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Biomedical subjects

V Vihko

Publications and source records attributed to V Vihko.

At least 73 records · Page 4Linked to original sources
PubMed1982

Changes of dipeptidyl aminopeptidase activities in mouse skeletal muscle following prolonged running.

1. Activities of dipeptidyl aminopeptidases (DAP), leucine arylamidase and beta-glucuronidase were assayed in red and white parts of mouse quandriceps femoris muscle 3 and 7 days after a single bout of prolonged running. 2. The activities of lysosomal acid hydrolases (DAP I, DAP II and beta-glucuronidase) were highly increased on the 3rd day after the exertion and then decreased by the 7th day. The response was more prominent in red than in white skeletal muscle. 3. The activities of two microsomal hydrolases, DAP IV and leucine arylamidase, increased much less than those of the lysosomal acid hydrolases. The highest activities were recorded on the 7th day after exertion. 4. The activity of DAP III, a cytoplasmic peptidase, was unaffected in red muscle but slightly increased in white muscle. 5. The protein content of red skeletal muscle, but not that of white muscle, decreased transiently after the running. 6. It seems that strenuous exercise selectively stimulates the lysosomal proteolytic system in skeletal muscle, while the others are less affected.

Animals↗
PubMed1981

Acid hydrolase activities in mouse cardiac and skeletal muscle following exhaustive exercise.

Acid hydrolase activities in skeletal and cardiac muscle were studied 5, 10 and 20 days after exhaustive intermittent running by untrained and endurance-trained mice. Exhaustion increased the activities of cathepsin D, beta-glucuronidase and ribonuclease, but not that of p-nitrophenylphosphatase in skeletal muscle of untrained mice. Activities were highest on the fifth day after exhaustion and decreased during the following two weeks. More intensive loading produced no changes in acid hydrolytic capacity in skeletal muscle of endurance-trained mice. Acid hydrolase activities in cardiac muscle of both untrained and trained mice were unaffected by exhaustive running. It is suggested that exhaustive running causes both lethal and sublethal hypoxic fiber injuries in the skeletal muscle of untrained mice but not in that of endurance-trained mice or in the cardiac muscle of animals of either group. These injuries manifest themselves as fiber necrosis (lethal) and as increased acid hydrolytic capacity in surviving fibers (sublethal).

Animals↗
PubMed1981

Effects of age and prolonged running on proteolytic capacity in mouse cardiac and skeletal muscles.

Male NMRI-mice, aged 3, 6, 9, and 12 months, were made to run for a period of 4 4 at a speed of 13.5 m/min on a motor-driven treadmill, 5 days after exertion, selected enzymatic estimates of acid and alkaline proteolytic as well as energy metabolic capacities were analyzed from the cardiac muscle and from the red and white parts of m. quadriceps femoris (MQF). The activities of alkaline and myofibrillar proteases increased most considerably in skeletal muscles with age. Cathepsin D and beta-glucuronidase activities were less affected in both muscles. Prolonged running increased the activities of cathepsin D, dipeptidyl aminopeptidase I and beta-glucuronidase in the white and, especially in the red part of MQF. This stimulation of acid hydrolytic capacity was more prominent at the ages of 3 and 6 months than in the older animals. The estimates of alkaline proteolytic or energy metabolic capacities were not affected by prolonged running. In cardiac muscle, no significant changes were recorded in acid hydrolytic or energy metabolic capacity. Histological observation showed no necrosis or other pathological phenomena in the proximal part of m. rectus femoris after excretion. We suggest that the increased acid proteolytic capacity is involved in subcellular regenerative processes of skeletal muscle fibres. The smaller lysosomal response of older mice may indicate a reduced potential capacity for cellular repair.

Aging↗
PubMed1980

Lipid metabolism during exercise. II. Respiratory exchange ratio and muscle glycogen content during 4 h bicycle ergometry in two groups of healthy men.

