubMed1991

Effects of ischaemic training on force development and fibre-type composition in human skeletal muscle.

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 less than 0.01) and 9% (P less than 0.001), respectively. Final Peak Torque (FPT; the average peak torque of the final 12 contractions) increased by 13% (P less than 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 less than 0.05) and the mean slow-twitch fibre area was larger (P less than 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.

Adult↗

PubMed1991

Effect of coronary bypass surgery on anaerobic myocardial lactate metabolism during pacing-induced angina pectoris.

Myocardial lactate metabolism was studied by coronary sinus catheterization in nine patients before and 8-12 months after coronary bypass surgery. Measurements were performed at rest and during atrial pacing increased to a heart rate which produced strong chest pain. The estimation of myocardial lactate extraction and release was facilitated by a constant rate infusion of 14C lactate and coronary sinus blood flow (CSBF) was measured by thermodilution. Pre-operatively strong chest pain could be elicited in all patients and isotope data indicated a significant myocardial lactate release in all of them, although the net a-cs difference was negative in only half of them. After bypass surgery the maximum tolerable heart rate was increased by 23 beats min-1 and chest pain both at heart rate 110 beats min-1 and at the highest heart rate achieved was reduced or absent in eight of the nine patients. The increase in chest pain during pacing was quantitatively related to the increase in myocardial lactate release, and the correlation between these two variables followed the same course after the operation as it did before. It is concluded that the improvement in chest pain limited cardiac performance after bypass surgery is well correlated with the improvement in myocardial aerobic metabolism.

Aged↗

PubMed1991

Potent vasoconstrictor effects and clearance of endothelin in the human forearm.

The vascular effects of endothelin-1 in humans were investigated by infusion into the brachial artery of healthy volunteers. Endothelin-1 (5-500 pmol min-1) evoked potent and long lasting increase in forearm vascular resistance (FVR) and reduction in venous compliance, suggesting constriction of both resistance and capacitance vessels. The threshold for effect on forearm vascular resistance was at a calculated plasma concentration of 614 pmol 1-1. Endothelin-1 was on a molar basis 10-20 times more potent than noradrenaline as constrictor of both resistance and capacitance vessels. The increase in forearm vascular resistance induced by endothelin-1 lasted more than 30 min and that by noradrenaline less than 3 minutes. The endothelin-1-like immunoreactivity collected in the venous effluent during the infusion was 10-26% of the calculated arterial plasma concentration, indicating local removal of endothelin. After the infusion of endothelin-1 the urine concentration of prostacyclin metabolite increased significantly, indicating release of prostacyclin, whereas the concentration of thromboxane metabolite did not increase. It is concluded that endothelin-1 is a highly potent constrictor of human resistance and capacitance vessels, that it causes release of prostacyclin and that circulating endothelin-1 is efficiently removed by the forearm in vivo.

Adult↗

PubMed1991

Myocardial blood flow and lactate metabolism at rest and during exercise with reduced arterial oxygen content.

The effect of a reduction in arterial oxygen content, equivalent to acute exposure to an altitude of 2300 metres above sea level, on myocardial blood flow and oxygen and lactate exchange was studied by coronary sinus catheterization in 12 healthy men. Measurements were made at rest, during atrial pacing and during submaximal and maximal exercise both breathing air and breathing 15% oxygen (hypoxia). Coronary sinus blood flow was measured by thermodilution and the possibility of a simultaneous uptake and release of lactate by the heart was calculated using intravenous infusion of 14C lactate. At all levels of cardiac power output myocardial oxygen consumption was the same during hypoxia as during air breathing. At rest this was achieved entirely by a more complete extraction of oxygen from the coronary blood, during maximal exercise entirely by a greater coronary sinus blood flow, while at intermediate levels of cardiac power output a combination of these mechanisms prevailed. At rest and during submaximal work myocardial lactate extraction was lower with hypoxia than air breathing suggesting a change in myocardial redox state, while the 14C lactate data suggested no significant lactate release or possibly limited areas with some lactate production. During maximal exercise, however, there was no difference in myocardial lactate net extraction between hypoxia and air breathing, which together with the greater blood flow suggests that the heart has a 'coronary flow reserve' permitting maximal exercise at moderate altitude without anaerobic myocardial metabolism.

