Isoenzyme profile of lactate dehydrogenase in the cranial cervical sympathetic ganglion under normal conditions and during synaptic blockade

The isoenzyme profile of lactate dehydrogenase in the cranial cervical sympathetic ganglion of rabbits was studied under normal conditions and during blockade of nicotinic cholinergic synapses. Under normal conditions this profile was presented by 5 isoforms of the enzyme (lactate dehydrogenases 1, 2, 3, 4, and 5). Activity of H-isoforms prevailed. Blockade was accompanied by heterotropic allosteric inhibition of lactate dehydrogenase isoforms. H-and M-isoforms underwent simultaneous changes. Activity of H-isoforms sharply decreased. However, the ratio between lactate dehydrogenases 1 and 2 during complete or partial blockade did not differ from that observed in experiments with the intact ganglion. M-isoforms (lactate dehydrogenases 4 and 5) disappeared during partial blockade. Activity of hybrid lactate dehydrogenase 3 significantly decreased and was undetected during partial and complete blockade, respectively. Our results indicate that enzyme activity and isoenzyme profile of lactate dehydrogenase are determined by function of nicotinic synapses. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 140, No. 12, pp. 642–644, December, 2005     

Effect of lactate on functional activity of macrophages under normal conditions and during tumor growth

Lactate modulated functional activity of macrophages from intact mice and animals with transplantable syngeneic hepatoma 22a. Sodium lactate in a concentration of 6.5 mM in vitro increased functional activity of resident peritoneal macrophages from intact mice. The growth of transplantable syngeneic hepatoma 22a was associated with the absence of correlation between nitrite synthesis by peritoneal macrophages and serum lactate concentration. Therefore, this agent cannot be considered as a systemic activator of macrophages. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 141, No. 1, pp. 72–75, January, 2006     

The influence of muscle metabolic characteristics on physical performance

Summary This study describes the influence of muscle fiber type composition, enzyme activities and capillary supply on muscle strength, local muscle endurance or aerobic power and capacity. Muscle biopsies were obtained from m. vastus lateralis in thirteen physically active men. Histochemical staining procedures were applied to assess the percentage of fast twitch (FT) fibers, muscle fiber area, and capillary density. Also, the activity of citrate synthase (CS), creatine kinase (CK), hexokinase (HK), lactate dehydrogenase (LDH), and phosphofructokinase (PFK) were analysed using fluorometrical assays. Peak torque at ‘low’ and ‘high’ angular velocities was measured during leg extension. Similarly, muscle fatigue (e. g. peak torque decline) and recovery from a short-term exercise task were measured during maximal, voluntary consecutive leg extensions. Aerobic power ( ) and aerobic capacity (e.g. onset of blood lactate concentration; OBLA), as defined by a blood lactate concentration of 4 mol · l⁻¹ were measured during cycling. Peak torque at a high angular velocity was positively correlated with % FT area (p<0.001). Fatigue and recovery were correlated with LDH · CS⁻¹ (p<0.001). W_OBLA was best correlated with PFK and PFK · CS⁻¹ (p<0.001). Hence, muscle strength was partly determined by fiber type composition whereas local muscle endurance, recovery and aerobic capacity reflect mainly capillary supply and the activity of key enzymes involved in aerobic and anaerobic metabolism.     

No difference in net uptake or disposal of lactate by trained and untrained forearms during incremental sodium lactate infusion

