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Biomedical subjects

L Kaijser

Publications and source records attributed to L Kaijser.

At least 91 records · Page 5Linked to original sources
PubMed1987

Muscle fiber characteristics in female dancers during an active and an inactive period.

Muscle biopsies were taken from female dancers, aged 24 +/- 2 years, first during an active period and then after 32 weeks of detraining. During the active period, the percentage of type I fibers was 63% +/- 12%, and of the subgroups IIA, IIB, and IIC, 26% +/- 9%, 8% +/- 7%, and 3% +/- 3%, respectively. There was no significant change due to detraining either in the proportion of type I fibers or in the type II subgroups. During the active period, the cross-sectional area of the type I fibers was 3798 +/- 586 micron 2. The areas of the subgroups IIA, IIB, and IIC were 3394 +/- 858, 2497 +/- 530, and 3296 +/- 638 micron 2, respectively. After the detraining period, the area of the type I fibers had increased significantly (P less than 0.05). The areas of the types IIA, IIB, and IIC tended to be increased although not significantly. It is suggested that the comparatively high percentage of type I fibers, which was found in the active dancers, is the result of selection rather than of training, while the small fiber areas seem to be due to training.

Adult↗
PubMed1987

Myocardial enzyme activities in patients with mitral regurgitation or mitral stenosis.

To determine the adaption of myocardial metabolism in mitral regurgitation and mitral stenosis, human papillary muscles obtained during open heart surgery were analysed to measure selective enzyme activities in energy metabolism. All enzyme activities were expressed per unit dry weight muscle, per unit alkali soluble protein, and per unit total creatine and the different results compared. The activities of enzymes concerned with mitochondrial energy production and energy transfer (namely, citrate synthase and mitochondrial creatine kinase) tended to be higher in papillary muscles from hearts with mitral regurgitation than in those with mitral stenosis. The activities of enzymes concerned with cytoplasmic energy production (creatine kinase MM, lactate dehydrogenase, and phosphofructokinase) did not show statistically significant differences between mitral regurgitation and mitral stenosis. The ratio of creatine kinase MB activity to total creatine content showed the greatest difference when papillary muscles from patients with mitral regurgitation and mitral stenosis were compared (31% higher in mitral regurgitation; p less than 0.001). The specific function of creatine kinase MB, which is located in cytoplasm, is not well defined. Creatine kinase MB activity increases with extreme endurance training of human skeletal muscle. Thus the higher creatine kinase MB activity in papillary muscle of mitral regurgitation may represent an adaptation to increased physical demand.

Adult↗
PubMed1987

Adenine nucleotide degradation in the human myocardium during cardioplegia.

The tissue content of adenine nucleotides and their metabolites, inosine monophosphate, adenosine, hypoxanthine, and uric acid, were determined in biopsy specimens from the left ventricle of six patients during cardioplegia for open heart surgery. Biopsy specimens were collected immediately after the induction and at the end of cardioplegia (51-82 min) and were analysed by high performance liquid chromatography. After the induction of cardioplegia (cold potassium enriched solution) the left coronary artery was continuously perfused with cold (10 degrees C), potassium enriched, diluted blood. The adenosine triphosphate concentration decreased from 13 to 8 mmol.kg-1 dry muscle (p less than 0.01) during cardioplegia. Adenosine diphosphate and adenosine monophosphate concentrations were 6 and 3 mmol.kg-1 dry muscle respectively and remained unaffected. The adenosine concentration (0.3 mmol.kg-1 dry muscle) was three times higher than that of inosine monophosphate. Inosine concentrations increased from 0.8 to 2.7 mmol.kg-1 dry muscle (p less than 0.01) in parallel with the increase in hypoxanthine from 0.1 to 0.4 mmol.kg-1 dry muscle (p less than 0.01). The total adenine nucleotide pool decreased by 5 mmol.kg-1 dry muscle (p less than 0.01), whereas the corresponding increase in nucleotides and bases only was 2 mmol.kg-1 dry muscle. In conclusion, the adenosine triphosphate content and the adenine nucleotide pool were appreciably reduced during continuous cold blood cardioplegia as used in the present study. The tissue content of adenosine and further metabolites was considerably increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine Nucleotides↗
PubMed1987

ATP breakdown products in human skeletal muscle during prolonged exercise to exhaustion.

