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At least 199 records · Page 11Linked to original sources
PubMed1998

Variation in CD4+ T and CD8+ T lymphocyte subpopulations in bovine mammary gland secretions during lactating and non-lactating periods.

Mammary gland secretions (MGS) of dairy cows at different stages of lactation were studied by immunofluorescence cytometry for T lymphocyte subpopulations using monoclonal antibodies. During early and late lactation, the mean ratio of CD4+/CD8+ T lymphocytes in the MGS was 0.5 and 0.8, respectively. A large proportion of the CD8+ cells coexpressed the activation molecule, ACT2. These results indicate that CD8+ ACT2+ cells constituted the major phenotype in the T lymphocytes throughout lactation. In the mammary gland of cows in which drying off was induced, however, the proportion of CD8+ ACT2+ cells decreased, resulting in the increase of the CD4+/ CD8+ ratio in the MGS. At the late non-lactation stage, the ratio reached a maximal level of 2.5-4.0, which was similar to or higher than that found in the peripheral blood. This selective increase of CD4+/CD8+ cell ratio correlated with an increase in the concentrations of total cells in the MGS. This high CD4+/CD8+ cell ratio during the drying off stage rapidly decreased just before parturition, correlating with the decrease in concentrations of total cells in the MGS, reaching the lowest level at early lactation. The cells isolated at the non-lactation stage produced the cytokines IL-2 and IL-4 at a level much higher than those of cells isolated at lactation stages, and the increases were correlated with the CD4+ T lymphocyte proportions.

Animals↗
PubMed1986

Hepatic lactate uptake is enhanced by low pH at low lactate concentrations in perfused rat liver.

The effect of pH on lactate uptake was studied in perfused liver of rats starved for 48 h. At both low pH (6.8) and normal pH (7.4) lactate uptake was a linear function of lactate concentration in input medium in the range 0.4-1.5 mmol/l. In the lower concentration range (0.4-0.8 mmol/l) the rate of lactate uptake was 30% higher at pH 6.8 than at pH 7.4. At pH 6.8 lactate uptake was independent of whether PCO2 was 2.7 or 5.3 kPa. We suggest the increased rate of lactate uptake at low pH and concentrations lower than 0.8 mmol/l was due to the stimulatory effect of H+ on the lactate carrier.

Acidosis↗
PubMedDate not supplied

Influence of feed intake during pregnancy and lactation on fat body reserve mobilisation, plasma leptin and reproductive function of primiparous lactating sows.

From day 23 of pregnancy, 24 gilts received either a medium (M, n = 16) or a high (H, n = 8) level of feeding calculated to meet 115% or 190% of energy for maintenance, respectively. During lactation, all H sows were fed ad libitum (H-AL) whereas M sows were fed either ad libitum (M-AL, n = 8) or were restricted (M-RE, n = 8) to the amount of feed ingested by H-AL sows. Increased feed intake during pregnancy increased live weight, backfat thickness, and estimated body lipid and protein on days 4 and 25 of lactation (P < 0.05). It also resulted in lower feed intake and higher lipid mobilisation during lactation (P < 0.05) without a detrimental influence on milk production. Activities of malic enzyme and glucose-6-phosphate dehydrogenase from neck fat samples were higher in H than M sows on day 4 (P < 0.05). They decreased during lactation in H sows (P < 0.05). Mean diameter of adipocytes decreased during lactation in the 3 groups (P < 0.05) but did not differ between groups on days 4 and 25. Plasma leptin on days 4, 11, 18 and 25 was higher in H than in M sows (P < 0.05) but was not influenced by lactational feed intake. Neither measured characteristics of gonadotrophin secretion on day 22, nor of ovarian activity on day 26, were significantly influenced by the level of feeding during pregnancy or lactation.

Adipose Tissue↗
PubMed1990

Lactate balance in perfused rat liver: effects of glucose concentration, flow and low pH on glucose to lactate flux.

