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Biomedical subjects

V Vihko

Publications and source records attributed to V Vihko.

At least 55 records · Page 3Linked to original sources
PubMed1984

Prednisolone decreases exercise-induced acid hydrolase response in mouse skeletal muscle.

Male NMRI-mice were subjected to exhaustive treadmill exercise. 3 and 6 days after the exertion, quadriceps femoris muscles were examined histologically and analyzed for acid hydrolases in order to follow the degree and progress of injuries. Prednisolone (PRED), an anti-inflammatory corticosteroid, was given to some of the animals in order to modify the exercise response. The PRED administration began 14 h before exercise and continued until the end of the experiment (6 days). The doses were 25 and 50 mg . kg-1 i.p. twice a day. The activities of both arylsulphatase and beta-glucuronidase increased significantly in the exercise control group after 3 and 6 days. The increase in activity correlated with fibre necrosis and an abundant infiltration of inflammatory cells, and was greatest after 3 days. After 6 days the inflammatory response decreased and regenerating muscle fibres were seen. PRED decreased the exercise-induced acid hydrolase response. The decrease was most prominent after 3 days with PRED 50 mg . kg-1 . day-1. PRED also diminished degeneration and inflammation. The results suggest that the decrease in acid hydrolase activities was due to a lesser infiltration of inflammatory cells to the injured area.

Animals↗
PubMed1984

Endurance training decreases the alkaline proteolytic activity in mouse skeletal muscles.

Alkaline and myofibrillar protease activities of rectus femoris, soleus, and tibialis anterior muscles and the pooled sample of gastrocnemius and plantaris muscles were analyzed in male NMRI-mice during a running-training program of 3, 10, or 20 daily 1-h sessions. The activity of citrate synthase increased during the endurance training, reflecting the increased oxidative capacity of skeletal muscles. The activities of alkaline and myofibrillar proteases continually decreased in the course of the training program in all muscles studied. Instead, the activity of beta-glucuronidase (a marker of lysosomal hydrolases) increased in all muscles. The highest activities were observed at the beginning of the training program. Present results, together with our earlier observations, show that the type of training, running as opposed to swimming, modulates the training responses in alkaline protease activities. Further, diverse adaptations in the activities of alkaline proteases and a lysosomal hydrolase suggest difference in the function of different proteolytic systems.

Animals↗
PubMed1984

Autophagic response to strenuous exercise in mouse skeletal muscle fibers.

Strenuous physical exercise induces necrosis of skeletal muscle fibers and increases lysosomal enzyme activities in surviving muscle fibers. This study examines the ultrastructural basis of the stimulation of the lysosomal system in mouse vastus medialis muscle during the appearance and repair of exercise-induced (9 h of running) injuries. Necrotic fibers appeared the day after exercise and an inflammatory response with the replacement of necrotic fibers by phagocytes was highest 2-3 days after exertion. Ultrastructural study of surviving muscle fibers revealed numerous autophagic vacuoles, residual bodies, and spheromembranous structures at the periphery of myofibers, especially in fibers adjacent to necrotic fibers. The autophagic response was most prominent between 2 and 7 days after exertion. Autophagic vacuoles with double or single limiting membranes contained mitochondria at various stages of degradation. Vacuolar and multilamellar structures were also observed in regenerating muscle fibers. The structure of injured skeletal muscle fibers returned to normal within 2 weeks. It is proposed that increased autophagic activity could be related to the breakdown of cellular constituents of surviving muscle fibers to provide structural elements for regenerating muscle fibers.

Animals↗
PubMed1984

Acid proteolytic activities in mouse liver and muscle tissues after treatment with protease inhibitor leupeptin.

The activities of acid proteolytic enzymes were assayed in the liver and muscular tissues of mice (Mus musculus) 1, 6 and 24 hr after the administration of a protease inhibitor leupeptin (i.p., 15.5 mg/kg body wt). Leupeptin administration induced a strong inhibition of cathepsin B and a moderate inhibition of cathepsin C and acid autolytic rate in mouse liver 1 hr after injection. Thereafter the inhibition reduced and disappeared during 24 hr. The activity of cathepsin D was increased in liver 6 and 24 hr after injection. The activity of beta-glucuronidase was not affected by the leupeptin treatment. The administration of leupeptin did not affect the rate of acid autolysis and the activities of cathepsin C and D in cardiac and skeletal muscles. A slight increase in cathepsin B activity was observed 1 hr after leupeptin treatment in calf muscles. The cause of both tissue and enzyme specific changes after leupeptin treatment is discussed.

Animals↗
PubMed1984

Lysosomal changes related to exercise injuries and training-induced protection in mouse skeletal muscle.