A number of training adaptations in skeletal muscle might be expected to enhance lactate extraction during hyperlactataemia. The aim of the present study was to determine whether resting endurance-trained forearms exhibit an increased net lactate removal during hyperlactataemia. Six racquet-sport players attended the laboratory for two experiments, separated by 2 weeks. In the first experiment incremental handgrip exercise to fatigue was performed to identify trained (TRFA, n=6) and untrained (UTFA, n=5) forearms. In the second experiment net forearm lactate exchange was compared between TRFA and UTFA during an incremental infusion of sodium lactate. TRFA performed more work than UTFA during handgrip exercise [mean (SE) TRFA, 66.1 (9.5) J·100 ml^–1; UTFA, 35.1 (2.3) J·100 ml^–1; P=0.02] and UTFA exhibited a greater increase in net lactate output relative to work load (P=0.003). During lactate infusion net lactate uptake across the resting forearms increased linearly with the arterial lactate concentration in both groups (TRFA, r=–0.95 (0.03); UTFA, r=–0.92 (0.04); P<0.02], with no difference in the regression slopes [TRFA, –1.06 (0.13); UTFA, –1.07 (0.27); P=0.97] or y-intercepts [TRFA, 0.67 (0.20); UTFA, 1.36 (0.67); P=0.37] between groups. Almost all of the lactate taken up was disposed of by both groups of forearms [TRFA, 99.6 (0.2)%; UTFA, 98.5 (1.0)%; P=0.37]. It was concluded that the net uptake and removal of lactate by resting skeletal muscle is a function of the concentration of lactate in the blood perfusing the muscle rather than the muscle training status. Electronic Publication     

Efficiency of trekrezan in experimental bronchopneumonia in rats

Trekrezan in a dose of 25 mg/kg normalized the lymphocyte immune status and produced an energy-stabilizing effect, which manifested in decreased levels of lactate, ADP, and AMP and increased content of pyruvate and ATP in blood lymphocytes and lung tissue of rats with experimental acute bronchopneumonia. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 142, No. 8, pp. 170–173, August, 2006     

Effect of cold water immersion on 100-m sprint performance in well-trained swimmers

The aim of the present study was to examine the effect of cold water immersion (CWI) on sprint swimming performance in simulated competition conditions. Ten well-trained swimmers (5 males, 5 females; 19.0 ± 3.9 years) performed two 100-m swimming sprints (S1 and S2) interspersed with a 30-min passive recovery period, during which athletes were randomly assigned to 5 min of CWI (14°C) or an out-of-water control condition (CON 28°C). During tests, sprint times, heart rate (HR), pre- and post-race parasympathetic activity via HR variability (natural logarithm of the square root of the mean of the sum of the squares of differences between adjacent normal R–R intervals; Ln rMSSD) and blood lactate accumulation ([La]_ac) and clearance ([La]_cle) were recorded. Rates of perceived recovery (RPR) and exertion (RPE) were evaluated before and after each sprint. CWI was associated with a ‘likely’ decrease in swimming performance [1.8% (90% CI 0.2, 3.5)], as well as ‘likely’ lower peak HR [−1.9% (−3.6, −0.2)]. CWI was also associated with a ‘likely’ smaller decrease in Ln rMSSD after the first sprint [−16.7% (−30.9, −4.1)]. RPR was ‘likely’ better [+27.2% (−3.7, 68.0)] following CWI. ‘unclear’ effects were observed for [La]_ac [+24.7% (−13.4, 79.5)], [La]_cle [−7.6% (−24.2, 12.7)] or RPE [+2.0% (−12.3, 18.5)]. Following CWI, changes in sprint times were ‘largely’ correlated with changes in peak HR (r = 0.80). Despite a subjective perception of improved recovery following CWI, this recovery intervention resulted in slower swimming times in well-trained athletes swimming in simulated competition conditions.     

Effects of compression stockings during exercise and recovery on blood lactate kinetics

