Metabolites of the aminoacetone pathway in blood after exercise.

The following article reports (A) data on glyoxalase I activity in skeletal muscle of untrained men and endurance--trained athletes, and (B) the presence at rest and the rise in blood after exercise of two metabolites of the aminoacetone pathway of amino acid degradation in man. Glyoxalase I showed an average activity of 191 +/- 38 U/g wet weight (37 degrees C) in bioptic samples of m.vastus medialis quadricipitis of young adults whereas this was of 235 +/- 64 U/g (p < 0.15) in athletes. After an ergometer exercise test with increasing intensity (50 to 400 Watt (W), 3 min-steps) by well trained cyclists, blood (L-(+)-lactate increased to 10.12 mmole/liter, whereas methylglyoxal rose by 48.4% and D-(-)-lactate by 70% (resting levels 92 and 100/mumole/liter, respectively). The possible physiologic significance of the assumed aminoacetone pathway was discussed with respect to muscular activity.

Vitamin B2 status in athletes and the influence of riboflavin administration on neuromuscular irritability.

In order to obtain information on the vitamin B2 status in athletes in training, the following aspects were investigated: in one group of athletes, riboflavinuria at rest, during the autumn and winter months (mean values 23.8 and 9.45 mug/h, respectively); in the second group (n = 18), the activity of the nicotinamide-adenine-dinucleotide-phosphate-dependent red blood cell glutathione reductase (EC 1.6.4.2) and its activation by added flavin adenine dinucleotide. In 8 athletes, activation coefficients higher than 1.25 were found, indicating a biochemical deficiency of riboflavin. Erythrocyte transketolase (EC 2.2.1.1) was activated by more than 25% with added thiamine pyrophosphate in 12 cases. In muscle samples of 10 healthy patients (fresh fractures or removing of metal plates from old fractures), glutathione reductase (mean activity 0.846 +/- 0.458 U/g wet weight) was activated by more than 25% in 5 cases. Administration of 10 mg of riboflavin per os resulted in moderate lowering of neuromuscular irritability (musculi vastus medialis and lateralis quadricipitis) particularly for 0.1-msec rectangular stimuli.

Serum gamma-glutamyl transpeptidase and physical exercise.

The immediate and delayed influence of exercise of variable type, duration and intensity on the serum gamma-glutamyl transpeptidase activity (gamma-GT) has been examined in athletes and untrained persons. The possible effects of exercise-induced changes in other parameters (plasma free glutamate, serum triglyceride, haemoconcentration) on the measured postexercise serum gamma-GT have been discussed, partly on the basis of our own experimental data. It appears that neither exercise itself, nor any one of the above mentioned factors (excepting a slight, transient effect of haemoconcentration after brief, intensive exertion) have noticeable influence on serum gamma-GT. Determinations of this enzyme for diagnostic purposes are therefore likely to be used without regard to acute and chronic exercise history in man.

Resting muscle levels and the influence of exercise on serum amino acid-arylpeptidase activity in man.

Activities of amino acid arylamidases in skeletal muscle and serum of healthy male subjects were investigated using various substrates (Ala-, Leu-, Phe- and S-benxylcysteine-4-nitroanilides). At rest, there is no agreement between muscle and serum activity patterns. After physical exercise, the serum increase of Ala-, Leu- and Phe-AP activities is closely correleated to their respective activities in resting muscles. Since there is no relationship of the postexercise increase of amino acid arylpeptidase activitiy and exercise-induced intrasvascular haemolysis, it appears highly probable that the origin of the serum activity increase after physical work is skeletal muscle.

Kearns-Sayre syndrome: primarily a mitochondriopathy?

Histopathological changes of the external eye muscles and of the peripheral skeletal muscles of 2 patients with Kearns-Sayre syndrome are demonstrated histochemically and electron microscopically. In one case the progression of the mitochondrial anomalies in this disease was documented through ultrastructural investigations of muscle biopsies over a period of 17 years. By freeze-fracture the membrane fracture faces of the transformed mitochondrial were examined in both patients. Biochemical results of one patient show that energy production by glycolysis is distinctly decreased with respect to oxydation. Clinical, morphological and biochemical results support the hypothesis that the Kearns-Sayre syndrome is caused by a primary mitochondriopathy which is not limited to the musculature.