Three experiments were designed to study the lysosomal changes associated with the development and maintenance of the endurance training induced resistance against exercise injuries in mouse skeletal muscles. The activities of arylsulphatase, cathepsin C, cathepsin D, and beta-glucuronidase were assayed from the red part of mouse quadriceps femoris muscle 4 days after prolonged strenuous running of 4-9 h duration. Exercise injuries were characterized by necrotic fibers and focal inflammation. Strenuous running of untrained mice induced necrotic lesions and a 4-5 fold increase in the activities of lysosomal enzymes. This lysosomal response was considerably reduced already by daily training bouts on the 3 days preceding the strenuous exertion. Simultaneously exercise injuries were markedly reduced. Extending the endurance training program increased the running ability of mice and further reduced the necrotic lesions and lysosomal changes induced by the strenuous exercise. The detraining of 1 week after the termination of regular endurance training considerably increased the degree of exercise induced lysosomal response. The detraining of longer durations further increased the lysosomal response and no effect of prior endurance training existed after 1 month detraining. Our observations suggest that the severity of exercise injuries is related to the strength of the exercise stimulus and the level of preceding physical activity and can be characterized by the lysosomal changes.

Animals↗
PubMed1984

Vitamin E deficiency and the susceptibility to lipid peroxidation of mouse cardiac and skeletal muscles.

Effects of a short-term vitamin E deficiency on some lipid peroxidative properties were investigated in mouse cardiac and skeletal muscles. The concentration of vitamin E decreased 35.8% in 5 weeks and 61.2% in 12 weeks in skeletal muscle. The corresponding decrease in cardiac muscle was 65.7% in 12 weeks. Simultaneously the susceptibility of muscle homogenates to in vitro lipid peroxidation increased with 48.6% (5 weeks) and 44.5% (12 weeks) in skeletal muscle and with 101.8% (12 weeks) in cardiac muscle. Highly significant negative correlations were observed between the concentration of vitamin E and in vitro lipid peroxidation in cardiac and skeletal muscles. Also the sensitivity to Fe2+-induced peroxidation was increased in skeletal muscle after the deficiency of 5 weeks. The total contents of peroxidizable lipids (Fe2+-induction) were significantly (approx. 20%) decreased after 12 weeks in cardiac and skeletal muscles. The concentration of lipofuscin was unaffected in both muscles of vitamin E-deficient mice. Vitamin E deficiency (5 weeks) decreased the activity of selenium-dependent glutathione peroxidase in skeletal muscle but did not affect the activities of catalase and beta-glucuronidase and the concentrations of protein, reduced glutathione and total sulfhydryl groups. These results show that a short-term vitamin E deficiency affects the peroxidative properties of cardiac and skeletal muscles and may thus expose the muscles to peroxidation injuries.

Animals↗
PubMed1984

Transmural distribution of glucose uptake in the rat heart: effects of mechanical work load, substrate supply and exercise.

Glucose uptake is greater in the subendocardial layer of a Langendorff-perfused rat heart than in the subepicardial layer during basal conditions and also under basal conditions in the rat in vivo. The increase of aortic pressure in vitro or physical exercise in vivo causes the disappearance of the transmural gradient in glucose uptake, as does also the elimination of the mechanical work load by potassium induced cardiac arrest. Co-infusion of alternative substrates (oleate, lactate or acetate) causes an overall inhibition of cardiac glucose uptake but does not affect its proportional regional uptake. The left ventricular work load seems thus to be the major determinant of the transmural distribution of the left ventricular glucose uptake. Chronic physical exercise results in the disappearance of the transmural gradient in glucose uptake measured in isolated perfused heart. This redistribution of glucose uptake may reflect differences in the adaptative response of various myocardial layers to a long-term intermittent increase in the cardiac work load.

Animals↗
PubMed1983

Increased prolyl 4-hydroxylase activity in the myocardium of endurance-trained mice.

Endurance training over 3, 10 or 20 days increased the activity of prolyl 4-hydroxylase (PH) in the left ventricle of mice. No increase was observed in the weight of the left ventricle, in galactosylhydroxylysyl glucosyltransferase activity or in hydroxyproline concentration. The increase in PH suggests that the synthesis of collagen increases during physiological adaptation of the heart to endurance exercise without changes in the ventricle weight or its total collagen content.

Animals↗
PubMed1983

Lysosomal and nonlysosomal hydrolases of skeletal muscle in neuromuscular diseases.