The effects of medium glucose concentration (0-20 mmol l-1), pH (7.4 and 6.8) and flow (100 to 33% normal) on lactate uptake and glycolytic flux from 6-3H glucose were studied in perfused livers from 48-h starved rats. At both pH values, the glycolytic flux increased proportionally with the medium glucose concentration. Maximum glycolytic flux at 20 mmol l-1 glucose in the medium was 0.5 mumol min-1 g-1 liver (C6-units) at pH 7.4. At pH 7.4 and 20 mmol l-1 glucose the glycolytic flux decreased approximately proportional with flow. At pH 6.8 the glycolytic flux was extremely low and independent of flow. At flow 33% normal and pH 7.4 a net lactate production was accounted for by glycolysis from medium glucose concentration, indicating virtually no simultaneous lactate uptake. In contrast, at pH 6.8 net lactate production accounted for only half the glycolytic rate, indicating that lactate uptake occurred simultaneously with glycolysis. Thus, glucose-to-lactate flux in liver (as in muscle and brain) is subject to inhibition by low pH, and lactate uptake is enhanced by low pH.

Animals↗
PubMed2001

Increased rat mammary tissue vitamin A associated with increased vitamin A intake during lactation is maintained after lactation.

Although increases in dietary vitamin A increase milk vitamin A, little is known about effects of vitamin A intake on mammary tissue vitamin A levels during and after the reproductive cycle. First, we measured vitamin A concentrations in milk, mammary tissue and liver of lactating rats fed 0, 4, or 50 micromol of vitamin A/kg diet during pregnancy and through d 12 of lactation. Liver vitamin A concentration was significantly affected by diet in lactating females and pups 12 d after parturition. Milk vitamin A concentrations were significantly higher (7.1 +/- 2.2 micromol/L, n = 8) in dams fed 50 micromol/kg than in those fed 0 or 4 micromol/kg (1.9 +/- 0.3, n = 5 and 2.9 +/- 0.7 micromol/L, n = 7; P < 0.001), as were mammary tissue vitamin A concentrations (5.1 +/- 1.1 versus 2.2 +/- 0.4 and 2.4 +/- 0.6 nmol/g; P < 0.001). Next, we maintained female rats on 50 or 10 micromol vitamin A/kg diet during pregnancy and lactation and then on 4 micromol/kg diet after pups were weaned on d 21. On d 21, mammary tissue vitamin A concentrations were 3.14 +/- 0.75 versus 1.52 +/- 0.21 nmol/g in dams fed 50 versus 10 micromol/kg (n = 4/group; P < 0.001). Mammary tissue vitamin A concentrations were not significantly affected by time from 7 to 49 d after lactation and averaged 8.5 +/- 0.4 and 4.9 +/- 0.8 nmol/g on d 49 in dams fed 50 versus 10 micromol/kg (n = 4; P < 0.001). We conclude that diet-induced differences in rat mammary tissue vitamin A developed during pregnancy and lactation are maintained for > or =7 wk after lactation.

Animals↗
PubMed2002

Method of lactate elevation does not affect the determination of the lactate minimum.

PURPOSE: The aim of the study was to examine the effects of different lactate elevation protocols on the determination of the lactate minimum (Lac(min)) point. METHODS: Eight highly trained racing cyclists each completed four continuous ramp lactate minimum tests using the following blood lactate elevation protocols: 1) continuous ramp maximal aerobic power (RMP(max)) assessment, 2) 30-s maximal sprint, 3) 40-s maximal sprint, and 4) two 20-s maximal sprints separated by a 1-min recovery. Each blood lactate elevation protocol was followed by a 5-min active recovery leading into a continuous ramp test commencing at a power of 60% of RMP(max), using a 6 W x min ramp rate, lasting 15 min. RESULTS: Peak [La](b) values were significantly higher (P > 0.05) after the RMP(max) compared with all other protocols and higher in the 40-s versus 30-s sprint. However, by the start of Lac(min) ramp, [La](b) after the RMP(max) was no longer higher than the 40-s sprint, but Lac(min) [La](b) was similar for all protocols. This resulted in no differences in the total decline of [La](b) measured as a percentage from the highest to the lowest value. At Lac(min) point, there were no significant differences in power (P > 0.05), but heart rate was higher in the RMP versus 2 x 20 s and VO(2) was significantly higher after the 40 s compared with the 2 x 20 s protocol. CONCLUSION: This study demonstrated that the determination of lactate minimum power in cycling is not dependent upon the lactate elevation protocol.

Adult↗
PubMed2004

Hydrogen peroxide production in Streptococcus pyogenes: involvement of lactate oxidase and coupling with aerobic utilization of lactate.