Seven physically fit (well-trained, maximal oxygen uptake 69.6 +/- 4.4 ml x kg-1 min-1) and eight less fit (moderately trained, maximal oxygen uptake 56.1 +/- 5.7 ml x kg-1 x min-1) healthy male subjects were exercised for 4 h by bicycle ergometry against a pedalling resistance calculated to cause oxygen consumption corresponding to approximately 30% of each individual's maximal oxygen uptake value. Respiratory exchange ratio was estimated at 1 h and blood glucose and lactate concentrations and muscle glycogen content at 2 h intervals. Muscle glycogen content decreased markedly during the first 2 h of exercise in the well-trained group but was similar after 4 h exercise in both groups. No major differences were observed between the two subject groups in blood variable concentrations. Calculations based on respiratory exchange ratio showed that the proportion of carbohydrates utilized in the total energy consumption was 14% in the physically fit group and 25% in the less fit group, thus supporting previous observations that more energy is derived by fat oxidation in well-trained than in less-trained individuals during submaximal work at relatively similar oxygen consumption levels.

Blood Glucose↗
PubMed1980

Acid proteolytic capacity in mouse cardiac and skeletal muscles after prolonged submaximal exercise.

Acid proteolytic capacity in mouse cardiac muscle and in predominantly white (distal head of m. vastus lateralis) or predominantly red (proximal red heads of m. vastus lateralis, m. v. medialis, and m. v. intermedius) skeletal muscle was estimated 5 days after 3 h, 6 h or 9 h prolonged running at a speed of 13.5 m/min. The activities of acid protease and beta-glucuronidase together with the rate of acid autolysis considerably increased in both skeletal muscle types, especially in red muscle, but did not increase in cardiac muscle. Acid proteolytic capacity and beta-glucuronidase activity increased in relation to the duration of running. Protein content and oxidative capacity (the activities of citrate synthase and malate dehydrogenase) decreased in red skeletal muscle after 6 h and 9 h running. In white muscle only protein content slightly decreased after 9 h running. No corresponding changes were observed in cardiac muscle. Histopathological changes were traced in mixed skeletal muscle (m. rectus femoris). Necrotic lesions were observed in the red superficial area of m. rectus femoris after 6 h and, in particular, after 9 h running. The results show that prolonged submaximal running also produces lethal and sublethal skeletal muscle fibre injuries, as well as exhaustive exercise or temporary ischaemia as reported earlier. It is suggested that sublethal injuries precede lethal ones and that acid proteolytic capacity increases especially in the sublethally injured muscle fibres.

Animals↗
PubMed1979

Morphometry of myocardial apex in endurance-trained mice of different ages.

Mitochondrial volume density, surface density of the outer mitochondrial membrane, the mean number and size of mitochondria, and the mean surface density of crista membranes together with the volume densities of myofibrils and sarcoplasmic space were morphometrically analyzed in cardiac muscle of two groups of sedentary control mice aged 3 and 7 months, and in two groups of mice trained either 1 month rather intensely or 4 months moderately. Of the calculated mitochondrial variables only the surface density of the outer mitochondrial membrane differed between the older controls and the older trained animals, the density being slightly smaller in the trained group. The myofibrillar volume density of the order controls was smaller than that of the younger controls, while the sarcoplasmic volume density was larger. The latter difference, possibly a function of age, was also observed in the trained groups. The results suggest that at a certain steady state level of exercise-induced cardiac muscle hypertrophy the muscle cells of trained mice do not differ markedly in ultrastructural properties from those of sedentary controls.

Age Factors↗
PubMed1979

Exhaustive exercise, endurance training, and acid hydrolase activity in skeletal muscle.

