Blood Lactic Acid Concentration Research Articles

Improved Physical Performance after Treatment of Renal Anemia with Recombinant Human Erythropoietin

The physical performance of 12 anemic patients on renal dialysis was investigated following treatment of renal anemia with recombinant human erythropoietin (rhEPO; 40-120 U/kg, 3 times a week). Exercise intensity at a heart rate of 130 beats/min (PWC130) on a bicycle ergometer was assessed before rhEPO treatment, after reaching the target hematocrit (73 +/- 18 days), and in the maintenance phase (211 +/- 53 days). Hemoglobin concentrations measured at these time points were 7.3 +/- 1.2, 11.9 +/- 1.5, and 12.1 +/- 1.4 g/dl, respectively. PWC130 rose from 77 +/- 27 to 104 +/- 37 and 104 +/- 51 W, respectively. Aerobic threshold (i.e. blood lactic acid concentration of 2 mmol/l) shifted to higher workloads indicating improved muscle oxygen supply.

Glucoregulatory hormones in man at high altitude

Concentrations of glucose, lactic acid, free fatty acid (FFA), insulin, cortisol and growth hormone (GH) in the blood were monitored in 15 euglycaemic men (sojourners, SJ) at sea level (SL) and while at altitudes of 3500 m and 5080 m, in acclimatised low landers (ALL) and in high altitude natives (HAN). In SJ, blood glucose and insulin concentrations showed a significant increase on the 3rd and 7th day after arrival at high altitude (HA), thereafter returning to sea level values and remaining the same during the entire period of their stay at 3500 m. Subsequently, on arrival at higher altitude (5080 m) the glucose concentrations again showed an increase over the preceding values and returned to SL values on day 41 while at 5080 m. A significant increase in cortisol concentrations was seen on day 3 after arrival at HA and the increased levels were maintained until day 21 at 3500 m. The cortisol concentrations on day 30 after arrival at 5080 m came down to SL values and remained unchanged thereafter. No appreciable change in GH and FFA was seen during the sojourn at HA. On the other hand, blood lactic acid concentration decreased significantly. There was no difference between the fasting glucose concentrations in ALL at 3500 m and in HAN at 3500 m and 4200 m compared to values of SJ at SL, whereas ALL at 4200 m had higher glucose values. Concentrations of plasma insulin and GH in ALL and HAN were higher than the values of SJ at SL, whereas cortisol values did not show any difference. These observations indicated that at HA the glucose values were high for the insulin concentration observed and might have been due to increased secretion of GH by the pituitary gland.

VI. The Energetic Significance of Lactate Accumulation in Blood at Altitude

The O2 equivalent of lactic acid accumulation in blood was estimated from data on ten subjects acclimatized to altitudes up to 6500 m in the course of a Mt. Everest expedition. The calculated value of the O2 equivalent of La by standard least squares regression was 2.07 +/- 0.4 l O2 for a rise of blood lactic acid concentration [Lab] of 1 g per liter of blood (2.92 ml O2 per kg of body weight per 1 mM increase in blood lactate). This value, as well as the value obtained by the regression procedure suggested by Brace (2.84 +/- 0.5 l), was not significantly different from the previously reported value of 2.38 +/- 0.22 (14) for sea-level conditions. This finding indicated that, after La equilibrium is achieved, the redistribution of La among extra- and intracellular body compartments, as reflected by [Lab], appears not to be substantially affected by chronic hypoxia. The calculated maximum lactic O2 debt values at the Mt. Everest base camp (5350 m) were 1.26 and 1.42 liters for acclimatized Caucasians and for Sherpas, respectively. The amount of the measured maximum O2 debt at altitude was somewhat increased by pure O2 breathing (1.53 vs 1.26 l).

Cochlear hypoxia and the compound action potentials.

A relatively restricted area, including the ear, was perfused in guinea pigs with hypoxic blood having a pO2 of 10, 20, and 30 mm Hg, respectively. The changes induced to the cochlear action potentials were analyzed and the results compared with those obtained in a previous study in which the guinea pigs were rendered hypoxemic by ventilating them with air entrapped in a closed circuit from which the CO2 was continuously absorbed. The changes induced to the cochlear action potentials by both methods were very similar. However, while using the territorial model for inducing hypoxia, 75% of the animals showed a threshold shift at a blood pO2 of 20 mm Hg and with the general model all the animals showed a threshold shift at 25 mm Hg blood pO2. In other words, if the hypoxic condition affected the whole body, other factors such as a slight, but continuous tendency to acidosis with significant increase in blood lactic acid concentration could join the oxygen deficit in affecting cochlear function.