Streptococcus pyogenes strains can be divided into two classes, one capable and the other incapable of producing H2O2 (M. Saito, S. Ohga, M. Endoh, H. Nakayama, Y. Mizunoe, T. Hara, and S. Yoshida, Microbiology 147:2469-2477, 2001). In the present study, this dichotomy was shown to parallel the presence or absence of H2O2-producing lactate oxidase activity in permeabilized cells. Both lactate oxidase activity and H2O2 production under aerobic conditions were detectable only after glucose in the medium was exhausted. Thus, the glucose-repressible lactate oxidase is likely responsible for H2O2 production in S. pyogenes. Of the other two potential H2O2-producing enzymes of this bacterium, NADH and alpha-glycerophosphate oxidase, only the former exhibited low but significant activity in either class of strains. This activity was independent of the growth phase, suggesting that the protein may serve in vivo as a subunit of the H2O2-scavenging enzyme NAD(P)H-linked alkylhydroperoxide reductase. The activity of lactate oxidase was associated with the membrane while that of NADH oxidase was in the soluble fraction, findings consistent with their respective physiological roles, i.e., the production and scavenging of H2O2. Analyses of fermentation end products revealed that the concentration of lactate initially increased with time and decreased on glucose exhaustion, while that of acetate increased during the culture. These results suggest that the lactate oxidase activity of H2O2-producing cells oxidizes lactate to pyruvate, which is in turn converted to acetate. This latter process proceeds presumably via acetyl coenzyme A and acetyl phosphate with formation of extra ATP.

Aerobiosis↗
PubMed1998

Glucose and lactate metabolism in C6 glioma cells: evidence for the preferential utilization of lactate for cell oxidative metabolism.

13C and 1H nuclear magnetic resonance spectroscopy (NMR) was used to investigate the metabolism of L-lactate and D-glucose in C6 glioma cells. The 13C enrichment of cell metabolites was examined after a 4-h incubation in media containing 5.5 mM glucose and 11 mM lactate, each metabolite being alternatively labelled with either [1-13C]D-glucose or [3-13C]L-lactate. The results indicated that exogenous lactate was the major substrate for oxidative metabolism. They were consistent with the concept of the existence of 2 pools of both lactate and pyruvate, of which 1 pool was closely connected with exogenous lactate and oxidative metabolism, and the other pool was closely related to glycolysis and disconnected from oxidative metabolism. The molecular basis of this behaviour could be related to different locations for the lactate dehydrogenase isoenzymes, as suggested by their immunohistochemical labelling.

Animals↗
PubMed1999

Overexpression of monocarboxylate transporter and lactate dehydrogenase alters insulin secretory responses to pyruvate and lactate in beta cells.

Previous investigations revealed low activities of lactate dehydrogenase (LDH) and plasma membrane monocarboxylate transporters (MCT) in the pancreatic beta cell. In this study the significance of these characteristics was explored by overexpressing type A LDH (LDH-A) and/or type 1 MCT (MCT-1) in the clonal INS-1 beta cells and isolated rat islets. Inducible overexpression of LDH-A resulted in an 87-fold increase in LDH activity in INS-1 cells. Adenovirus-mediated overexpression of MCT-1 increased lactate transport activity 3.7-fold in INS-1 cells. Although overexpression of LDH-A, and/or MCT-1 did not affect glucose-stimulated insulin secretion, LDH-A overexpression resulted in stimulation of insulin secretion even at a low lactate concentration with a concomitant increase in its oxidation in INS-1 cells regardless of MCT-1 co-overexpression. Adenovirus-mediated overexpression of MCT-1 caused an increase in pyruvate oxidation and conferred pyruvate-stimulated insulin release to isolated rat islets. Although lactate did not stimulate insulin secretion from control or MCT-1-overexpressing islets, co-overexpression of LDH-A and MCT-1 evoked lactate-stimulated insulin secretion with a concomitant increase in lactate oxidation in rat islets. These results suggest that low expression of MCT and LDH is requisite to the specificity of glucose in insulin secretion, protecting the organism from undesired hypoglycemic actions of pyruvate and lactate during exercise and other catabolic states.

Adenoviridae↗
PubMed2005

Impact of early lactation somatic cell count in heifers on milk yield over the first lactation.