Adult↗

PubMed1990

Effect of alcohol on perceived exertion in relation to heart rate and blood lactate.

The purpose of the study was to determine whether the perception of exertion is affected by alcohol during physical performance and whether altered self-rating of exertion is the result of an altered perception per se or of an altered physical capacity to perform work. Ten healthy men participated. Each subject was his own control and received an alcohol dose corresponding to 1 g.kg-1 body mass in 40% solution in the experimental session. The exercise test was performed on a cycle ergometer with an initial intensity of 50 W which was increased stepwise by 50 W at 4-min intervals up to near-maximal. The rating of perceived exertion (RPE) did not differ between alcohol and control sessions. Alcohol induced a significant increase in heart rate during exercise at 50 W (delta x = 8 beats.min-1) and at 100 W (delta x = 10 beats.min-1), while the change at higher intensities was insignificant. The systolic blood pressure and the blood lactate concentration were not significantly changed by alcohol. It is concluded that a moderate dose of alcohol does not alter RPE during physical exercise either per se or secondarily to an altered physical capacity to perform work.

Adult↗

PubMed1990

Nicotine enhances angina pectoris-like chest pain and atrioventricular blockade provoked by intravenous bolus of adenosine in healthy volunteers.

An attempt was made to study possible interaction between neuromodulation by adenosine and nicotine stimulatory effects. Dose-effect curves were made double blind in 7 nonsmoking, nonsnuffing healthy volunteers (25-49 years) before and during exposition to nicotine roughly corresponding to the nicotine of one cigarette, 2 mg ingested from a chewing gum (800 chews during 20 min). Chest pain was estimated by the Borg CR-10 scale. ECG was followed, and respiration was recorded continuously by spirometry. Maximal tolerable dose of adenosine was 12.7 +/- 3.0 mg. Chest pain increased dose dependently to 5.7 +/- 1.7 units. Nicotine increased the pain response by 20 +/- 15%, (p less than 0.02). The total time with atrioventricular (AV) block provoked by adenosine increased with nicotine (7 +/- 12%, p less than 0.03) while increased ventilation provoked by adenosine was unaffected by nicotine. In conclusion, interaction between adenosine and nicotine was demonstrated. Nicotine enhanced both stimulatory (chest pain) and inhibitory actions (AV-block) of adenosine.

Adenosine↗

PubMed1990

Exercise-induced changes in insulin-like growth factors and their low molecular weight binding protein in healthy subjects and patients with growth hormone deficiency.

Serum concentrations of insulin-like growth factors 1 and 2 (IGF-1 and IGF-2), the low molecular weight form of IGF binding protein (IGFBP-1), insulin, C-peptide and GH were determined in six healthy subjects and four patients with GH deficiency during 30 min of moderate physical exercise on the cycle ergometer. The load corresponded to 60% of individual maximal oxygen uptake. IGF-1 and IGF-2 were determined by radioimmunoassays developed with antibodies isolated from immunized hens eggyolk after separation by automated acid gel filtration of serum samples prior to assay. Significant increases in the serum concentrations (mean +/- SEM) of IGF-1 (157 +/- 24 to 196 +/- 29 micrograms l-1, P less than 0.05) and IGF-2 (451 +/- 37 to 678 +/- 85 micrograms l-1, P less than 0.01) were seen in the healthy subjects after 10 min of exercise. The mean percentage increase was 26 +/- 5% for IGF-1 and 50 +/- 11% for IGF-2. No relation to the GH release was found. In GH-deficient patients the mean IGF-2 concentration rose 48 +/- 17% from basal 216 +/- 63 micrograms l-1 to a peak concentration of 324 +/- 115 micrograms l-1 (P less than 0.01) after 30 min, while the 38 +/- 20% rise of IGF-1 from basal 36 +/- 13 micrograms l-1 to a peak concentration of 55 +/- 27 micrograms l-1 was not significant. The serum IGFBP-1 concentration did not change during exercise, while insulin and C-peptide concentrations, as well as blood glucose, decreased in both healthy subjects and GH-deficient patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

Discrepancy between estimated energy intake and requirement in female dancers.