This study aimed to investigate if wearing compression stockings (CS) during exercise and recovery could affect lactate profile in sportsmen. Eight young healthy trained male subjects performed two maximal exercise tests on a cycle ergometer on two different occasions performed randomly: CS during both exercise and recovery, and no CS. Blood lactate concentration was taken during exercise and at 0, 3, 5, 10, 15, 30 and 60 min post-exercise. The individual blood lactate recovery curves were fitted to a biexponential time function: \textLa_(t) = \textLa₍₀₎ + A ₁ ( 1- \texte ^{- g₁ t} ) + A ₂ ( 1- \texte ^{- g₂ t} ) {\text{La}}_{(t)} = {\text{La}}_{(0)} + A_{ 1} ( 1- {\text{e}}^{{ - \gamma_{1} t}} ) + A_{ 2} ( 1- {\text{e}}^{{ - \gamma_{2} t}} ) , where γ ₁ and γ ₂ denote the abilities to exchange lactate between the previously active muscles and the blood and to remove lactate from the organism, respectively. A significantly higher blood lactate value at the end of the maximal exercise was found (12.1 ± 0.5 vs. 10.8 ± 0.5 mmol l⁻¹) wearing CS as compared to no CS (P < 0.05). Lower γ ₁ and higher γ ₂ values were observed with CS during recovery, as compared to no CS. It was concluded that CS during graded exercise leads to a significant higher blood lactate value at exhaustion. Since lactate exchanges were expected to be decreased during exercise due to CS, this result was likely attributable to a higher lactate accumulation related to a greater overall contribution of anaerobic glycolysis. Although the lactate removal ability was significantly improved when wearing CS during recovery, its efficacy in promoting blood lactate clearance after high-intensity exercise is limited.     

Comparison of physiological response to cardiopulmonary exercise testing among cancer survivors and healthy controls

Selected physiological responses, including lactate kinetics, to cardiopulmonary exercise testing (CPET) were evaluated among a group of cancer survivors (CS, n = 55) and healthy controls (HC, n = 213). It was uncertain if lactate testing in a group of cancer survivors could provide useful information about training intensity. It was hypothesized that chemotherapy, radiation, surgery, physical inactivity or some combination thereof would alter the normal lactate kinetics (curvilinearity) in the relationship of lactate concentration versus power. Physiologic responses of CS (heart rate, blood pressure, O₂ saturation, RPE, lactate, VO_2peak, and peak power) during cycle ergometry were compared to HC. Comparisons (t tests and Chi-square) were made between the groups and shape of lactate plots were analyzed for determination of a breakpoint. Multiple logistical regressions were then utilized to identify factors related to the inability to determine lactate breakpoints. Lactate breakpoints were common to all but one HC whereas among the CS there was a small subset of subjects (n = 5) who did not show a lactate breakpoint. Group differences indicated that female CS were significantly older, had greater BMI’s, and lower work capacity than HC. Males CS had significantly lower work capacity than HC. Multiple logistical regression analyses, in all instances, yielded no statistically significant models predictive of the inability to determine a lactate breakpoint. In this sample of CS and HC, physiological responses and lactate kinetics during CPET were similar while work capacity among the CS was lower. Because lactate breakpoints were found, lactate threshold could be determined for all but a few individuals. For those working with CS, CPET with ECG monitoring and lactate threshold measures should be considered for those wishing for precise and safe training intensities.     

Effect of acute hypobaric hypoxia on spermatogenesis and lactate concentration in testicular tissue of male albino rats

Parameters of spermatogenesis in male albino rats was studied after experimental acute hypobaric hypoxia. The number of spermatogenic epithelial cells, Sertoli cells, and Leydig cells in testicular tissue significantly decreased in the posthypoxic period. Single exposure to hypoxia led to significant changes in lactate concentration in the testicular tissue. Cell composition of the testicles did not return to normal by the 60th day after treatment. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 141, No. 1, pp. 24–26, January, 2006     

Biorhythms of activities of liver and blood dehydrogenases and changes in body weight of the rats feeding normal diet or excess of sugar substitutes