The objective of this study was to estimate the impact of somatic cell count (SCC) in early lactation (SCCel) [measured between 5 to 14 d in milk (DIM)] of dairy heifers on test-day milk yield (MY) during the first lactation. In total, 117,496 four-weekly test-day records of 14,243 heifers were used. A multilevel regression analysis, which included test-day SCC among the explanatory variables, revealed that an increase by one unit of the natural log-transformed SCCel (LnSCCel) was on average associated with a decrease in MY of 0.13 kg/d later in lactation. As an example, a heifer with an SCCel of 50,000 cells/mL measured at 10 DIM was estimated to produce 119 and 155 kg more milk during its first lactation than heifers with a SCCel of 500,000 and 1,000,000 cells/mL, respectively. When not accounting for test-day SCC, the effect of LnSCCel on MY was larger, indicating that part of the negative impact of elevated SCCel was associated with elevated test-day SCC later in lactation.Furthermore, an elevated SCCel at 14 DIM had a larger impact than an equally elevated SCCel measured at an earlier DIM. In addition, the negative effect of an elevated SCCel remained present during almost the entire first lactation in a subgroup of heifers with a second test-day SCC </=50,000 cells/mL, suggesting that prevention rather than cure of an elevated SCCel should be preferred. This study stresses the importance of heifers having low SCCel, as an elevated SCCel will negatively affect milk production during the first lactation, probably via impairment of mammary function and, to a smaller extent, via elevated test-day SCC later in lactation.

Animals↗
PubMed1976

Hormone induced lactation in the cow. IV. Relationships between lactational performance and hormone concentrations in blood plasma.

Concentrations of progesterone, estrogen, and prolactin in plasma were compared among lactations induced in 29 cows by daily subcutaneous injections of .25 mg progesterone and .1 mg estradiol-17beta per kg body weight for 7 days. Superior, median, and inferior lactations were identified by ranking both weightage adjusted maximum milk yields in 7 consecutive days (average 144 +/- 9 kg) and days for milk yield to increase from 5 to 10 kg/day (15 +/- 3 days). Superior and inferior of the former averaged 189 and 101 kg, and their latter averaged 2 and 42 days. Plasma hormones were measured on day 0 before first treatment (day 1), and on days 7, 14, 17, 21, 24, 28, and 35. Superior lactations were associated with below-average progesterone and estrogen in plasma on day 0, rapid decreases in progesterone after day 7 and in estrogen after day 14, and increased prolactin after 7. In comparison, median lactations were associated with elevated progesterone and estrogen after day 17, but prolactin was similar to that of superior lactations. Inferior lactations were associated with decreased prolactin in plasma from days 21 to 35. We hypothesized that (a) first treatment should start 3 to 8 days after estrus, (b) daily doses of estradiol-17beta should be decreased with progesterone unchanged for the 7 days, and (c) estradiol-17beta alone should be continued for 7 days to improve hormonally induced lactations.

Animals↗
PubMed1985

Varying protein content and nitrogen solubility for pluriparous, lactating Holstein cows: lactation performance and profitability.

Effects on total lactation performance of varying ration crude protein (15.3 vs. 13.6% of dry matter) and nitrogen solubility (35 vs. 45% of total nitrogen) in early lactation was studied using 57 pluriparous Holstein cows. Grain was fed according to production so as to minimize change in body weight throughout lactation. Forages high in nitrogen solubility, corn and grass silages, were fed free-choice. Percent concentrate in ration dry matter was highest (64%) 5 to 8 wk postpartum and lowest (3%) 33 to 44 wk postpartum. Protein and nitrogen solubility were varied by formulating four protein supplements fed as 10% of the grain allocation, so differences in treatments applied narrowed as lactation progressed. Cows fed the medium-protein diets produced 196 kg more milk than those receiving low-protein diets, but their peak daily milk yield was only .6 kg higher. Cows receiving rations with reduced nitrogen solubility produced 347 kg more milk than those fed the higher solubility diets, but their peak daily milk yield was 1.0 kg lower. Income above fed cost for the lactation was highest and postpartum loss in body weight was least for cows receiving medium-protein and low-solubility rations in early lactation, but no differences were significant. Both milk yield (38.3 to 40.6 kg) and total dry matter intake (3.74 to 3.91% body weight) means were maximum 6 to 7 wk postpartum, but lactation performance was not proportional to peak milk yield. When cows are fed to minimize body fat mobilization, response to increased protein in the diet is small. Reducing nitrogen solubility of silage-based diets increased milk produced per unit grain fed. There were no adverse effects of treatments on breeding efficiency or herd health.

Animals↗
PubMed1995

Breast abscesses in Nigeria: lactational versus non-lactational.