The activity of eight acid hydrolases and two energy metabolism enzymes were assayed from homogenates of predominantly red (proximal heads of m. vastus lateralis, m. vastus medialis, and m. vastus intermedius) and predominantly white (distal head of m. vastus lateralis) skeletal muscle of mice belonging to one of the following groups: 1) sedentary controls, never trained or exhausted; 2) exhausted controls, exhausted once by running on a treadmill 5, 10, or 20 days before killing; 3) trained mice, exercising until killed; 4) exhausted trained mice, exercising until exhausted 5, 10 or 20 days before killing, not exercising during that period; and 5) detrained mice, terminating training 5, 10, or 20 days before killing. In untrained but not in trained animals, exhaustive exercise caused, 5 days afterward, fiber necrosis and a marked increase in the activities of beta-glucuronidase, beta-N-acetylglucosaminidase, arylsulphatase, ribonuclease, deoxyribonuclease, cathepsin D, and cathepsin C, especially in red muscle fibers. Training increased the activities of citrate synthase, beta-glucuronidase, and cathepsin D in both muscle types and those of beta-N-acetylglucosaminidase, arylsulphatase, and cathepsin C in red muscle. Effects of detraining were minor. Exhaustive exercise causes lethal and evidently also sublethal fiber injuries manifesting themselves as an activation of the lysosomal system of muscle fibers 5 days later. Training affects cellular homeostasis by causing an apparent resistance to the damaging effects of exhaustive exercise. Moderately increased hydrolase activities may reflect increased turnover in endurance-trained muscles.

4-Nitrophenylphosphatase↗
PubMed1978

Acid hydrolase activity in red and white skeletal muscle of mice during a two-week period following exhausting exercise.

The activities of beta-glucuronidase, beta-N-acetylglucosaminidase, arylsulphatase, ribonuclease, p-nitrophenylphosphatase, and malate dehydrogenase together with protein content were assayed from representative mixed (m. rectus femoris), predominantly red (proximal heads of m. vastus lateralis, m.v. medius and m. v. intermedius), and predominantly white (distal head of m. vastus lateralis) muscle homogenates of mice during a two-week period following one single exposure to exhausting intermittent running on a treadmill. The activities of cathepsin D and beta-glycerophosphatase were assayed from mixed muscle only. In all three muscle types, particularly in red muscle, the activities of beta-glucuronidase, beta-N-acetylglucosaminidase, arylsulphatase, and ribonuclease progressively increased between one to five days after the exercise; thereafter the activities began to decrease, being near the conrol values 15 days after the exercise. In mixed muscle, cathepsin D activity increased. No corresponding changes were observed in the activities of acid phosphatases. The time course of the activity changes closely resembled that earlier found to be caused by ischaemia in rabbit muscles. It is tentatively concluded that the two treatments, exhaustive exercise and temporary ischaemia, cause similar cell injuries, and that the lysosomal system involved seems to function similarly in the post-stress recovery of the fibres from these injuries.

4-Nitrophenylphosphatase↗
PubMed1978

Effect of isometric strength training of mechanical, electrical, and metabolic aspects of muscle function.

Monozygous twin pairs (two female and four male) were used in a strength training study so that one member of each pair served as training subject (TS) and the other members as nonexercising controls (CS). TS trained four times a week for 12 weeks with maximal isometric knee extensions of the right leg. The parameters studied included muscle strength, endurance time, electromyographic activity, and activities of several key enzymes in nonoxidative an oxidative muscle metabolism. The results disclosed that in addition to a 20% increase in isometric knee extension strength in the trained leg of TS, an average increase of 11% was observed in strength of TS untrained leg. CS did not demonstrate any change in muscle strength. Training also included an improvement in the maintenance of a static load of 60% of the pretraining maximum. Increase in the maximum integrated electromyographic activity (IEMG) of the rectus femoris muscle occurred concomitantly with the knee extension strength. Traning also caused reduction in the IEMG/tension ratio at submaximal loads indicating a more econimical usage of the rectus femoris muscles. Muscle biopsies taken from the vastus lateralis muscle showed that the enzyme activities of MDH, SDH, and HK were higher, and LDH and CPK lower in the trained leg as compared to the nontrained control leg of TS or to the values of the untrained member of the twin pair. It is concluded that isometric strength training as used in the present study can cause increased recruitment of the availabel motor unit pool, improved efficiency at submaximal loads, and surprisingly also enchancement of the oxidative metabolism in the muscle.

