Karel Vondra

Enzyme activities in quadriceps femoris muscle of obese diabetic male patients.

SummaryIn biopsy samples of the lateral part of the quadriceps femoris muscle of 6 obese diabetic male patients and of 11 obese males with a normal glucose tolerance, the activities of 7 enzymes of energy metabolism were estimated: hexokinase, cytoplasmic glycerol-3-phosphate: NAD dehydrogenase, triosephosphate dehydrogenase, lactate dehydrogenase, citrate synthase, malate dehydrogenase and 3-hydroxyacyl-CoA dehydrogenase. The obese diabetic male patients exhibited decreased activities of enzymes of carbohydrate breakdown and cytoplasmic NAD regeneration. Enzymes connected functionally with aerobic metabolism were less affected. The unchanged activity of 3-hydroxyacyl-CoA dehydrogenase points to an increased role of fatty acid catabolism in the muscle.

Effects of sleep deprivation on the activity of selected metabolic enzymes in skeletal muscle

SummaryThe effect of 120-h sleep deprivation on the activity of selected enzymes of energy metabolism in skeletal muscle was studied in seven healthy volunteers. The results showed a significant decrease in the activity of malate dehydrogenase, citrate synthase, glycerol-3-phosphate dehydrogenase and lactate dehydrogenase. Triosephosphate dehydrogenase, hexokinase, and hydroxyacyl-CoA-dehydrogenase activities showed an insignificant decrease. The findings are indicative of (1) decreased aerobic oxidation capacity; (2) reduced function of reducing-equivalent carriers from cytosol across the mitochondrial membrane; (3) relative accentuation of the non-aerobic glycolytic pathway; (4) a prediabetic type of muscle metabolism.

M. Quadriceps femoris of man, a muscle with an unusual enzyme activity pattern of energy supplying metabolism in mammals.

Summary1.The following enzyme activities were estimated in needle-biopsy samples of the lateral part of the human quadriceps femoris muscle: triosephosphate dehydrogenase (TPDH), lactate dehydrogenase (LDH), NAD: glycerol-3-phosphate dehydrogenase (GPDH), hexokinase (HK), NAD: malate dehydrogenase (MDH), citrate synthase (CS) and hydroxyacyl-CoA dehydrogenase.2.Although the enzyme activities in muscle of women were lesser than in those of men, no difference was found in the calculated enzyme activity ratios. There is thus no sex-dependent metabolic type-differentiation in this muscle.3.The human quadriceps femoris is a low-activity muscle, in comparison with muscles of homoiotherm laboratory animals. The enzyme activity ratio of TPDH to CS, characterizing the glycolytic pyruvate formation oo aerobic oxidative capacities, shows this muscle to be of an intermediate type in this respect, similarly as the extensor digitorum longus of the rat. The relatively very high capacity of glucose phosphorylation (HK), the high aerobic regeneration of cytoplasmic dehydrogenated NAD (GPDH) and the very low anaerobic regeneration (LDH), show the unusually high proportion of carbohydrates (glucose) which can be broken down aerobically.

Enzyme activity patterns of energy supplying metabolism in the quadriceps femoris muscle(Vastus lateralis)