Enzyme activities of human myocardium: creatine kinase and hexose phosphate isomerase.

Creatine kinase (CK) and hexose phosphate isomerase (PHI) activities were determined in 36 samples of human heart muscle obtained from patients during cardiovascular surgery. With one exception, CK activities were higher than any reported so far in the literature (papillary muscle, left ventricle: 2,521 +/- 776 IU/g wet weight at 37 degrees C). PHI Activities, the first time measured, are comparable to those in skeletal muscle (200-400 U/g, higher in papillary muscle than in the right auricle). The activities of both enzymes determined correlate significantly (all samples considered together: r = 0.773; p < 0.001). Results are discussed with respect to their possible clinical interest as well as their significance for myocardial metabolism.

Fumarase activity in skeletal muscle of man.

Soluble extracts of human skeletal muscle have a fumarase activity of 31.2 +/- 7.27 (M. vastus lateralis quadricipitis) or 30.9 +/- 8.0 U/g wet weight at 37 degrees C (M. deltoideus). The distribution of activities in the 36 muscle samples studies is not gaussian. There is a significant correlation between the activities of citrate synthase and fumarase (r = + 0.881; p less than 0.001) in all investigated muscles, excepting M. vastus lateralis quadricipitis.

Citrate synthase activity in human skeletal muscle.

Citrate synthase activity in soluble human muscle extracts (KCl-containing triethanolamine buffer) amounts to 17.5+/-6.97 U/g wet weight at 37 degrees C (n=36 healthy male subjects). Double determinations, both using two procedures and with muscle samples divided into two pieces and analyzed separately, gave very good reproducibilities. The possible causes of the comparatively high values are discussed. Significant correlations of citrate synthase activity with NADP-linked isocitrate dehydrogenase (r=+0.826) and hexose phosphate isomerase (r=-0.582) were found. The distribution of citrate synthase activity in the samples studied is not of the normal type but appears to be binomial.

Enzyme activities in skeletal muscle of 13-15 years old adolescents.

The activity of 22 enzymes of energy metabolism was determined in m. vastus lateralis quadricipitis of 14 adolescents aged 13-15 years (7 girls) and 14 adults aged 22 to 42 years (7 female subjects). The measurements were performed kinetically, at 37 degrees C, using optimal or near-to-optimal procedures. With the exception of one enzyme, enolase, no differences between sexes were observed in the two age groups. Glycolytic enzymes, including fructose-6-phosphate kinase, showed no significant differences in their activity in adults as compared to adolescents. The activity of enolase was lower in females of both age groups, but no difference due to age was found in this respect. Of the oxidative enzymes studied, only citrate synthase showed no significant difference in adults vs adolescents, whereas the activities of lipoamide dehydrogenase (+ 40%), NADP-isocitrate dehydrogenase (+ 44%), fumarase (+ 24.5%), total malate dehydrogenase (+ 42.2%) and NADH-dehydrogenase (+ 39%) were all significantly higher in the latter group. Aspartate aminotransferase was also 44% higher in adolescents. The possible physiological importance of these observations is discussed with regard to the functional capacity of the skeletal muscle. The hypothesis was considered that adolescents of this age may have a glycolytic capacity comparable to adults, but that they may oxidize pyruvate at a rate higher than adults.

Serum aldolase isoenzymes in athletes at rest and after long-lasting exercise.

Athletes in training have significantly higher levels of serum aldolase activity at rest when compared to nonathletes. This is due to the higher level (and higher proportion) of aldolase isoenzyme A, predominant in muscle. At rest, athletes with a history of infectious hepatitis show significantly higher proportional and absolute levels of aldolase B, predominant in liver. Long-lasting exercise leads to a rise in serum aldolase activity, which must be ascribed to the increase in isoenzyme A. Significant post-exercise changes in isoenzyme B were not observed. There was no correlation between changes in serum hemoglobin, as reflecting intravascular hemolysis, and changes in serum aldolase activity. The data are discussed in regard to the existing hypotheses regarding increases in serum enzyme activity after physical exercise.