This review of 299 cases of breast abscesses seen over a 10-year period (1981-1990) at the University of Calabar Teaching Hospital in Nigeria seeks to establish the current status of breast abscesses in the tropics. Lactational breast abscess constitutes 95% of breast abscesses while non-lactational breast abscess constitutes only 5% in this review. The commonest pathogen cultured from lactational breast abscess is Staphylococcus aureus and the disease responds to incision and drainage and systemic antibiotics, while non-lactational breast abscess is caused mostly by anaerobic organisms, usually with underlying mammary duct ectasia. The low incidence of non-lactational breast abscess corresponds to the low incidence of cigarette smoking and mammary duct ectasia in Nigerian women. While the high incidence of lactational breast abscess corresponds to the high rate of breast feeding and low level of personal hygiene in the low income group Nigerian women in which the disease is commonest. Economic recession has also reduced patronage of artificial feeds thus intensifying breast feeding and consequent lactational breast abscess.

Abscess↗
PubMed1996

The relationship between respiratory exchange ratio, plasma lactate and muscle lactate concentrations in exercising horses using a valved gas collection system.

A valved gas collection system for horses was validated, then used to examine the relationship between the respiratory exchange ratio (RER), and plasma and muscle lactate in exercising horses. Four healthy Standardbred horses were trained to breathe through the apparatus while exercising on a treadmill. Comparisons of arterial blood gas tensions were made at 3 work levels for each horse, without (control), and with the gas collection system present. At the highest work level, the arterial oxygen tension (PaO2) was significantly lower (P < 0.05), and the arterial carbon dioxide tension (PaCO2) was significantly higher (P < 0.05), than control levels when the apparatus was present; however arterial oxygen content remained unchanged. The horses completed a standardized incremental treadmill test on 4 occasions to determine the repeatability of measurements of oxygen consumption (VO2), carbon dioxide production (VCO2), inspired minute ventilation (VI), respiratory exchange ratio (RER), ventilatory equivalent for oxygen (VI/VO2), tidal volume (VT), and ventilatory frequency (VF). All gas exchange and respiratory measurements showed good reproducibility with the mean coefficient of variation of the 4 horses ranging from 3.8 to 12%. We examined the relationship between 3 indices of energy metabolism in horses performing treadmill exercise: respiratory exchange ratio (RER), central venous plasma and muscle lactate concentrations. A relationship between RER and plasma lactate concentration was established. To compare muscle and plasma lactate concentrations, the horses completed a discontinuous exercise test without the gas collection apparatus present. Significant relationships (P < 0.05), between plasma lactate concentration and RER, and between plasma and muscle lactate concentration, were described for each horse. The valved gas collection system produced a measurable but tolerable degree of interference to respiration, and provided reproducible measurements of gas exchange and ventilatory measurements. It was concluded that measurements of both gas exchange and blood lactate may be used to indicate increased glycolytic activity within exercising skeletal muscle.

Animals↗
PubMed2002

Transport of L-Lactate, D-Lactate, and glycolate by the LldP and GlcA membrane carriers of Escherichia coli.

To examine the substrate specificity of the membrane transport carriers LldP (L-lactate permease) and GlcA (glycolate permease) of Escherichia coli, a mutant strain lacking their structural genes and blocked in the metabolism of the tested substrates was constructed and transformed with a plasmid bearing either the lldP or the glcA gene. Each transformant acquired the ability to accumulate L-lactate, D-lactate, and glycolate against a high concentration gradient. Substrate accumulation was inhibited by carbonyl cyanide m-chlorophenylhydrazone, a hydrophobic proton conductor that dissipates proton motive force. Competition of (14)C-L-lactate transport by nonradioactive L-lactate, D-lactate, and glycolate in LldP synthesizing cells and competition of (14)C-glycolate transport by the same three substrates in GlcA synthesizing cells showed that both carriers effectively transported all three substrates with a K(i) value ranging from 10 to 20 microM. D-Lactate does not appear to have a permease of its own. Utilization of the compound depends mainly on LldP.

Acetic Acid↗
PubMed2001

The relationship between critical velocity, maximal lactate steady-state velocity and lactate turnpoint velocity in runners.