To study changes in muscle energy state during prolonged exercise, especially in relation to fatigue, muscle biopsies were obtained from seven healthy males working until exhaustion on a cycle ergometer at 68% (63-74%) of their maximal oxygen uptake. Biopsies were taken at rest, after 15 and 45 min of exercise and at exhaustion, and analysed for ATP, ADP, AMP, inosine monophosphate (IMP) and hypoxanthine content by high performance liquid chromatography (HPLC), and for creatine phosphate (CP), lactate and glycogen by enzymatic fluorometric techniques. Glycogen content at exhaustion was approximately 30% of the pre-exercise level. The CP content decreased steeply during the first 15 min of exercise (P less than 0.01) and continued to decrease during the rest of the exercise period (P less than 0.05). Pronounced increases in contents of IMP (64% P less than 0.001) and hypoxanthine (69%, P less than 0.05) were found when exhaustion was approaching. Furthermore, energy charge [EC; (ATP + 0.5 ADP)/(ATP + ADP + AMP)] was decreased at exhaustion (P less than 0.05). The increases in IMP and hypoxanthine which occurred when exhaustion was approaching during prolonged submaximal exercise together with the decrease in EC during this phase of exercise suggest a failure of the exercising skeletal muscle to regenerate ATP at exhaustion.

Adenosine Diphosphate↗
PubMed1987

Myocardial energy metabolism in the induction phase of cardioplegia in relation to myocardial temperature during open heart surgery.

Changes in myocardial high energy phosphate and lactate concentrations during initiation of cardioplegia for open heart surgery were studied in 21 patients and related to their individual myocardial temperatures. Left ventricular myocardial biopsies were taken 10 min post aortic cross-clamping and were analysed for ATP, creatine phosphate (CP), creatine (C) and lactate. The patients were divided into three groups according to the achieved myocardial temperature: 6-10 degrees C, 11-15 degrees C and 16-24 degrees C. The results indicated that optimal myocardial protection during the induction phase of the cardioplegia was obtained in the 11-15 degrees C group in which the highest ATP concentration and simultaneously lowest lactate concentration was maintained.

Adenosine Triphosphate↗
PubMed1987

Autonomic cardiovascular responses in distal myopathy (Welander).

Autonomically mediated cardiovascular responses were evaluated in 9 patients with Welander distal myopathy and compared to data from an age- and sex-matched control group. The myopathy patients had a normal respiratory sinus arrhythmia and a normal heart rate response to the Valsalva menoeuvre, indicating a normal vagal function. They had a normal initial heart rate response to the orthostatic position, indicating a normal function of the sympathetic nerves. The main difference between the groups was found in the orthostatic position. The myopathy patients reacted with a greater increase in systolic blood pressure and a smaller heart rate increase than the controls. This suggests an altered peripheral vasomotor function, possibly with a more predominant activation of alfa than beta adrenergic receptors leading to vasoconstriction. In addition, a low forearm blood flow at rest and a les pronounced blood flow increase during the isometric handgrip were found in the myopathy patients. This finding could also be explained by proneness to vasoconstriction. It is concluded that patients with Welander distal myopathy have no signs of dysfunction of the peripheral autonomic nerves.

Adult↗
PubMed1987

Substrate utilization and enzymes in skeletal muscle of extremely endurance-trained men.

Substrate utilization during exercise at 65% of maximal O2 uptake (VO2 max) and biochemical characteristics of vastus lateralis were compared between five endurance-trained (T) and five untrained subjects (U). The oxidative enzyme activities were 100% greater in T than in U, and VO2 max was 50% higher. A greater proportion of ATP regeneration occurred through oxidative processes in T than in U (smaller leg lactate release and smaller muscle lactate accumulation). The respiratory exchange ratio together with the local leg respiratory quotient indicated a greater contribution of fat to oxidative metabolism in T than U (53 vs. 33%). No difference, however, in the ratio of plasma free fatty acid extraction to O2 extraction by the working legs was found between T and U. Thus it could be calculated that a greater fraction of fat oxidation would have been covered by intramuscular triglycerides in T than in U (34 vs. 15%, P less than 0.05). T in comparison to U were further characterized by a smaller glycogen breakdown and a smaller glucose uptake, which may have been one contributing factor that prevented the blood glucose level from falling in T. The greater leg muscle citrate concentration in T could have been one factor mediating a lower carbohydrate utilization as a response to an increase in the relative proportion of fat oxidation.

Bicycling↗
PubMed1987

Preservation of myocardial high-energy phosphates in open-heart surgery with deep general hypothermia and multidose crystalloid cardioplegia.