Adolescent↗
PubMed1978

beta-Glucuronidase activity in trained red and white skeletal muscle of mice.

We studied the effects of prolonged running exercise (5 days a week, 1.5 h per day at a speed of 17.6 m/min) on the activity of some acid hydrolases (beta-glucuronidase, beta-N-acetylglucosaminidase, acid phosphatase and cathepsin D) and three enzymes of energy metabolism (cytochrome c oxidase, lactate dehydrogenase and creatine kinase) in the distal and in the proximal, the predominantly white and red parts, respectively, of the vastus lateralis-muscle from mice. The acid hydrolase activity levels were 1.24--1.69 higher in untrained red muscle compared to untrained white muscle. The light training applied increased the activity of beta-glucuronidase in both red and white muscle. No other significant training effects were observed in the enzyme activities measured.

Acetylglucosaminidase↗
PubMed1978

Exhaustive physical exercise and acid hydrolase activity in mouse skeletal muscle. A histochemical study.

Adult, untrained NMRI mice were exhausted on a motor-driven treadmill by an intermittent-type running programme. Serial cryostate sections for the staining of NADH-tetrazolium reductase, beta-glucuronidase, beta-N-acetylglucosaminidase, and beta-glycerophosphatase activities and for making hematoxylin-eosin staining were cut from m. quadriceps femoris 1, 2, 3, 5, 7, and 15 days after physical exhaustion. A strong increase in the activities of beta-glucuronidase and beta-N-acetylglucosaminidase was observed 7 days after exhaustion and the activity changes, which were similar for the both glycosidases, were more prominent in the highly oxidative red compared to less oxidative white fibres. Activity granules were more numerous in the perinuclear than the interfibrillar area of red fibres. Spots were arranged like longitudinal chains between myofibrils. Activity in connective tissue was usually observed only in animals exhausted 3--7 days earlier. Simultaneous activity in fibres exceeded that in connective tissue. beta-Glycerophosphatase activity was not, by the method used, seen in histologically "healthy" or normal-looking fibres. In samples taken 2--5 days after exhaustion some degenerating and necrotic fibres were observed. Inflammatory reaction was also observed being at its strongest five days after loading when mononuclear cells were seen inside necrotic fibres. The number of regenerating muscle cells was most abundant 7 days after exhaustion. It is suggested that temporary hypoxia, which accompanies exhaustive physical exercise in skeletal muscle, upsets the energy metabolism and homeostasis of fibres and causes the observed histological and histochemical alterations, which possess features typical of both lethal and sublethal acute cell injury.

Acetylglucosaminidase↗
PubMed1978

Oxidative and lysosomal capacity in skeletal muscle of mice after endurance training of different intensities.

The activity of certain enzymes of energy metabolism (cytochrome c oxidase, citrate synthase, malate dehydrogenase, and lactate dehydrogenase) and of lysosomes (beta-glucuronidase, beta-N-acetylglucosamindase, arylsuphatase, ribonuclease, deoxyribonuclease, acid phosphatase, and cathepsin D) was assayed from m. rectus femoris of mice trained 5 days per week, 1 hr per day for 4 weeks according to 4 different programmes: I. running speed 20 m/min, horizontal track, II. 25 m/min, horizontal track, III. 20 m/min 8 degrees uphill inclination, and IV. 25 m/min 8 degrees uphill inclination. Oxidative capacity increased and anaerobic capacity decreased without distinction between the different traning programmes. Of acid hydrolases assayed the activities of beta-glucuronidase and cathepsin D were increased independently of training intensity. Simultaneous histochemical observations on beta-glucuronidase and arylsulphatase activities in the contralateral m. rectus femoris showed more intense staining in red as compared to white muscle fibres. It is suggested that training affected the red fibres and that the applied level of loading was probably too low to cause major involvement of white fibres.