The activities of four lysosomal and two nonlysosomal hydrolases were studied in skeletal muscle biopsy samples from patients with neuromuscular diseases and from controls. beta-Glucosaminidase activity was increased in polymyositis. beta-Glucuronidase and alkaline protease activities were elevated in muscular dystrophy in adults, whereas cathepsin D activity was increased in amyotrophic lateral sclerosis. There were significant correlations between the activities of lysosomal and nonlysosomal hydrolases. The activity of beta-glucuronidase, beta-glucosaminidase, alkaline protease, and dipeptidyl aminopeptidase IV showed a positive correlation with the severity of muscular atrophy. The activities of these hydrolases and the activity of dipeptidyl aminopeptidase I correlated positively with the activities of muscular galactosylhydroxylysyl glucosyltransferase and with the serum concentration of type III procollagen aminoterminal propeptide. The results suggest that in neuromuscular diseases the lysosomal and nonlysosomal pathways for muscle degradation are affected concomitantly with collagen biosynthesis.

Adult↗
PubMed1983

Susceptibility of mouse skeletal muscles to exercise injuries.

The susceptibility to exercise-induced myopathy was studied by histological and biochemical methods in various skeletal muscles of mice 3-4 days after a single bout of prolonged running. The degree of exercise injuries varied greatly in different muscles. Soleus and the red deep parts of quadriceps femoris were the most severely affected muscles. Extensive or scattered necrosis of muscle fibers was associated with focal inflammation and a five- to nine-fold increase in the activity of beta-glucuronidase in these muscles. Slight necrotic changes and a two- to three-fold increase in the activity of beta-glucuronidase were observed in tibialis anterior, plantaris, and the red deep parts of gastrocnemius. A statistically significant increase in beta-glucuronidase activity was also observed in the white distal part of quadriceps femoris, biceps femoris, gracilis, extensor digitorum longus, and peroneal muscles but necrotic lesions were infrequent in these muscles. The degree of exercise injuries is probably affected by the different recruitment of muscles during running and by the anatomical location of muscles in separate compartments, which could expose them to different levels of ischemic compression by postexercise edema.

Animals↗
PubMed1983

Increased activities of prolyl 4-hydroxylase and galactosylhydroxylysyl glucosyltransferase, enzymes of collagen biosynthesis, in skeletal muscle of endurance-trained mice.

The activities of prolyl 4-hydroxylase (PH) and galactosylhydroxylysyl glucosyltransferase (GGT), and the concentration of 4-hydroxyproline were measured in red and white parts of quadriceps femoris muscle of mice after 3, 10, and 20 sessions of daily endurance training. The activities of PH and GGT increased in the red part of the muscle after training for 3 and 10 times and returned to the control level after 20 training sessions. In the white muscle the increase of PH activity was less than in the red muscle. No alteration in GGT activity was observed in the white muscle. The concentration of hydroxyproline was unchanged in the both types of skeletal muscle. The results suggest that collagen turnover in leg muscles may be enhanced during the early phase of adaptation to endurance training. The enhancement is more prominent in red than in white skeletal muscle.

Animals↗
PubMed1983

Lipid peroxidation in exercise myopathy.

Selected estimates of lipid peroxidation were analyzed in mouse quadriceps femoris muscle immediately after submaximal prolonged (9 hr) and exhaustive maximal running (2-3 hr), and at intervals 1-10 days afterward during the exercise-induced myopathy. Immediately after the two types of exertion no significant changes were observed in the concentrations of lipid peroxidation products (thiobarbituric acid (TBA) reactive substances, and lipofuscin) or in the estimates of autoxidation (spontaneous and Fe2+-induced autoxidations) and antioxidant (catalase, glutathione peroxidase, and vitamin E) capacities. The enzymatic estimate of exercise myopathy (beta-glucuronidase) increased considerably (2-6 days) after both types of exertion. Simultaneously, the lipid peroxidation rate of muscle homogenates in vitro increased markedly and in highly significant correlation with the activity of beta-glucuronidase. The concentrations of TBA reactants and lipofuscin as well as Fe2+-induced lipid peroxidation were not affected during exercise myopathy. The activities of catalase and glutathione peroxidase increased significantly after both exertions, while the concentration of vitamin E was unchanged. Exhaustive running of endurance-trained mice caused only slight signs of myopathy and no increase in the rate of lipid peroxidation in vitro.

Animals↗
PubMed1983

Exercise myopathy: selectively enhanced proteolytic capacity in rat skeletal muscle after prolonged running.

The proteolytic capacity of rat skeletal muscle was analyzed during the repair of fiber injuries after strenuous exercise. A single bout of prolonged exercise (8 hr running at a speed of 17 m X min-1) caused a slight fiber necrosis and a selective response in the proteolytic activity of rat skeletal muscle. Acid proteolytic capacity (cathepsin D and acid autolysis) was considerably increased on the 4th day after exertion and partially decreased by the 10th day. The acid hydrolytic response was more prominent in red than in white skeletal muscle. Alkaline proteolytic capacity (alkaline and myofibrillar proteases), increased in several atrophic myopathies, was not affected in exercise myopathy. The rate of neutral autolysis slightly increased after exertion. The protein content of skeletal muscle was decreased on the 4th day after exertion. We suggest that the proteolytic responses to acute injuries, as well as to chronic atrophies, are highly selective in skeletal muscle fibers.

