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Biomedical subjects

B Saltin

Publications and source records attributed to B Saltin.

At least 235 records · Page 13Linked to original sources
PubMed1975

Effects of chronic ethanol abuse on structure and enzyme activities of skeletal muscle in man.

Biopsies from vastus lateralis muscle of male patients suffering from chronic ethanol abuse were studied with regard to histochemical reactions of ATPase and NADH-diaphorase; enzymatic activities of triosephosphate dehydrogenase (TPD), lactate dehydrogenase (LD), and cytochrome c oxidase (cytox); content of ATP, creatine phosphate, and glycogen; and volume fractions of fat, mitochondria, and fibrillar and extrafibrillar space. The results were compared with those from controls without known abuse of ethanol. The relative numbers of fibers were the same in two groups, but the size of the fast-twitch-glycolytic (white) fibers was diminished in the alcoholic group. The activities of TPD and LD were diminished in skeletal muscle of the alcoholics. This is most probably caused by the reduced amount of fast-twitch-glycolytic tissue, as there was a good correlation between this amount and the activity of the two enzymes. The activity of cytox was slightly lower in muscle of the alcoholics than in that of the controls. The volume fraction of mitochondria was lower in the alcoholic group than in the control group. Volume fractions of fat and fibrillar and extrafibrillar space were equal in the two groups. No significant differences were found in the amount of glycogen and ATP in the muscle of the two groups. However, the content of creatine phosphate is higher in the alcoholic group than in the control group.

Adenosine Triphosphatases↗
PubMed1975

Metabolic characteristics of fibre types in human skeletal muscle.

Muscle biopsy samples were obtained from healthy subjects in order to evaluate quantitative differences in single fibres of substrate (glycogen and triglyceride) and ion concentrations (Na+ and K+) as well as enzyme activity levels (succinate-dehydrogenase, SDH; phosphofructokinase, PFK; 3-hydroxyacyl-CoA-dehydrogenase, HAD; myosin ATPase) between human skeletal muscle fibre types. After freeze drying of the muscle specimen fragments of single fibres were dissected out and stained for myofibrillar-ATPase with preincubations at pH's of 10.3, 4.6, 4.35. Type I ("red") and II A,B, and C ("white") fibres could then be identified. Glycogen content was the same in different fibres, whereas triglyceride content was highest in Type I fibres (2-3 X Type II). No significant differences were observed for Na+ and K+ between fibre types. The activity for the enzymes studied were quite different in the fibre types (SDH and HAD, Type I is approximately 1.5 X Type II; PFK Type I is approximately 0.5 X Type II, Myosin ATPase Type I is approxiamtely 0.4 X Type II). The subgroups of Type II fibres were distinguished by differences in both SDH and PFK activities (SDH, Type II C is greater than A is greater than B; PFK, Type II B is greater than A is approximately C). It is concluded that contractile and metabolic characteristics of human skeletal fibres are very similar to many other species. One difference, however, appears to be than no Type II fibres have an oxidative potential higher than Type I fibres.

Adenosine Triphosphatases↗
PubMed1975

Cardiopulmonary function in former girl swimmers and the effects of physical training.

Sixteen former girl swimmers were studied in 1971 before and after 12 weeks of physical training. These girls constituted a representative selection from a group of 30 girls swimmers studied in 1961 (3). Maximal oxygen uptake increased by 14%, to 2.47 l/min, whereas heart volume and vital capacity remained unchanged. Cardiac output and intrapulmonary gas exchange were also studied in 6 girls. Cardiac output in maximal exercise was 15.3 l/min; heart rate, 185 beats/min; stroke volume, 83 ml; and the arteriovenous oxygen diffence, 15.6 ml/100 ml. The stroke volume did not show the usually good correlation with heart volume. Normal values for V-E/V-O2, V-A/VO-2, V-A/Q, and PAO2-Pao2 were found both at rest and during exerice. The increase in maximal oxygen uptake after training was related to the increase in stroke volume. No increase was found in values for pulmonary gas exchange nor in the maximal arteriovenous oxygen difference. The results obtained suggest that a long period of previous intense physical training does not significantly influence the maximal aerobic power later in life when again sedentary. Moreover, the observed increase of 14% in VO2, max after 12 weeks of training may not be large enough to prove any advantageous effects when training is resumed.