Summary1.In 3 groups of men, differing as to the amount and intensity of physical training loads, increasing in the order “sedentary”:“sporting”:“athletic”, enzyme activities were estimated in biopsy samples of m. quadriceps femoris (vastus lateralis). The enzymes were: Hexokinase (HK), NAD: glycerol-3-phosphate dehydrogenase (GPDH), triosephosphate dehydrogenase (TPDH), lactate dehydrogenase (LDH), citrate synthase (CS), NAD: malate dehydrogenase (MDH), and 3-hydroxyacyl-CoA dehydrogenase (HOADH). Indicators of laboratory performance and whole-body metabolic capacities (maximal oxygen consumption etc.) were estimated in the “sporting” and “athletic” groups.2.In the 2 latter groups, distinguished by greater physical activity, the atypical enzyme activity pattern, remarkable by a low activity of LDH and high relative activities of GPDH and HK, as reported earlier in a sedentary group (Basset al., 1975a), disappeared. The possibility of the atypical low LDH enzyme activity pattern as resulting from lack of bodily exertion is discussed.3.The moderately trained “sporting” group distinguishes itself from the “sedentary” one mainly by a higher activity of LDH and by lower activities of GPDH and MDH. In the intensively trained “athletic” group, enzymes connected to aerobic oxidation (MDH, CS, HOADH) and GPDH also show higher activities than in the “sporting” group. The difference between the two more active groups is further borne out by a higher maximum oxygen uptake and carbon dioxide release of the well-trained “athletic” group. This difference of enzyme activity pattern may not be confined to the quadriceps femoris muscle.

Metabolic changes in the quadriceps femoris muscle of obese people

Summary1.In biopsy samples of the lateral part of m. quadriceps femoris of 49 obese and 14 lean persons the activities of the following enzymes were investigated: triosephosphate dehydrogenase (TPDH), glycerolphosphate: NAD dehydrogenase (GPDH), lactate dehydrogenase (LDH), hexokinase (HK), malate: NAD dehydrogenase (MDH), citrate synthase (CS) and hydroxyacyl-CoA dehydrogenase (HOADH).2.The muscles of obese had an increased activity ratio of TPDH to CS and to HK, respectively, caused in muscles of female obese subjects by an increase of TPDH activity, in those of obese men rather by a decrease of CS and HK activities.3.Cluster analysis brought to light the existence of three major groups. Group 1 (low activity-low LDH group), consisting of muscles of female obese subjects only, exhibited low activities of all enzymes investigated, that of LDH being so low as to possibly induce a serious deficiency of anaerobic metabolism under working conditions. Group 2 (medium enzyme activity group) was characterized by medium enzyme activities, similar to that of lean controls (included in this group). This consisted of subjects of both sex. Group 3 (high enzyme activity group) consisted of obese of both sex. It was distinguished by high enzyme activities, especially of LDH. It is suggested that the groups of similar enzyme activity patterns might reflect different stages, types and/or genesis of obesity.

Enzyme activity patterns of energy metabolism in skiers of different performance levels (M. quadriceps femoris)

SummaryChanges in the activity of muscle enzymes of energy metabolism were studied in two groups of skiers (A, B) with a different sports performance (triosephosphate dehydrogenase-TPDH, lactate dehydrogenase-LDH, glycerol-3-phosphate dehydrogenase-GPDH, hexokinase-HK, malate dehydrogenase-MDH, citrate synthase-CS, hydroxyacyl, CoA dehydrogenase-HOADH).1.In a group of ski-runners (A) significantly higher activities of CS, MDH, HOADH in the preparatory period (October) and also at the end of the competition period (March) were found in athletes with higher sports performance.2.Significantly lower activities of LDH, GPDH, MDH, CS, HOADH were found in downhill skiers (group B).3.Some significant correlations were established, both between the activities of individual enzymes (TPDH, GPDH, HK, CS, HOADH) and between the enzymes and indicators of functional capacity (MDH, CS, HOADH, VO2 max, HR max, O2-pulse max, body fat, laboratory performance).

Changes in maximal aerobic power, aerobic capacity, and muscle enzyme activities at two stages of the annual training cycle in ski-runners.

SummaryChanges of cardiorespiratory capacity, of the activity of seven enzymes involved in energy metabolism and of laboratory endurance were investigated in a group of nine male ski-runners before and after exhausting training and a competing period during the winter.Despite the decrease in laboratory endurance and total work oxygen consumption between the investigations,

Effect of Protracted Intermittent Fasting on the Activities of Enzymes Involved in Energy Metabolism, and on the Concentrations of Glycogen, Protein and DNA in Skeletal Muscle of Obese Women

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