Hypothalamic, rectal, and muscle temperatures in exercising dogs: effect of cooling.

To investigate mechanisms that may be involved in the prolongation of exercise performance with body cooling hypothalamic (Thy), rectal (Tre), and exercising muscle (Tm) temperatures, as well as the heart rate, respiratory rate, blood lactic acid concentration ( [LA] ), and plasma osmolality (Osm) were measured in five dogs during exhaustive treadmill exercise at an ambient temperature (Ta) of 22 +/- 1 degree C without cooling (control) and with external cooling by use of ice packs. In both series of experiments, dehydration of animals was prevented. Compared with exercise with noncooling, exercise with cooling resulted in 1) increased exercise duration from 90 +/- 14 to 145 +/- 15 min (62%, P less than 0.05); 2) attenuated increases in Thy, Tre, and Tm; 3) decreased respiratory and heart rates; and 4) lowered LA. Significant negative correlations were found between both Tm and delta Tm attained at 60 min of the run and time of exercise until exhaustion (r = -0.72 and -0.74, respectively; P less than 0.02). This work failed to differentiate clearly changes or equilibrium levels of brain, core, or muscle temperature as separate factors affecting work tolerance. However, the inverse relationship between Tm reached at 60 min of the run (in both experiments) and the total duration of exercise indicates that sustained muscle hyperthermia may largely contribute to limitation of working ability.

Differences in twins: The importance of birth order

Despite the clinical impression that firstborn twins do better than second-born twins, recent reports have shown no difference in perinatal mortality between them. In order to evaluate differences in twins, more sensitive means than perinatal deaths are necessary. This study examines differences between 80 firstborn and second-born twin pairs with respect to Apgar score, umbilical venous and arterial blood gas, and acid-base data. The umbilical venous and arterial blood Po2, Pco2, base deficit, pH, and lactic acid concentration were measured in paired samples and compared with the paired t test and ξ2 when applicable. Statistically significant differences favoring twin A, the firstborn, were found in 1-minute Apgar score, umbilical venous pH, Po2, and Pco2, and umbilical arterial Po2. The other factors in umbilical venous and arterial blood did not show statistically significant differences. When these parameters were examined with respect to route of delivery, monochorionic and dichorionic twins, interval between twins, and vertex twins only, with the possible effects of malpresentation eliminated, the results persistently favored the firstborn twin. Thus it is unequivocally demonstrated that there are substantial differences at birth favoring the first twin, despite similar perinatal mortality for both. The data suggest that the second-born twin has potentially greater susceptibility to hypoxia and trauma.

Trends in continuous metabolic monitoring during experimental fetal distress.

Intermittent, progressive maternal aortic occlusions were used to produce fetal distress in the fetuses of six pregnant dogs at term. Fetal heart rate and fetal tissue surface pH were continuously recorded and were compared to fetal blood pH, pCO2, pO2 and lactic acid values determined from intermittent sampling. Baseline fetal heart rate was an insensitive indicator of fetal blood pH, tissue surface pH, or of fetal blood lactic acid concentrations. "Delayed" decelerations in fetal heart rate following an occlusive episode were uniformly produced after minimal stress and also did not correlate well with these variables. On the other hand, fetal blood lactic acid concentrations remained elevated even after occlusive episodes were discontinued and other variables had returned to baseline values.

Cardiac function and myocardial metabolism during tachycardia induced by atrial and ventricular pacing.

We studied atrial and ventricular pacing-elicited tachycardia in mongrel adult dogs to evaluate ensuing changes in cardiac function and myocardial metabolism. The aortic pressure, left ventricular pressure, and left ventricular end diastolic pressure were measured under anesthesia. Using an electromagnetic flow-meter, coronary blood flow and aortic blood flow were recorded simultaneously with the recording of ECG. Atrial and ventricular pacing (1.5 times the basic heart beat) were performed using a catheter introduced via the jugular vein and positioned in the coronary venous sinus. Aortic blood and coronary venous blood were sampled for determination of blood oxygen concentrations and lactic acid concentrations. The results showed that oxygen extraction changed little compared with the control study on atrial pacing (AP) and ventricular pacing (VP) whereas the lactate uptake showed little change in the AP control study but decreased slightly in the VP study. It appears that aerobic metabolism occurs during both AP and VP when the pacing rate is not more than 1.5 times the basic heart beat.