In cycle exercise, it has been suggested that critical power, maximal lactate steady state, and lactate turnpoint all demarcate the transition between the heavy exercise domain (in which blood lactate is elevated above resting values but remains stable over time) and the very heavy exercise domain (in which blood lactate increases continuously throughout constant-intensity exercise). The purpose of the present study was to assess the level of agreement between critical velocity (CV), maximal lactate steady-state velocity (MLSSV), and lactate turnpoint velocity (LTPV) during treadmill running. Eight male subjects [mean (SD) age 28 (5) years, body mass 71.2 (8.0) kg, maximum oxygen uptake 54.9 (3.2) ml.kg(-1).min(-1)) performed an incremental treadmill test for the determination of LTPV (defined as a sudden and sustained increase in blood lactate concentration ([La]) at approximately equals 2.0-5.0 mM). The subjects returned to the laboratory on eight or nine occasions for the determination of CV and MLSSV. The CV was determined from four treadmill runs at velocities that were chosen to result in exhaustion within 2-12 min. The MLSSV was determined from four or five treadmill runs of up to 30 min duration and defined as the highest velocity at which blood [La] increased by no more than 1.0 mM after between 10 and 30 min of exercise. Analysis of variance revealed no significant differences between [mean (SD)] CV [14.4 (1.1) km.h(-1)], MLSSV [13.8 (1.1) km.h(-1)] and LTPV [13.7 (0.6) km.h(-1)]. However, the bias +/-95% limits of agreement for comparisons between CV and MLSSV [0.6 (2.2) km.h(-1)], CV and LTPV [0.7 (2.7) km.h(-1)], and MLSSV and LTPV [0.1 (1.8) km.h(-1)] suggest that the extent of disagreement is too great to allow one variable to be estimated accurately from another in individual subjects. Direct determination of MLSSV is necessary if precision is required in experimental studies.

Adult↗
PubMed2004

Correlations between lactate and ventilatory thresholds and the maximal lactate steady state in elite cyclists.

We investigated the validity of different lactate and ventilatory threshold methods, to estimate heart rate and power output corresponding with the maximal lactate steady-state (MLSS) in elite cyclists. Elite cyclists (n = 21; 21 +/- 0.4 y; VO2peak, 5.4 +/- 0.2 l x min (-1)) performed either one (n = 10) or two (n = 11) maximal graded exercise tests, as well as two to three 30-min constant-load tests to determine MLSS, on their personal race bicycle which was mounted on an ergometer. Initial workload for the graded tests was 100 Watt and was increased by either 5 % of body mass (in Watt) with every 30 s (T30 s), or 60 % of body mass (in Watt) with every 6 min (T6min). MLSS was defined as the highest constant workload during which lactate increased no more than 1 mmol x l (-1) from min 10 to 30. In T30 s and T6 min the 4 mmol (TH-La4), the Conconi (TH-Con) and dmax (TH-Dm) lactate threshold were determined. The dmax lactate threshold was defined as the point that yields the maximal distance from the lactate curve to the line formed by the lowest and highest lactate values of the curve. In T30 s also ventilatory (TH-Ve) and Vslope (TH-Vs) thresholds were calculated. Time to exhaustion was 36 +/- 1 min for T30 s versus 39 +/- 1 min for T6 min. None of the threshold measures in T30 s, except TH-Vs (r2 = 0.77 for heart rate) correlated with either MLSS heart rate or power output. During T6 min, power output at TH-Dm was closely correlated with MLSS power (r2=0.72). Low correlations were found between MLSS heart rate and heart rate measured at TH-Dm (r2=0.46) and TH-La4 (r2=0.25), respectively, during T6 min. It is concluded that it is not possible to precisely predict heart rate or power output corresponding with MLSS in elite cyclists, from a single graded exercise test causing exhaustion within 35-40 min. The validity of MLSS predicted from an incremental test must be verified by a 30-min constant-load test.

Adult↗
PubMed2004

Modeling cerebral arteriovenous lactate kinetics after intravenous lactate infusion in the rat.

Venous-arterial lactate differences across the brain during lactate infusion in rats were studied, and the fate of lactate was described with a mathematical model that includes both cerebral and extracerebral kinetics. Ultrafiltration was used to sample continuously and simultaneously arterial and venous blood. Subsequent application of flow injection analysis and biosensors allowed the measurement of glucose and lactate concentrations every minute. Because of the high temporal resolution, arteriovenous lactate kinetics could be modeled in individual experiments. The existence of both a cerebral lactate sink and a lactate exchangeable compartment, representing approximately 24% of brain volume, was thus modeled.

Animals↗