Animals↗
PubMed1983

Acid hydrolase activity in tissues of mice after physical stress.

The activities of beta-glucuronidase and cathepsin D and the protein concentration were assayed from brain, kidney, liver, cardiac muscle and skeletal muscle (m. rectus femoris) samples from mice (Mus musculus) 1, 3, and 6 days after intermittent exhaustive (duration 100-145 min) and submaximal prolonged (duration 9 hr) running on treadmill. The activity of beta-glucuronidase in skeletal muscle strongly increased being the highest 3 days after both exertions. Cathepsin D activity also slightly increased. In cardiac muscle beta-glucuronidase activity was unaffected. Cathepsin D activity slightly increased 3 days after intermittent exhaustive exercise. The specific activities of beta-glucuronidase and cathepsin D in the liver increased 1 day after the both exertions. Simultaneously the protein concentration decreased. In the kidney beta-glucuronidase activity and protein concentration were unaffected but cathepsin D activity decreased 1 day after intermittent exhaustive exercise. In the brain protein concentration transiently decreased 3 days after the exertions. beta-Glucuronidase activity transiently decreased 1 day after intermittent exercise thereafter increasing 6 days afterwards above the control level. Cathepsin D activity decreased 1 day after intermittent exercise but was unaffected after prolonged submaximal exercise. Physical stress affected to varying extent the acid hydrolase activities in all organs studied.

Animals↗
PubMed1983

Changes in lysosomal enzyme activities in exercise-induced cardiac hypertrophy of mice.

The activities of several lysosomal enzymes were assayed in control and in exercise-hypertrophied cardiac muscle of mice (Mus musculus). The repeated running program increased the activity of beta-glucuronidase (16.1%) in mouse cardiac muscle. Decreased activities of beta-N-acetylglucosaminidase (10.8%), acid ribonuclease (10.7%), and arylsulphatase (14.2%) were observed in the hypertrophied myocardium. The activities of acid deoxyribonuclease, cathepsin C, cathepsin D, and p-nitrophenylphosphatase as well as the activities of citrate synthase and cytochrome c oxidase, mitochondrial enzymes, were unaffected in cardiac muscle. We suggest that lysosomal enzyme responses are selective and highly different in physiologically and pathologically induced cardiac hypertrophies.

Acetylglucosaminidase↗
PubMed1983

Endurance training reduces the susceptibility of mouse skeletal muscle to lipid peroxidation in vitro.

Selected estimates of the lipid peroxidative capacity were assayed in the red and white skeletal muscles of control and endurance-trained mice. Endurance training decreased the lipid peroxidation rate in vitro in both muscle types. The concentration of lipids susceptible to Fe2+-induced lipid peroxidation was greater in the red than in the white skeletal muscle and increased after endurance training in the red muscle. Endurance training, however, decreased highly significantly the sensitivity of red muscle to in vitro stimulated lipid peroxidation. The activity of catalase and the concentration of vitamin E were considerably higher in the red muscle, whereas the activity of glutathione peroxidase was slightly higher in the white muscle. Endurance training caused no changes in these antioxidants. Endurance training increased the concentrations of reduced and total non-protein glutathione in the red skeletal muscle but not in the white muscle. The total sulfhydryl group contents were unaffected. Our results suggest that endurance training may increase the resistance of skeletal muscle to injuries caused by lipid peroxidation.

Animals↗
PubMed1983

Effects of endurance training on alkaline protease activities in rat skeletal muscles.

This study aimed at comparing the effects of running and swimming training protocols and the termination of training on the activities of two proteases with alkaline pH-optima (alkaline protease and myofibrillar protease) in the tibialis anterior, soleus, and gastrocnemius muscles of male rats. The training on treadmill decreased the activities of alkaline and myofibrillar proteases by approx. 10-20% in the muscles studied. The activities of both proteases were unchanged in swimming-trained rats. Two weeks after the termination of running training the activity of alkaline protease was increased in gastrocnemius muscle but not in the other muscles. Swimming training increased the activity of citrate synthase in all muscles studied but training by running only in the soleus muscle. The running protocol increased the activity of beta-glucuronidase in the tibialis anterior muscle and decreased the activity in the gastrocnemius muscle. The swimming program did not affect beta-glucuronidase activities. These results show diverse effects of running and swimming training on alkaline proteolytic activities as well as on mitochondrial and lysosomal marker enzymes.

Animals↗