Acetylglucosaminidase↗
PubMed1978

Activity of acid hydrolases in skeletal muscle of untrained, trained and detrained mice of different ages.

The activities of p-nitrophenylphosphatase, beta-glucuronidase and beta-N-acetylglucosaminidase from crude skeletal muscle homogenates of 4 and 7 months old mice were assayed after short-term intensive and long-term moderate training and after terminated training. In the older untrained mice the activity of the hydrolases was higher than in the younger mice. The level increased with training and this increase was far more pronounced in the older animals. Cessation of training for 7 and 21 days decreased this activity in the older animals but it was again increased 42 days later and close to the level observed in the trained mice. In young mice 3 days' terminated training increased the activity of the acid hydrolases above the level of the trained animals but after additional 4 and 11 days' terminated training the activity decreased to slightly below that of the trained mice. The changes were most prominent in the activity of beta-glucuronidase and to a lesser extent in that of beta-N-acetylglucosaminidase while p-nitrophenylphosphatase activity was almost unaffected by training or terminated training. The effects of terminated training can be intepreted as representing altered catabolic processes in the turn-over of tissue components of skeletal muscle.

4-Nitrophenylphosphatase↗
PubMed1977

Anaerobic performance capacity in athletes.

Anaerobic performance characteristics of the whole body and at muscle tissue level were studied in 89 athletes and 31 reference subjects. The main parameters were vertical velocity during running up the stairs, maximal isometric force of leg extensor muscles, blood lactate concentration after maximal treadmill running test, percentage of fast twitch muscle fibers (% FT fibers), lactate dehydrogenase (LDH) and creatine phosphokinase (CPK) activity in vastus lateralis muscle. These parameters tended to divide the athletes and their sport events into neuromuscular, anaerobic and aerobic types. The specific needs of the different sport events might have masked the expected characteristics of energy and power utilization. However, a high percentage of FT fibers might be a prerequisite for a successful athlete in certain neuromuscular-anaerobic type events ("power events"). The main parameters describing the anaerobic performance capacity of the whole body (vertical velocity, leg force, blood lactate) were found to be related to muscle fiber composition (% FT fibers). The running velocity rather than muscle strength seemed to be more influenced by activity of enzymes LDH and CPK.

Adult↗
PubMed1977

Effect of endurance training on the capacity of red and white skeletal muscle of mouse to oxidize carboxyl-14C-labelled palmitate.

Three groups of mice were trained for 1, 4 and 5 months according to different running programs on a motor driven treadmill and the fatty acid oxidation capacity (FAO) and the activities of some enzymes of energy metabolism (cytochrome c oxidase, malate dehydrogenase, triosephosphate dehydrogenase, and lactate dehydrogenase) were determined from m. quadriceps femoris (MQF). Endurance training increased the FAO [5-month training 4 days/week, 30 min/day 22% (p less than 0.05); 1-month training, 7 days/week, 150 min/day 37% (p less than 0.001); 4-month training, 5 days/week, 60 min/day 24% (p less than 0.05)]. The activities of cytochrome c oxidase and malate dehydrogenase increased approx. 30% (p less than 0.001) whereas triosephosphate dehydrogenase and lactate dehydrogenase activities were not prominently influenced by training. The predominantly red part of MQF of untrained animals oxidized palmitate four times faster than the predominantly white part. The activities of cytochrome c oxidase and malate dehydrogenase were two times higher showing pronounced FAO in the red part. Endurance training increased the FAO and activities of oxidative enzymes in the red and white parts and in the whole muscle relatively equally resulting in similar differences between the muscle types after training. The absolute increase in the FAO of the red muscle was, however, manyfold when compared in chemical units to the white muscle.

Animals↗