Errors in predicting functional capacity for postmyocardial infarction patients using a modified Bruce protocol

Clinically, the modified Bruce protocol is widely used to predict functional capacity in postmyocardial infarction (post-MI) patients. However, it has been suggested that post-MI patients have lower oxygen uptakes for standard workloads. In order to study this, we measured oxygen uptake (V̇O 2) and venous blood lactic acid concentration in 12 post-MI patients and 12 normal male subjects during a modified Bruce treadmill protocol. During the first four stages of the protocol, mean oxygen uptake was significantly lower (1.0 to 6.2 cc · kg −1 · min −1; p < 0.001) for the post-MI patients than for the normal male subjects. Venous blood lactic acid concentrations were different only at stage 4. However, a higher respiratory exchange ratio was observed for post-MI patients ( p < 0.001 at stage 3), suggesting an increased anaerobic metabolism and adequate buffering of lactic acid. The post-MI patient's measured V̇O 2 for three stages of the protocol ranged from 1.8 to 7.3 cc·kg −1 · min −1 lower than the Bruce prediction for cardiac patients. In addition, maximal measured VO 2 for the post-MI patients ranged from 3.7 to 11.2 cc·kg −1 · min −1 lower than predicted V̇O 2 derived from the normal subjects. These data suggest myocardial damage may slow oxygen uptake kinetics, thus increasing the oxygen deficit at standard workloads during progressive exercise. An increased respiratory exchange ratio secondary to the buffering of lactic acid suggests that anaerobic metabolism may compensate for this oxygen deficit.

Cardiorespiratory responses to intestinal injection of carbon monoxide.

Experiments were conducted to investigate whether direct, intestinal injection of carbon monoxide (CO) can be used as a reliable method of exposing rats to CO. Laboratory rats were anesthetized with urethane. A laparotomy was performed and the small intestine isolated. The pylorus and ileocaecal valve were ligated and air or 100% CO (75 ml/kg) was injected directly into the small intestine. Heart rate and respiratory rate were monitored by impedance pneumography. COHb and blood lactate concentrations were determined spectrophotometrically. CO was rapidly absorbed from the intestinal tract and COHb levels reached 70.9 +/- 1.3% one hr after treatment. After 45 min, heart rate decreased in the CO-injected animals to 86% of pre-injection value. Blood pressure decreased rapidly to levels significantly lower than controls 5 min after treatment. Respiratory rate decreased to levels significantly lower than controls 55 min after treatment. CO treatment resulted in a 4-fold increase in blood lactate concentration. The results indicate that 100% CO injected directly into the small intestine is absorbed rapidly and the resulting elevated COHb levels cause a rapid decrease in blood pressure, a decrease in heart and respiratory rates, and an increase in the blood's lactic acid concentration.

Cardiovascular and metabolic responses of trained and untrained middle-aged men to a graded treadmill walking test.

A treadmill walking test was developed in order to provide a suitable method of assessing the fitness levels of sedentary middle-aged men (mean age, 44.3 yrs) at submaximal intensity. The incremental stages of the test enabled subjects to terminate the workload whenever undue discomfort was experienced. The test procedure was used in a preliminary experiment to compare the cardiovascular and metabolic responses of trained and untrained middle-aged men to exercise. Heart rate responses to the test were significantly higher (p less than 0.01) in the untrained, compared with the trained, men as were the post-exercise blood lactic acid concentrations (p less than 0.01), Respiratory Exchange Ratios (p less than 0.01), Ventilatory Equivalents (p less than 0.05) and Rate of Perceived Exertion (p less than 0.01). However, there were no differences in the oxygen cost of walking between the two groups.

Is Lactic Acid Related to Delayed-Onset Muscle Soreness?

In brief: The authors tested the hypothesis that delayed-onset muscular soreness after running is related to the production of lactic acid during the exercise. Blood lactic acid concentration was measured before and during 45 minutes of treadmill running, one time on the level and once at a-10% incline. Blood lactic acid concentration and subjective sensations of muscular soreness were assessed at intervals for 72 hours after the runs. Lactic acid concentration was significantly increased during running on the level, but subjects experienced no significant postexercise muscular soreness. Lactic acid was never elevated in downhill runners, but subjects experienced significant delayed-onset soreness. Results indicated that lactic acid is not related to exercise-induced delayed-onset muscle soreness.