Myocardial energy metabolism during deep general hypothermia (20 degrees C) and multidose crystalloid cardioplegia, and also during subsequent reperfusion, was studied in eight patients undergoing isolated aortic valve replacement. Six serial transmural biopsy samples from the left ventricular apex were analyzed for high-energy phosphates and their degradation products. Reductions in ATP, total adenine nucleotide content and energy charge were insignificant during cardioplegia, as were changes in adenosine and uric acid concentrations. During reperfusion, however, there was slight but significant reduction in total adenine nucleotide content, despite adequate oxygenation as indicated by reversal of lactate accumulation. These observations suggest that the reperfusion phase is accompanied by metabolic aberrations which are not overcome by good oxygenation in relation to the metabolic rate.

Adenine Nucleotides↗
PubMed1986

Effect of beta 1-selective and non-selective beta-blockade on work capacity and muscle metabolism.

Six well-trained men were studied while performing a maximal bicycle exercise. The seven experiments included in this study were randomized in a double-blind cross-over fashion. On each occasion the subjects were given either placebo or 40, 80, or 160 mg propranolol (non-selective blockade) or 25,50, or 100 mg atenolol (beta 1-selective blockade). After completion of the study each subject had performed once under each of the seven treatments. Heart rate, maximal oxygen uptake (Vo2max), blood lactate and performance time to exhaustion were measured. A muscle biopsy from vastus lateralis was taken at exhaustion after placebo, 80 mg propranolol and 50 mg atenolol trials, for analysis of ATP, creatine phosphate (CP), glucose-6-phosphate (G-6-P), glucose and lactate. The performance time was reduced (P less than 0.05-0.001) with both blockers compared to placebo. At an equal heart rate reduction, Vo2max was equally reduced by both blockers. Performance time, on the other hand, was reduced to a greater extent (P less than 0.05) with propranolol. ATP and CP levels were decreased (P less than 0.05) by both drugs. G-6-P, however, was lower (P less than 0.05) with propranolol than with either placebo or atenolol. No difference was observed between placebo and atenolol. In conclusion, both beta1-selective and non-selective blockade reduced short-term maximal exercise capacity. The major limiting factor seems to be the reduction in oxygen transport. The finding that at an equivalent reduction in Vo2max propranolol reduced performance time to a greater extent than atenolol suggests that beta 2-blockade may reduce performance by mechanisms additional to those that affect oxygen transport.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1986

Plasma neuropeptide Y-like immunoreactivity and catecholamines during various degrees of sympathetic activation in man.

Neuropeptide Y-like immunoreactivity (NPY-LI) and catecholamine concentrations in plasma were analysed during and after 60 min of physical exercise at a work load corresponding to 70% of individual maximal oxygen uptake in nine healthy men of average physical fitness. Systemic plasma NPY-LI increased progressively from 18 +/- 3 to 81 +/- 19 pmol X 1(-1) in parallel with a 10-fold increase in noradrenaline (NA) concentration. The increase in plasma NPY-LI during exercise and the decrease after completion of exercise were much slower than the corresponding changes in NA concentration. This difference is probably related to a slower diffusion of NPY into systemic circulation after release, as well as to a longer half-life of NPY than of NA in plasma. Reversed phase HPLC and sephadex G-50 gel-filtration chromatography revealed that the main component of NPY-LI in plasma during exercise eluted in a similar position as synthetic human NPY. During exercise plasma NPY-LI correlated well with the plasma concentration of NA (r = 0.80), but not with that of adrenaline (ADR), suggesting a neuronal origin of NPY. The self-ratings of perceived exertion (RPE) were well correlated with the plasma concentrations of both NPY-LI and NA. No clear-cut veno-arterial concentration difference was observed for NPY-LI. Isometric handgrip and orthostatic test doubled plasma NA concentrations but did not cause any increase in plasma NPY-LI. No change in plasma tachykinin-like immunoreactivity was detected during exercise. The present data suggest that NPY is released together with NA during strong, but probably not during mild, sympathetic activation under physiological conditions in man.

Adult↗
PubMed1986

Temperature-induced changes in metabolic and hormonal responses to intensive dynamic exercise.

Seven male subjects performed intensive cycle exercise to exhaustion at subnormal muscle temperature (Tm, 29 +/- 2.8 degrees C). Exercise at exactly the same rate of exercise and duration (370 +/- 34 W, 1.5 +/- 0.15 min) was then repeated with normal Tm (35 +/- 0.9 degrees C). During exercise both the arterial (a) and femoral venous (fv) contents of oxygen were significantly higher at subnormal than at normal Tm, because of the higher haemoglobin concentration, but the a-fv oxygen difference was the same in the two situations. The rate of increase in lactate concentration in both arterial and venous blood during exercise was the same in two situations. During exercise the plasma concentrations of adrenaline and noradrenaline in arterial and venous blood were significantly higher at subnormal than at normal Tm. At rest and after exercise the calf blood flow was significantly reduced at subnormal Tm. At the end of exercise the concentrations of glucose-6-phosphate and lactate in the muscle were significantly higher at subnormal Tm than in the muscle of normal temperature. These findings suggest that there was a greater increase in glycolysis in the muscle of subnormal temperature during exercise, possibly as a result of impaired work efficiency and/or reduced blood flow in the cold muscle.