Carbon Dioxide↗
PubMed1975

Work capacity, muscle strength and SDH activity in both legs of hemiparetic patients and patients with Parkinson's disease.

In recent muscle metabolic studies, patients with moderate upper motor neuron lesions showed marked difficulty in performing an equal submaximal work load (bilaterally) in two-legged exercise. For a better evaluation of these patients, studies were performed on each leg separately. Six patients with Parkinson's disease and six with moderate hemiparesis were studied. During one-legged submaximal and maximal exercise heart rate, oxygen uptake, and blood lactate were determined. Maximal voluntary contraction in knee and ankle flexion and extension for each leg was measured. Succinate dehydrogenase (SDH) activity in the thigh muscles was determined. During submaximal exercise, oxygen uptake, heart rate and blood lactate increased more in the paretic leg of hemiparetic patients and in the more affected leg of the Parkinson patients. In hemiparetic patients maximal voluntary contraction of flexors and extensors of the knee was significantly reduced in the paretic leg but was reduced even in the nonparetic knee flexors. SDH activity was very low in both legs in all patients and lowest in the paretic and more affected leg, respectively. It is concluded that (a) the general muscle inactivity per se, secondary to the neurological disorder, may lead to a reduced work capacity; (b) the increased heart rate and blood lactate level seem to be correlated to the relative exercise level of each leg; and (c) in patients with impaired muscle function of one or both legs, evaluation of each leg separately with regard to work capacity and muscle metabolism is of value.

Adult↗
PubMed1974

Selective glycogen depletion pattern in human muscle fibres after exercise of varying intensity and at varying pedalling rates.

1. Glycogen depletion pattern in human skeletal muscle fibres was studied after bicycle exercise of varying intensity performed at different pedalling rates. Work intensities studied were equivalent to 30-150% of V(O) (2) max. with pedalling rates of 30-120 rev/min.2. Glycogen depletion increased dramatically with increasing exercise intensity; depletion was 2.7 and 7.4 times greater respectively at workloads demanding 64 and 84% V(O) (2) max. than at workloads calling for 31% V(O) (2) max. Even greater rates of glycogen utilization occurred at supramaximal loads.3. Slow twitch, high oxidative (ST) fibres were the first to lose glycogen (reduced PAS staining) at all workloads below V(O) (2) max. Progressive glycogen depletion occurred in fast twitch (FT) fibres as work continued. Large quantities of glycogen remained in the muscle after 3 hr of exercise at low exercise intensity. This was almost exclusively found in FT fibres. At workloads exceeding maximal aerobic power, there was an initial depletion of glycogen in both fibre types. Varying the pedalling rate and, thus, the total force exerted in each pedal thrust had no effect on the pattern of glycogen depletion in the fibres.4. Results point to primary reliance upon ST fibres during submaximal endurance exercise, FT fibres being recruited after ST fibres are depleted of glycogen. During exertion requiring energy expenditure greater than the maximal aerobic power, both fibre types appeared to be continuously involved in carrying out the exercise.

Adenosine Triphosphatases↗
PubMed1974

Selective glycogen depletion in skeletal muscle fibres of man following sustained contractions.

1. Six healthy males performed sustained contractions with different tensions related to their maximal voluntary contraction (MVC). The isometric exercise consisted of efforts to extend the knee when flexed at an angle of 90 degrees .2. Biopsy samples were taken from the lateral portion of M. quadriceps femoris before and after different periods (6-45 min) during a series of sustained contractions. Total glycogen content was determined on each muscle sample. In order to evaluate whether the glycogen depletion occurred preferentially in slow twitch (ST) or fast twitch (FT) fibres, serial sections of the muscle samples were stained for myofibrillar ATPase and glycogen (PAS reaction).3. In all experiments a selective glycogen depletion was observed. At low tensions, the ST fibres and at higher tensions the FT fibres became glycogen depleted. The critical tension at which this conversion in glycogen depletion from ST to FT fibres took place was 20% MVC.4. It is concluded that at sustained contractions of less than 20% MVC there is a major reliance upon ST fibres and above that level a primary dependence upon FT fibres. It is further suggested that restriction of blood flow and thus availability of oxygen at forces higher than 20% MVC may be the explanation for the present findings.

Adenosine Triphosphatases↗