Aerobic diving limits of immature Weddell seals

1. Consistent with previous studies on adult seals, post-dive blood lactic acid (LA) concentrations in immature Weddell seals did not increase above resting levels after short voluntary dives (Fig. 1). 2. Following longer dives, peak blood LA values increased rapidly according to the duration of the dive (Fig. 1). 3. The peak post-dive blood LA concentration relative to dive duration demonstrate that there is a positive relationship between aerobic dive limit (ADL) and body size (Fig. 1 and 3). 4. The ADL for 130 to 145 kg seals was about 10 min, and it was 13 min for 185 to 205 kg seals (Fig. 1). 5. The calculation of the ADL from available oxygen stores correlates well with the lactate/endurance curve intercept, where peak post-dive LA concentration rises rapidly above resting levels as the dive duration increases in adult and immature animals (Table 2 and Fig. 3). 6. Of total dives, 4% of the dive durations exceeded the measured ADL in 130 to 145 kg seals and 8% in the 205 kg seal (Fig. 2). 7. Dive depths of immature seals did not exceed 315 m (Table 1).

Changes in fetal and maternal blood at the end of pregnancy and during parturition in the pig

Fetal and maternal blood gas tensions, pH, packed cell volume and glucose, fructose and lactic acid concentrations were monitored during the last two days of gestation, during parturition and and the first hour after birth. Blood samples were taken by means of indwelling catheters (implanted seven to 14 days before parturition) from 12 fetuses in seven sows. All fetuses were liveborn at a mean gestational age of 113.1 days. The significant finding was that all variables in fetal blood were stable during labour and, although mild hypercapnia was present during the last three hours, no significant changes in mean values were seen until those of samples taken within 15 minutes of birth. In some fetuses, no changes were seen until after birth, while in others pH and pO2 values declined during the last hour of fetal life. Immediately after birth a rapid increase in pO2 and decrease in pCO2 followed the onset of respiration. Blood pH fell during the first 30 minutes after birth and this fall was accompanied by increasing blood lactic acid concentrations. Blood glucose concentrations rose rapidly in the first 15 minutes after birth and were maintained during the first hour despite separation of the piglets from the sow. There was a transient, but significant, increase in packed cell volume during the period from 15 minutes before to 15 minutes after birth. Maternal values for all variables measured remained virtually unchanged during delivery.

Criteria for pulmonary and respiratory failure in COPD patients - a theoretical study based on clinical data.

In 58 patients with chronic obstructive pulmonary disease, pulmonary gas exchange efficiency was assessed by the ratio: arterial to mixed venous PO2 difference (efficient part) versus alveolar to mixed venous PO2 difference (driving pressure for O2 transport). Patients with PaO2 below 75 mm Hg had a ratio lower than 50%. Patients with PaO2 below 60 mm Hg had lower values for arterial to mixed venous O2 content difference and higher blood lactic acid concentration than patients with PaO2 over 60 mm Hg. Arterial to mixed venous PO2 difference decreased linearly against PaO2 till PaO2 reached 60 mm Hg from which the difference began to attenuate. These figures in PaO2 are in close agreement with the criteria for pulmonary failure presented by the Ciba guest symposium (PaO2 below 75 mm Hg) and for respiratory failure by the National Heart, Lung and Blood Institute (PaO2 below 60 mm Hg).

Changes in the nucleotide triphosphate/haemoglobin and nucleotide triphosphate/red cell ratios of rainbow trout, Salmo gairdneri Richardson, subjected to prolonged starvation and bleeding

The nucleotide triphosphate/haemoglobin (NTP/Hb) and nucleotide triphosphate/red cell (NTP/cell) ratios of rainbow trout increased during prolonged starvation. A decline was noted in blood lactic acid concentration. Red cell count, haemoglobin concentration and haematocrit also declined. Changes in mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) were found not to be significant. The NTP/Hb and NTP/cell ratios of both fed and starved trout rose seven days following a 15% reduction in blood volume by cardiac puncture. A rise in whole blood NTP concentration was found only in the bleeding response of fed animals. No significant change was noted in blood lactic acid concentration. The decline in haematocrit was significant only in the starved group. In both groups, however, red cell count and blood haemoglobin concentration fell. MCV rose whereas MCHC declined in all bled animals. Changes in MCH were not significant in either group. Negative correlations were noted between red cell count and both the NTP/Hb and NTP/cell ratios and between haemoglobin concentration and the NTP/Hb ratio. Positive correlations were seen between the two ratios and between red cell count and haemoglobin concentration.

Effect and fate of orally administered lactic acid in rats.