Adult↗
PubMed1986

Epinephrine-induced changes in muscle carbohydrate metabolism during exercise in male subjects.

Epinephrine increases glycogenolysis in resting skeletal muscle, but less is known about the effects of epinephrine on exercising muscle. To study this, epinephrine was given intraarterially to one leg during two-legged cycle exercise in nine healthy males. The epinephrine-stimulated (EPI) and non-stimulated (C) legs were compared with regard to glycogen, glucose, glucose 6-phosphate (G6P), alpha-glycerophosphate (alpha-GP), and lactate contents in muscle biopsies taken before and after the 45-min submaximal exercise, as well as brachial arterial-femoral venous (a-fv) differences for epinephrine, norepinephrine, lactate, glucose, and O2 during exercise. During exercise the arterial plasma epinephrine concentration was 4.8 +/- 0.8 nmol/l and the femoral venous epinephrine concentrations were 10.3 +/- 2.1 and 3.9 +/- 0.6 nmol/l, respectively, in the EPI and C leg. During exercise the a-fv difference for lactate was greater (-0.41 +/- 0.14 vs. -0.21 +/- 0.14 mmol/l; P less than 0.001), and the a-fv difference for glucose was smaller (0.07 +/- 0.12 vs. 0.24 +/- 0.12 mmol/l; P less than 0.01) in the EPI than in the C leg, but the a-fv differences for O2 were similar. Muscle glycogen depletion (137 +/- 63 vs. 99 +/- 43 mmol/kg dry muscle; P less than 0.1) and the muscle concentrations of glucose (P less than 0.05), alpha-GP (P less than 0.1), G6P (P greater than 0.1), and lactate (P greater than 0.1) tended to be higher in the EPI than the C leg after exercise. These findings suggest that physiological concentrations of epinephrine may enhance muscle glycogenolysis during submaximal exercise in male subjects.

Adult↗
PubMed1986

Myocardial metabolism during aortic valve replacement. I. Hypothermic crystalloid cardioplegia with mannitol.

Myocardial energy metabolism during hypothermic potassium cardioplegia with addition of mannitol was studied in five patients undergoing aortic valve replacement. Myocardial biopsies were taken from the left ventricle 10 min after the aortic cross-clamping and immediately before declamping and were analyzed for ATP, lactate and glycogen. The ATP concentration fell (13.2 +/- 3.6-11.0 +/- 4.3 mmol X kg-1 dry muscle), the lactate concentration rose (61.5 +/- 17.6-86.6 +/- 13.3) and glycogen decreased (181 +/- 54-143 +/- 3 mmol X kg-1 d.m.). Use of mannitol in a crystalloid cardioplegia solution does not prevent pronounced anaerobic metabolism in the myocardium during aortic valve replacement.

Adenosine Triphosphate↗
PubMed1986

Myocardial metabolism during aortic valve replacement. II. Bolus infusion of cold blood for cardioplegia.

Myocardial energy metabolism during hypothermic potassium cardioplegia with blood as the cardioplegia vehicle, given in one or two bolus doses, was studied in eight patients undergoing aortic valve replacement. Myocardial biopsies were taken from the left ventricle 10 min after aortic cross-clamping (a.c.) and immediately before declamping (d.c.) and were analyzed for ATP, creatine phosphate (CP), creatine (C) and lactate. The interindividual range of myocardial temperature was 11-19 degrees C at 10 min a.c. and 11-25 degrees C immediately before d.c. The myocardial ATP concentration fell (17.2 +/- 5.7-12.8 +/- 2.8 mmol X kg-1 dry muscle), the lactate concentration rose (64.7 +/- 35.8-136 +/- 33.8 mmol X kg-1 d.m.) and the total creatine pool (CP + C) was unchanged. Hypothermic blood cardioplegia conferred fairly good initial protection of the myocardium, but the reduction in ATP and the great lactate accumulation towards the end of cardioplegia, especially in patients with myocardial temperature reaching 19-25 degrees C, indicates that such protection is adequate only if the myocardial temperature is maintained between 11 and 18 degrees C.

Adenosine Triphosphate↗