Biorhythms with higher levels of activity of sorbitol dehydrogenase and lactate dehydrogenase in blood plasma, specific activity of sorbitol dehydrogenase, lactate dehydrogenase, and malate dehydrogenase in the liver, and body weight of rats were more pronounced in the spring-summer period than in the autumn-winter period. These specific features were revealed in animals feeding a normal diet or food with 54 and 27% sugar substitute sorbitol. However, specific activity of glucose-6-phosphate dehydrogenase in the liver was higher in the autumn-winter period. Activity of sorbitol dehydrogenase in blood plasma increased by tens of times due to induction of sorbitol synthesis (substrate) in the liver. Sugar substitute xylitol is structurally similar to sorbitol, but is not the substrate for sorbitol dehydrogenase. However, the effect of xylitol on activities of lactate dehydrogenase, malate dehydrogenase, and glucose-6-phosphate dehydrogenase in the spring-summer period was similar to that of sorbitol. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 144, No. 12, pp. 686–689, December, 2007     

Possible involvement of lactate in neuroglial interaction through nicotinic cholinergic synapses in the cranial cervical sympathetic ganglion

Activities of LDH and its H-and M-isoforms in neurons and satellite gliocytes of the cranial cervical sympathetic ganglion in rabbits under normal conditions and during nicotinic cholinergic synapse blockade were evaluated by integral cytophotometry in tissue sections. Normally activity of H-isoform predominates in neurons and M-isoform in satellite gliocytes. Blockade of the cranial cervical sympathetic ganglion significantly decreased LDH activity (H-and M-isoforms) in neurons in direct proportion to the number of blocked nicotinic cholinergic receptors. Activity of M-isoform in satellite gliocytes decreased with increasing the degree of blockade, while activity of H-isoform did not change. The isoenzyme profile of LDH in satellite gliocytes reached the level of intact neurons. Presumably, lactate production in satellite gliocytes is regulated by sympathetic neurons through nicotinic cholinergic synapses. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 142, No. 11, pp. 573–575, November, 2006     

Group- and individual-level coincidence of the ‘Fatmax’ and lactate accumulation in adolescents

Fatmax and lactate increase above baseline (LIAB) were measured in 11 adolescent girls and 8 adolescent boys during incremental cycling. Fatmax was the exercise intensity at the point of maximal fat oxidation rate (MFO). The LIAB was the exercise intensity coincident with a sustained increase in blood (lactate) above an initial baseline. We defined the minimum important difference (MID) between the exercise intensity at Fatmax and LIAB as ±8% of both peak [(V)\dot]\textO₂ {\dot{V}}{\text{O}}_{2} and peak heart rate (HR). Systematic bias was examined via the mean difference between parameters and its uncertainty, with inference based on the disposition of the confidence interval to the MID. Individual-level agreement was the proportion of differences between Fatmax and LIAB falling within the MID. MFO was at 35 (6)% peak [(V)\dot]\textO₂ {\dot{V}}{\text{O}}_{2} with LIAB at 39 (7)% peak [(V)\dot]\textO₂. {\dot{V}}{\text{O}}_{2}. Systematic bias was −3.8% of peak [(V)\dot]\textO₂ {\dot{V}}{\text{O}}_{2} and −4.4% of peak HR. The estimated population proportion with between-variable agreement within ±8% was 0.76 for both % peak [(V)\dot]\textO₂ {\dot{V}}{\text{O}}_{2} and % peak HR. Within the tolerance limits of the MID, the mean bias is ‘almost certainly not’ important; similarly, there is good agreement between the two parameters at the individual level. We conclude that Fatmax and lactate increase above baseline coincide in adolescents.     

Effect of recombinant interleukin-5, interleukin-3, and eotaxin on apoptosis in eosinophilic granulocytes

We studied in vitro effects of recombinant interleukin-5, interleukin-3, and eotaxin on programmed death of eosinophils from healthy donors and patients with non-Hodgkin’s lymphomas associated with severe blood eosinophilia. Interleukin-5 and eotaxin produced the most potent antiapoptotic effect on eosinophils from healthy donors. In patients with non-Hodgkin’s lymphomas, spontaneous apoptosis in eosinophilic leukocytes was low and remained unchanged during incubation with recombinant proteins. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 143, No. 4, pp. 370–373, April, 2007     