Dietary intake of energy, protein, fat and carbohydrates in female dance students compared to female music students was estimated by a dietary history method. Energy requirement was estimated from body weight and physical activity both by a standard formula and from the measured work intensity during dance training. Meal patterns showed significant differences in four types of meals on week-days and in one type on weekends. The intake of protein, fat and carbohydrates in absolute amounts and the percentage of energy derived from protein were not significantly different between the two groups. The fraction of energy derived from carbohydrates was higher and that from fat was lower in the dancers than in the musicians. Energy intake was of similar magnitude for the dancers and the musicians (8.3 +/- 1.9 MJ vs. 8.3 +/- 1.7 MJ), while the estimated energy requirement was greater for the dancers (10.3 +/- 0.7 MJ vs. 8.9 +/- 0.4 MJ). The reason for the apparent discrepancy between energy intake and energy requirement of approximately 2 MJ in the dancers is not obvious. The energy intake may have been underestimated. Alternatively, the energy requirement may have been overestimated. The resting metabolic rate may have been depressed by years of low energy intake. In addition, as suggested by some authors, training as such may lower the resting metabolic rate as well as the diet-induced thermogenesis.

Adult↗

PubMed1990

Coronary circulation in acute hypoxia.

Healthy young men were subjected to different degrees of hypoxia at rest and during increased levels of cardiac work induced by atrial pacing and physical exercise at submaximal and maximal loads. Coronary sinus (cs) blood flow was measured by thermodilution and a-cs differences of O2 and lactate were obtained. At low cardiac power output (rest, pacing) the reduction in arterial oxygen content was compensated for mainly by a more complete myocardial oxygen extraction producing lowered cs O2 saturation and tension, while at higher cardiac power (exercise) the compensatory mechanism was entirely an increased coronary blood flow. It was possible to compensate fully for a reduction in arterial O2 saturation of 9% even during maximal physical exercise. With a reduction in arterial oxygen content of more than 20-25% the flow increase was sufficient to supply the heart with enough O2 during submaximal (heart rate 157 beats min-1) but not maximal exercise, in which case anaerobic glycolysis contributed significantly to the myocardial energy metabolism. It is concluded that the normal heart has a 'coronary flow reserve' of about 33% above the flow prevailing during maximal physical exercise under air breathing.

Adaptation, Physiological↗

PubMed1990

Neuropeptide Y is released together with noradrenaline from the human heart during exercise and hypoxia.

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.

Adult↗

PubMed1990

Lung function in patients with prior poliomyelitis.

Lung volumes and spirometric flows, maximal respiratory pressures, lung diffusion capacity and blood gases were evaluated in 20 patients with prior poliomyelitis and compared with data from an age- and sex-matched control group. In the polio patients, static lung volumes and pulmonary flow capacity were significantly reduced to approximately 65% of the values of the control group. However, expiratory and inspiratory flows were normal in relation to lung volumes, while maximal respiratory pressures were significantly reduced in the polio patients. Static lung volumes and forced flows were correlated with the maximal respiratory pressures both in the polio patients and in the controls. However, when the muscle force in the polio patients decreased below a certain level, it became more important as a determinant of lung-flow capacity. The polio patients had a significantly increased PCO2 but a normal oxygen saturation and PCO2 was inversely correlated with the maximal respiratory pressures in the patients but not in the controls. The lung diffusion capacity was reduced in the polio patients compared to the controls, but less markedly than vital and total lung capacity. The findings indicate a restrictive respiratory dysfunction and alveolar hypoventilation most probably due to weakness of the respiratory muscles.

Adult↗