We investigated the effect and the fate of an extremely high amount of orally administered lactic acid in rats. The dosed amount of lactic acid, 390 mg per 200 g body weight (30 times higher than that normally detected in the stomach of rats), was determined from the results of observation of acute toxicity of lactic acid in rats. Six hours after the administration of excess lactic acid together with 10 muCi of L-[U-14C]Lactic acid and 10 muCi of D-[U-14C]lactic acid, rats were sacrificed and the pH of the blood, the amount of lactic acid in each organ, L-lactate dehydrogenase (LDH) and some other enzyme activities and incorporation of radioactivities in each fraction of certain organs were measured. The control rats were given the labeled lactic acid and the same volume of water in place of cold lactic acid. Significant decrease of blood pH (delta- pH = 0.14) and increase of blood lactic acid concentration (2-fold) were observed. However, these differences were no longer observed at 24hr after the administration. The amount of lactic acid degraded to expired CO2 was 42.4% in the experimental group, whereas it was 61.3% in the control group. Radioactivities incorporated into protein and lipid fractions in the experimental group were higher than those in the control group, 3.8 and 4.9 times, respectively. It was suggested that an extremely high amount of orally administered lactic acid was utilized as an energy source, and that an excess of lactic acid was incorporated into protein and lipid in addition to degradation into CO2.

Endotoxin toxicity in rats with 6-sulfanilamidoindazole arthritis

Seven oral administrations of 6-sulfanilamidoindazole (6-SAI) to 10- to 12-month-old rats sensitized the animals to endotoxin, with dosages as small as 2.5 microgram causing death in 80% of animals. Endotoxin in a dosage of 3,000 microgram was not lethal for nonmedicated control animals. 6-SAI-treated 1-month-old rats were not as sensitive to endotoxin as aged animals. The sulfonamide-induced sensitivity to endotoxin could not be passively transferred and could not be explained by blockade of the reticuloendothelial system or impairment of endotoxin detoxification. 6-SAI administration was associated with both depletion of liver glycogen and lowering of blood glucose concentration without changes in blood lactic acid concentration. Disseminated intravascular coagulation is believed to be involved in the pathogenesis of shock and death as evidenced by: (i) concomitant decreases in plasma fibrinogen concentration and elevations in fibrin degradation products after endotoxin challenge; (ii) protection against lethal actions of endotoxin by pretreatment with heparin. Treatment of 6-SAI-medicated rats with glucocorticoids before endotoxin challenge protected the animals against lethal doses of endotoxin and prevented deposition of fibrin thrombi in the glomerular capillaries.

Die Wirkung des Futterentzuges auf einige Parameter des Pansensaftes und Blutes bei Schafen

In order to find out how short-time denutrition changes the concentration of some substances in the rumen fluid and the blood, tests with full-grown sheep were carried out. Fodder was withheld from sheep with inserted Jarrett fistulae for 48 hours after normal feeding. After 48 hours the animals were given concentrated fodder, after 52 hours exclusively hay. From the 72nd hour onwards the animals were provided with fodder as usual. Samples of the rumen fluid and blood samples were taken at the beginning of the test, after the last normal feeding and then in the 24th, 32nd, 48th, 52nd, 56th, 72nd and 96th hour. We could find out that, during the 48-hour denutrition, the pH-value of the rumen fluid turned alkaline and the concentrations of ammonia, volatile fatty acids and lactic acid decreased. The protein metabolism underwent a rapid change in the organism. The protein content of the blood plasma decreased, above all the albumin content, as well as the concentration of glycoproteins and volatile amino acids. Among the various amino acids, the concentration of glycine increased highly, that of alanine and valine just slightly. The concentration of most amino acids decreased or--of some of them remained the same. Among the paramters that are characteristic of lipid and carbohydrate metabolism, the total content of lipids and cholesterin decreased, and so did the concentration of blood sugar, lactic acid and pyruvic acid in the blood plasma. The results indicate that short-time denutrition has a considerable influence on the rumen fermentation and the intermediary metabolism of ruminants. The quickly arising lack of energy of ruminants slows down the protein synthesis and increases the glyconeogenesis from amino acids. The tissue is supplied with energy by the mobilisation of lipids.

Metabolic effects of heavy physical training on female 'age-group' swimmers.

Twelve female age-group swimmers and twelve female controls, aged ten to sixteen, performed a pre-training discontinuous maximal cycle ergometer test to determine the capacities of their anaerobic (alactacid and lactacid) and aerobic energy systems. Heart rate and oxygen uptake were determined during rest, exercise, and recovery. Blood samples were collected before and after exercise for determination of blood lactic acid concentrations. Tests were readministered to both groups immediately following the swimmers' competitive season. It was concluded that female swimmers possess significantly superior oxygen transport systems as compared to the untrained controls and that the high level of aerobic fitness is maintained throughout their training programme.