Effect of altered pre-exercise carbohydrate availability on selection and perception of effort during prolonged cycling

This study assessed the effect of altered carbohydrate (CHO) availability on self-selected work rate during prolonged time-trial cycling. Eight endurance-trained men undertook two experimental cycling time-trials after glycogen-depleting exercise and 2 days of: (a) high (9.3 ± 0 g CHO kg⁻¹ day⁻¹) (HC) and (b) low CHO intakes (0.6 ± 0.1 g CHO kg⁻¹ day⁻¹) (LC), via a double-blinded crossover design. All feedback regarding performance was removed during both exercise trials. Self-selected external power output was not different during the first 2 h of exercise between experimental conditions (P > 0.05), despite reported sensations of increased tiredness before and during exercise, significantly reduced whole body CHO oxidation (P < 0.05), plasma lactate concentrations (P < 0.05) and earlier onset of fatigue during exercise in LC versus HC. Perceived exertion was not different throughout exercise between conditions (P > 0.05). Mean power output declined significantly in LC versus HC (P < 0.05) after ∼ 2 h of exercise, and was associated with significant reductions in cadence, heart rate and plasma glucose concentration (P < 0.05). These results demonstrate that when compared with time-trial cycling performed after a HC diet, reduced CHO availability does not initially alter self-selected work rate in endurance athletes who are deceived of their CHO status prior to exercise. This finding suggests that reduced work rate during exercise following lowered CHO intake may, in part, be a consequence of the subject’s awareness of dietary CHO restriction rather than solely a physiologically mediated action. Further research is required to distinguish the influence of circulating glucose and peripheral glycogen availability on pacing strategy during prolonged exercise.     

Maximal voluntary hyperpnoea increases blood lactate concentration during exercise

Ventilatory work during heavy endurance exercise has not been thought to influence systemic lactate concentration. We evaluated the effect of maximal isocapnic volitional hyperpnoea upon arterialised venous blood lactate concentration ([lac⁻]_B) during leg cycling exercise at maximum lactate steady state (MLSS). Seven healthy males performed a lactate minimum test to estimate MLSS, which was then resolved using separate 30 min constant power tests (MLSS=207±8 W, mean ± SEM). Thereafter, a 30 min control trial at MLSS was performed. In a further experimental trial, the control trial was mimicked except that from 20 to 28 min maximal isocapnic volitional hyperpnoea was superimposed on exercise. Over 20–28 min minute ventilation, oxygen uptake, and heart rate during the control and experimental trials were 87.3±2.4 and 168.3±7.0 l min⁻¹ (P<0.01), the latter being comparable to that achieved in the maximal phase of the lactate minimum test (171.9±6.8 l min⁻¹), 3.46±0.20 and 3.83 ± 0.20 l min⁻¹ (P<0.01), and 158.5±2.7 and 166.8±2.7 beats min⁻¹ (P<0.05), respectively. From 20 to 30 min of the experimental trial [lac⁻]_B increased from 3.7±0.2 to 4.7±0.3 mmol l⁻¹ (P<0.05). The partial pressure of carbon dioxide in arterialised venous blood increased approximately 3 mmHg during volitional hyperpnoea, which may have attenuated the [lac⁻]_B increase. These results show that, during heavy exercise, respiratory muscle work may affect [lac⁻]_B. We speculate that the changes observed were related to the altered lactate turnover in respiratory muscles, locomotor muscles, or both.     

Antiarrhythmic Activity of Phytoadaptogens in Short-Term Ischemia-Reperfusion of the Heart and Postinfarction Cardiosclerosis

A course of treatment (16 mg/kg orally during 5 days) by Aralia mandshurica or Rhodiola rosea extracts reduced the incidence of ischemic and reperfusion ventricular arrhythmias during 10-min ischemia and 10-min reperfusion. Extracts of Eleutherococcus senticosus, Leuzea carthamoides, and Panax ginseng did not change the incidence of ischemic and reperfusion arrhythmias. Chronic treatment by aralia, rhodiola, and eleutherococcus elevated the ventricular fibrillation threshold in rats with postinfarction cardiosclerosis. Ginseng and leuzea did not change this parameter in rats with postinfarction cardiosclerosis. Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 147, No. 3, pp. 303–306, March, 2009     

Effect of <Emphasis Type="Italic">n</Emphasis>-tyrosol on blood viscosity and platelet aggregation

Experiments on rats showed that n-tyrosol limited the increase in blood viscosity during thermal exposure at a shear rate of 5–300 sec⁻¹ and inhibited ADP-induced platelet aggregation. The effects of n-tyrosol are comparable to that of pentoxyphylline. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 143, No. 1, pp. 67–69, January, 2007     

Prooxidant-antioxidant state of the organism during oxidative stress and correction of the L-arginine-NO system

The prooxidant-antioxidant balance in rats with oxidative stress was studied during correction of the L-arginine-NO system. Oxidative stress was induced by intravenous injection of E. coli lipopolysaccharide. Under conditions of oxidative stress the prooxidant-antioxidant imbalance was least pronounced during selective correction of the L-arginine-NO system. L-Arginine and nonselective NO synthase inhibitor had little protective effect. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 141, No. 4, pp. 368–370, April, 2006     

Determinants of 2,000 m rowing ergometer performance in elite rowers

This study examined the physiological determinants of performance during rowing over 2,000 m on an ergometer in finalists from World Championship rowing or sculling competitions from all categories of competion rowing (19 male and 13 female heavyweight, 4 male and 5 female lightweight). Discontinuous incremental rowing to exhaustion established the blood lactate threshold, maximum oxygen consumption (V˙O_2max) and power at V˙O_2max; five maximal strokes assessed maximal force, maximal power and stroke length. These results were compared to maximal speed during a 2,000 m ergometer time trial. The strongest correlations were for power at V˙O_2max, maximal power and maximal force (r=0.95; P<0.001). Correlations were also observed for V˙O_2max (r=0.88, P<0.001) and oxygen consumption (V˙O₂) at the blood lactate threshold (r=0.87, P=0.001). The physiological variables were included in a stepwise regression analysis to predict performance speed (metres per second). The resultant model included power at V˙O_2max, V˙O₂ at the blood lactate threshold, power at the 4 mmol·l^–1 concentration of blood lactate and maximal power which together explained 98% of the variance in the rowing performance over 2,000 m on an ergometer. The model was validated in 18 elite rowers, producing limits of agreement from –0.006 to 0.098 m·s^–1 for speed of rowing over 2,000 m on the ergometer, equivalent to times of –1.5 to 6.9 s (–0.41% to 1.85%). Together, power at V˙O_2max, V˙O₂ at the blood lactate threshold, power at 4 mmol·l^–1 blood lactate concentration and maximal power could be used to predict rowing performance. Electronic Publication     

<Emphasis Type="Italic">Ex vivo</Emphasis> production of interferon-γ, tumor necrosis factor-α, and interleukin-6 by mouse macrophages during infection with <Emphasis Type="Italic">M. bovis</Emphasis> and <Emphasis Type="Italic">M. tuberculosis</Emphasis> H37Rv

Ex vivo production of IFN-γ, TNF-α, and IL-6 by mouse peritoneal macrophages was studied during successive infection with the vaccine strain M. bovis BCG and virulent strain M. tuberculosis H37Rv. The increase in the concentrations of TNF-α and IL-6 did not depend on the sequence of macrophage infection with the vaccine or virulent strain, but was related to the presence of the vaccine strain M. bovis BCG in the medium. IFN-γ production depended on infection of macrophages with the virulent strain M. tuberculosis H37Rv. The concentration of IFN-γ was maximum during primary infection with the virulent strain and did not increase after successive infection with the virulent and vaccine strain. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 144, No. 11, pp. 552–555, November, 2007